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Egg Nog
04-06-2004, 11:26 PM
This thing is brilliant. Just check the site out, you'll see how it works. It's amazing how much rotational inertia is conserved... just look, you'll see. Revetec is an Australian company, by the way. Genius, mate ;)

EDIT: I just found a few stats on another site... apperently the power stats on this particular unit range from 85hp/250NM to 243hp/300+NM. Keep in mind that this engine weighs 50kg (For comparison, a tiny air-cooled VW flat-4 weighs just over 90kg, and it's a relative featherweight).

This Revetec unit is 50% shorter than a comparable engine. High efficiency, and 12 firing cycles per engine revolution. This design is incredible. I'm completely impressed.

http://www.revetec.com/website/theory/ccedemo5.gif

http://www.revetec.com/website/index.html

Advantages:
approximately one quarter the size and weight of a conventional engine (for similar applications) combined with improved output substantially increases power/weight and torque/weight ratio.

fewer moving and total components. As a result of fewer components, more easily manufactured than conventional engines.

identical cylinder head assembly (“top end”) to conventional engines. Most existing head technology can be either adapted or utilised.

Flexible design - can be four-stroke, two-stroke, petrol, diesel or gas, natural of forced aspiration.

Eliminated irregularly reciprocating components such as connecting rods.

Output shaft can be run in either direction if multilobed cams with symmetrical lobes are employed.

All rotational forces are counteracted via the counter rotating cam – eliminates the need for a heavy flywheel.

Torque and power output can be varied using a fixed capacity and piston stroke.

The CCE can be designed to operate at greatly reduced operating speeds while delivering high torque output.

Substantial reduction in stroke reduces heat loss through cylinder wall.

Extended piston dwell is possible because engine design allows a lower than normal compression ratio to be used reducing power loss from compression cycle.

Maximum mechanical advantage can be applied to output shaft at only 10 degrees ATDC utilising high cylinder pressure early in the stroke, compared to around 60 degrees ATDC for conventional engines.

Lower emissions can be achieved due to increased control over combustion.

Extremely low idle speed due to increase in mechanical efficiency at the top of the stroke.

Little or no bore contact/piston side thrust, which reduces wear on cylinder bore.

Can have different port timing on compression stroke than power stroke allowing better control two-stroke).

Lower centre of gravity.

Due to controlled piston acceleration rates the CCE reduces engine vibration.

A hollow output shaft can be utilised for specialty applications, such as peristaltic pumps.

Coventrysucks
04-07-2004, 01:39 AM
Very interesting. :cool:

Seeing as they are using a Proton Impian as a test vehicle it must be reasonably powerful.

Edit: 85 - 240 hp :cool:
If it has good throttle response and can rev nicely, this would be the perfect engine for a seven replica/ caterham/ westfield etc.

Edit again: Stupidity. :( :D /learns to read properly

fpv_gtho
04-07-2004, 04:29 AM
the Impian's called a Waja here. if you think the names stupid then you'd roll around on the floor over the first advertising campaign Proton had for it.....

nevertheless, the engine looks pretty impressive. im still getting around how it actually works though

sandwich
04-07-2004, 01:13 PM
so when do I get my flat 12 pushing 600 HP on pump gas? That can be daily driven? That weighs as much as a v6?

hmmm? hmmmmmm? :cool:

Need4Speed
04-07-2004, 06:33 PM
Not bad!

Considering the weight of it(50kg) it the power to weight ratio :D would be real good. and furthur developments, if it is succesfull could mean a new engine of the roads.
Gotta learn more about it, its interesting!!!

1000bhp1000nm
04-09-2004, 10:24 AM
wow...all i can say is...why din they think of this earlier? man, this could revolutionise engine design...it'll change everything...as eggnog said, this is the result of a pure genius...i'm just dumbfounded...i was learning so much about our conventional IC engine lately...and now i might have to throw it all out the window!!! they might win the nobel price with this!!!can't wait for a force induction version of a 4 cylinder version, man, it can as well pump 400hp!!!

and i have to say, they are dumb to experiment the worlds most ingenius engine on the worlds crappiest car...you think the name is stupid? wait till you test drive it...why can't they test it any other cars?

UK CARS
04-09-2004, 10:48 AM
yeah great idea :) do you think this will ever catch on? :confused:

sandwich
04-09-2004, 11:58 AM
I don't, and here's why:

the costs of gearing up for production of such an engine would be immense when compared to current products. Think of how many cars use the same engine....So you'll need a full on assembly line from the ground up. Not only that, but the engine does not YET offer a significant improvement in the efficiency department, and this is where ALL manufacturers are going to be looking in the new future. Engines are powerful enough, but they need to get more mileage out of them. An experimental engine will likely not be the answer for most companies.

However, the engine does offer a GREAT advancement in the performance department. There's a good possibility of a manufacturer picking it up as a sports car engine (a la mazda's rotary) or a racing team using it or a similar design. The problem will be the designers themselves....will they kill their own child looking to get rich? They will hold the liscensing, and anybody who wants to use it will have to pay royalties.....why pay royalties when you've got something that works, and works NOW? I doubt these guys have the capability to produce in mass quantities (may be wrong) so they will need somebody who can.

My guess? It ain't gonna happen. You'll probably see a few Radicals or other trackday cars with them as an experiment, but I doubt the project will ever leave the ground.

I really hope I'm wrong.

Ferrari Tifosi
04-10-2004, 06:44 PM
I don't, and here's why:

the costs of gearing up for production of such an engine would be immense when compared to current products. Think of how many cars use the same engine....So you'll need a full on assembly line from the ground up. Not only that, but the engine does not YET offer a significant improvement in the efficiency department, and this is where ALL manufacturers are going to be looking in the new future. Engines are powerful enough, but they need to get more mileage out of them. An experimental engine will likely not be the answer for most companies.

However, the engine does offer a GREAT advancement in the performance department. There's a good possibility of a manufacturer picking it up as a sports car engine (a la mazda's rotary) or a racing team using it or a similar design. The problem will be the designers themselves....will they kill their own child looking to get rich? They will hold the liscensing, and anybody who wants to use it will have to pay royalties.....why pay royalties when you've got something that works, and works NOW? I doubt these guys have the capability to produce in mass quantities (may be wrong) so they will need somebody who can.

My guess? It ain't gonna happen. You'll probably see a few Radicals or other trackday cars with them as an experiment, but I doubt the project will ever leave the ground.

I really hope I'm wrong.

I agree with you. There have been countless different engine designs and they never make it because of the reasons you just stated. However, this is a very innovative and interesting design. Never seen anything like this. It would be cool to see one of these engines in a race car at some point.

Need4Speed
04-11-2004, 03:02 AM
True the chances of the 'Revteck' engine making it into the market seem slim, but if a company is looking for something different, and wants the edge it might focus its engineers on such an engine. Performance car companies, such as ferrari. An all production line car company that could try something new like this could be Mercedes, they are doing great as it is and something new like this could boost publicity and sales. ;)

Sia
05-02-2004, 09:06 PM
It really is quite amazing what this technology can do. I bought shares in this company over five years ago when it was still in its early stages. I saw the potential of teh engine then, and it is now beginning to bare fruit. It is good to see that they are dealing with Proton, and the Triton plus a swarm of other interesting new business developments.

If anyone is interested in buying some shares off me, send me an email at [email protected]. I am willing to offload the shares at a discounted price becuase I have so many of them.

crisis
05-03-2004, 12:07 AM
While the move to alternative and hybrid motive power seems to be gaining momentum, it will be difficult for new types of pure internal combustion engines to gain headway. If the design is as lightweight and efficient as it seems, it may be a good idea for the inventor/developer to work with these hybrid concepts.

crisis
05-03-2004, 12:09 AM
Seems the Aussies are coming up with a few good ideas. I read in the weekend paper about a South Aussie who has a new concept for electric motors which is way more efficient. Ill see if I can find more info.

whiteballz
05-03-2004, 12:24 AM
there is an aussie company that is doing something for a trucks engine, its hydrolic somethings change directions so the the oil used for breaking is stored pressurised and when the driver accelerates that oil is re-used to accelerate faster. it saves something like 60 feet of the bearking times 100 kph-0 and 27 or so % of fuel ecconomy. i cant remember if thats correct, but its very impressive.

eyebrows
05-03-2004, 03:09 AM
yeh i heard about this but i was on holidays so i didn't listen, that was a while back wasn't it?

Falcon500
05-03-2004, 04:20 AM
There have been alot of companys come up with good ideas...only to be bought out by largemanufactuors so they stop developing their own technologys...that and lack of intrest...

Matra et Alpine
05-03-2004, 04:47 AM
There have been alot of companys come up with good ideas...only to be bought out by largemanufactuors so they stop developing their own technologys...that and lack of intrest...
to be fair to the big-guys, often it's because they've already done it.

Re-generative braking has been used in different guises in British busses for decades. The most common one is pretty much what was described, the wheels push hydralic pressure into a reservoir when braking and release it back out when taking away. ( What might be clever with this suggestion given is if it were built into the ENGINE ) Electric's been done too. But, the scariest one was in the 50s (IIRC) when they stored it in a flywheel ! I just had visions of this few hundred pound wheel spinning at 20Ks breaking free and mutilating everyone in the bus - I was a kid at the time :)

Egg Nog
05-03-2004, 08:58 PM
Electric's been done too. But, the scariest one was in the 50s (IIRC) when they stored it in a flywheel ! I just had visions of this few hundred pound wheel spinning at 20Ks breaking free and mutilating everyone in the bus - I was a kid at the time :)

Ahhh the memories, eh? ;)

There's dozens of electric buses in Vancouver... connected to overhead lines that run over certain roads just for the purpose. It's pretty amazing... I've never heard of any problems associated with them, either.

In West Vancouver, where I live, they're also running one hybrid diesel/electric bus. It's fairly nice, and the space taken up by the electrics is fairly minimal. Only 2-4 seats at most.

link1
06-09-2004, 04:51 AM
Revetec Limited is currently selling shares for $1.30 Australian each. If you would be interested in purchasing some cheaper, contact [email protected]. Larger discounts will be offered for larger quantities. Shares may also be swapped for real estate or other items of interest.

Matra et Alpine
06-09-2004, 05:18 AM
Revetec Limited is currently selling shares for $1.30 Australian each. If you would be interested in purchasing some cheaper, contact [email protected]. Larger discounts will be offered for larger quantities. Shares may also be swapped for real estate or other items of interest.
Please explain YOUR role in this share offer.
We don't like SPAM here on UCP :)

link1
06-21-2004, 03:43 AM
I am a Revetec shareholder and am looking at selling some of my shareholding. If you would like to be a part of this new technology, but don't want to pay $1.30 each I am willing to sell my shares at a discount. Reply to [email protected].

Gnafu the Great
06-22-2004, 12:29 PM
Ooh, totally awesome ^^. I'd love to pop one of these into an Ultima GTR, hehe.

EDIT: I'm referring to the CCE engine, not to any of the discussion following the initial post.

ace
06-25-2004, 05:39 PM
I am a Revetec shareholder and am looking at selling some of my shareholding. If you would like to be a part of this new technology, but don't want to pay $1.30 each I am willing to sell my shares at a discount. Reply to [email protected].
Revetec does not seam to be listed on the ASX (Australian stock exchange) there for I must assume that they are selling the shares in there company privately.
My advice to anyone interested in this company enough to invest money should deal directly with the company.
Buying shares privately from unknown individuals is fraught with danger especially internationally.

GTR Dreamer
06-25-2004, 05:56 PM
It really is quite amazing what this technology can do. I bought shares in this company over five years ago when it was still in its early stages. I saw the potential of teh engine then, and it is now beginning to bare fruit. It is good to see that they are dealing with Proton, and the Triton plus a swarm of other interesting new business developments.

If anyone is interested in buying some shares off me, send me an email at [email protected]. I am willing to offload the shares at a discounted price becuase I have so many of them.

you spamer!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
i tried sending an email to you and it said there is no such address!!!!!!!!!!
:eek: :eek: :eek: :mad: :mad: :mad: :mad: :mad:

CHOOK
07-22-2004, 06:20 PM
Revetec does not seam to be listed on the ASX (Australian stock exchange) there for I must assume that they are selling the shares in there company privately.
My advice to anyone interested in this company enough to invest money should deal directly with the company.
Buying shares privately from unknown individuals is fraught with danger especially internationally.

Very true ACE.

For those who have doubts about the future of this engine, please visit the website (www.revetec.com) and view their Latest News where you will find a link to a Message From the Directors To Shareholders.

If you were thinking of buying shares before a public listing then you should be very quick. As an existing shareholder, I recommend that you contact the company to buy any shares.

The future looks bright.
:cool:

crisis
07-23-2004, 12:20 AM
Very true ACE.

For those who have doubts about the future of this engine, please visit the website (www.revetec.com) and view their Latest News where you will find a link to a Message From the Directors To Shareholders.

If you were thinking of buying shares before a public listing then you should be very quick. As an existing shareholder, I recommend that you contact the company to buy any shares.

The future looks bright.
:cool:
A possible ramp?

CHOOK
08-04-2004, 12:35 AM
They released preliminary figures today as well as how/when they plan to list on the Stock Exchange, a hybrid project and other companies they are in negotiations with.

The figures are very impressive but they are still working on further improvements.

Click on Latest News on their website.

www.revetec.com

stian1979
02-23-2006, 01:12 AM
THIS MESSAGE WAS MOVED FROM THE F1 EFFICIENCY THREAD AS IT WAS GETTING OUT OF HAND AND FOCUSSING ON THE Revetec . MetA .....


That's POWERTEC :) http://www.radicalextremesportscars.com/news_folder/v8stepsup/indexspec.php it's really just an ultra light V8, nothing too special :D

Revetec is the neat new Aussie designed engine ....
http://www.revetec.com/files/_images/DSC_0195.preview.jpg

http://www.revetec.com/?q=videos

Revtec? did you even read what they say about the engine? it fire 3times per revelution and then it will also produce 3 times more torque, but also consume 3times more fuel.
Well to be totaly corect it produce 2.9 times more torque so it actualy 3,33%les fuel efficiant than a engine at same power because of reduced torque per workcycle because of increased piston speed decrease the filling of the air fuel mixure.
The bearings on the side of the piston how long will they last?
I belive the heavy crankshaft mecanism will make the engine heavy.
It has to be a bokser design with all the disandvantages that have. a boker is more heavy than a inline or v engine at simular size.
cylinders will quicker ger oval.

Here is another crazy dude www.new4stroke.com

Matra et Alpine
02-23-2006, 04:08 AM
Revtec? did you even read what they say about the engine? it fire 3times per revelution and then it will also produce 3 times more torque, but also consume 3times more fuel.
That relationship depends on efficiency and lossses which you've clearly ignored :)
No engine is going to be radically different in perfromance, but a few aroudn just now are promising incremental improvements.
But the Revetec is reported LOWER consumption. So can you give where you're getting your info from ?

The bearings on the side of the piston how long will they last?
I think you are confusing Wankel seals with Revetec bearings.
IT's a bearing, just the same as there is a journal ( ie bearing surface ) on a crankshaft and a gudgeon pin !! The design permits that to be a roller bearing which will have a MUCH longer life than shells :D

I believe the heavy crankshaft mecanism will make the engine heavy.
no conrods :) How do you equate heavy weight ?

It has to be a bokser design with all the disandvantages that have. a boker is more heavy than a inline or v engine at simular size.
cylinders will quicker ger oval.
now you're just makign stuff up :D
Good for a laugh tho'
So WHY is it going to oval the cylinders given that there are no sideways forces as with a conrod design ????
Boxers dont' HAVE to be heavier -- where are you reaching that conclusion ?

Here is another crazy dude www.new4stroke.com (http://www.new4stroke.com)
Never really a starter as too many moving components facign compression sealing issues.
Vovlo variable compression engine is the best implementation of all the attmpets to deliver it over the decades.

If you have access to more techncial details on the Revetec I'd love you to share them as it can be difficult reading past the marketing hype :D

stian1979
02-23-2006, 06:53 PM
That relationship depends on efficiency and lossses which you've clearly ignored :)
No engine is going to be radically different in perfromance, but a few aroudn just now are promising incremental improvements.
But the Revetec is reported LOWER consumption. So can you give where you're getting your info from ?

I think you are confusing Wankel seals with Revetec bearings.
IT's a bearing, just the same as there is a journal ( ie bearing surface ) on a crankshaft and a gudgeon pin !! The design permits that to be a roller bearing which will have a MUCH longer life than shells :D

no conrods :) How do you equate heavy weight ?

now you're just makign stuff up :D
Good for a laugh tho'
So WHY is it going to oval the cylinders given that there are no sideways forces as with a conrod design ????
Boxers dont' HAVE to be heavier -- where are you reaching that conclusion ?

Never really a starter as too many moving components facign compression sealing issues.
Vovlo variable compression engine is the best implementation of all the attmpets to deliver it over the decades.

If you have access to more techncial details on the Revetec I'd love you to share them as it can be difficult reading past the marketing hype :D

http://www.revetec.com/?q=taxonomy/term/20

read this and you see what I mean. They say they good more torque but it's a lie since it produce actualy less torque per work cycle. The fuel should be the same since it's using engine comparison at same deplasement and same cylinder preshure. It show bether fuel efficensy at low rpm but this is due to bether flow in the valves since the engine has higher piston speed at same rpm than a convensional engine. so a convensional engine would have the same fuel efficensy at the same torque. Tehy only read out the data that make the engine look good.

The bearings I'm refering to is the ones transfering the power from the pistons to the big dishes I would call a crankshaft.

Those shafts with those big cams and the mecanism to handle the contrarotating operation must be more heav than anny conrods.

Boxers get oval more easy because the gravety pull the pistons down against he ground. Why is it only two brands in the worls using boxers? It has good balance and low center of gravety so why is it not more that use them?
a inline will be lighter because it require less material since making only one bank conectet to the crankcase. A smal V will make the Banks share some material and big V vill make the engine more heavy because the banks no longer share anny material so it has to be conectd to the crankcase bye it's own. A boxer is practical a 180 degre V engine.

Renult had a 110decre f1 engine but give it up because it become to heavy.
They went back to a more moderate angle.
http://i43.photobucket.com/albums/e353/stian1979/V-enginevsboxer.jpg
Know what I mean?

Matra et Alpine
02-24-2006, 01:56 AM
http://www.revetec.com/?q=taxonomy/term/20

read this and you see what I mean. They say they good more torque but it's a lie since it produce actually less torque per work cycle. The fuel should be the same since it's using engine comparison at same displacement and same cylinder pressure. It show better fuel efficiency at low rpm but this is due to bether flow in the valves since the engine has higher piston speed at same rpm than a convensional engine. so a convensional engine would have the same fuel efficensy at the same torque. Tehy only read out the data that make the engine look good.
Smaller lighter faster engines are generally MORE efficient as their are less losses. You conjecture has validity if the Revetec ends up with the linear mass movement of the "normal" engines, but it replaces some of that and most importantly increases the energy extracted from the piston movement by operating with no side force vectors from cranks. IF they can run the engine at optimum revs for efficiency BECAUSE it produces higher torque then it wins. That is their stated position and THEY DO claim BETTER fuel efficiency. I've not seen anything that backs up to the contrary. As I said I think you speculation uses "normal" limits and tries to apply them to REvetec. I dont agree they're comparable.

The bearings I'm refering to is the ones transfering the power from the pistons to the big dishes I would call a crankshaft.
yep, and HOW is that different to a gudgeon pin in a "normal" engine ?
I'd also forgotten that they have alignment shafts that retain piston alignment so would suggest removal of "slap" allowing a much smaller skirt and possibly lower mass piston.

Those shafts with those big cams and the mecanism to handle the contrarotating operation must be more heav than anny conrods.
How do you reach that conclusion ?
They are NOT subject to the needs of thinness of a conrod to be able move the piston. So they dont' need to be as substantially built. They are much shorter in throw too. The engine wins because it does NOT use a crankshaft -- which has counter weighted lobes -- and is more efficient in power extraction per combustion because there is no angular vector from a conrod.

Boxers get oval more easy because the gravety pull the pistons down against he ground.
??? Who told you that ?
The effect of gravity is MINISCULE relative to the combustion forces in the engine :)

Why is it only two brands in the worls using boxers? It has good balance and low center of gravety so why is it not more that use them?
PACKAGING. You get a WIDE engine hard to fit in.
Boxers are WIDELY used in light planes because then the packaging can actually be an advantage !! You dont' get many places where reliability and performance are any more important than a light aircraft :D
Boxers are a BIG win when you go air=cooled. But by the time you add a water jacket then a 4 isn't as efficient packaging as a straight.

a inline will be lighter because it require less material since making only one bank conectet to the crankcase. A smal V will make the Banks share some material and big V vill make the engine more heavy because the banks no longer share anny material so it has to be conectd to the crankcase bye it's own. A boxer is practical a 180 degre V engine.
Boxer and V180 are different as boxer is opposed piston and naturally balanced in all configurations whereas a V180 isn't. But the packaging is similar. There is a small difference in weight in the block but it' s arguable that the bottem end is stronger in a boxer wieight-for-weight as you dont' need to build extra ribs to stop the crank twisting out the bottom of a "normal" block.

Renult had a 110decre f1 engine but give it up because it become to heavy.
They went back to a more moderate angle.
NO, they coudln't control the VIBRATIONS that the unusual angle introduced.

Know what I mean?
Some of what you say is valid but there is a counter argument for each of them that the Revetec design seems to have used. I have commented where I think you take the poor points that a crank based engine has and then assumed it applies to the Revetec esp with regard to the cylinders. With NO sideways forces during the cycle then theoretically the block requires less stiffening, less thickness less weight !!
THE big benefit the Revetec design goes for is the removal of the angular forces a crankshaft imparts. SO removing all the necessary design to cope with those stresses and wear.

stian1979
02-24-2006, 07:03 AM
Smaller lighter faster engines are generally MORE efficient as their are less losses. You conjecture has validity if the Revetec ends up with the linear mass movement of the "normal" engines, but it replaces some of that and most importantly increases the energy extracted from the piston movement by operating with no side force vectors from cranks. IF they can run the engine at optimum revs for efficiency BECAUSE it produces higher torque then it wins. That is their stated position and THEY DO claim BETTER fuel efficiency. I've not seen anything that backs up to the contrary. As I said I think you speculation uses "normal" limits and tries to apply them to REvetec. I dont agree they're comparable.

yep, and HOW is that different to a gudgeon pin in a "normal" engine ?
I'd also forgotten that they have alignment shafts that retain piston alignment so would suggest removal of "slap" allowing a much smaller skirt and possibly lower mass piston.

How do you reach that conclusion ?
They are NOT subject to the needs of thinness of a conrod to be able move the piston. So they dont' need to be as substantially built. They are much shorter in throw too. The engine wins because it does NOT use a crankshaft -- which has counter weighted lobes -- and is more efficient in power extraction per combustion because there is no angular vector from a conrod.

??? Who told you that ?
The effect of gravity is MINISCULE relative to the combustion forces in the engine :)

PACKAGING. You get a WIDE engine hard to fit in.
Boxers are WIDELY used in light planes because then the packaging can actually be an advantage !! You dont' get many places where reliability and performance are any more important than a light aircraft :D
Boxers are a BIG win when you go air=cooled. But by the time you add a water jacket then a 4 isn't as efficient packaging as a straight.

Boxer and V180 are different as boxer is opposed piston and naturally balanced in all configurations whereas a V180 isn't. But the packaging is similar. There is a small difference in weight in the block but it' s arguable that the bottem end is stronger in a boxer wieight-for-weight as you dont' need to build extra ribs to stop the crank twisting out the bottom of a "normal" block.

NO, they coudln't control the VIBRATIONS that the unusual angle introduced.

Some of what you say is valid but there is a counter argument for each of them that the Revetec design seems to have used. I have commented where I think you take the poor points that a crank based engine has and then assumed it applies to the Revetec esp with regard to the cylinders. With NO sideways forces during the cycle then theoretically the block requires less stiffening, less thickness less weight !!
THE big benefit the Revetec design goes for is the removal of the angular forces a crankshaft imparts. SO removing all the necessary design to cope with those stresses and wear.

If I got a normal crankshaft and get 100Nm at 1000rpm and a normal crankshaft that get 290Nm at 3000rpm would you then say it's a bether engine? You cant compare two engines with same stroke at diferent piston speed. If the revetec has only 1/3 of the revelution it stil have the same piston speed. At low speed it will show a bether fuel comsumption because it has a piston speed that alow it to fill the cylinder more efficiant, but average it will have the same fuel comsumtion as a normal engine.

The bearings on a normal piston and rod conection the movement is only 2cm per revelution since it only go back and forvard. The revetec has to roll all the way along the crankshaft rotation witch mean it has to travle 1/3 of the distance of the shaft per work cycle.

That delta shaped shaft has to be heavy! and don't tell me they wont nead a extra gear mecanism to runn those contra rotating.

Alfa tryed a 12cyl boxer in F1 and it did not win anny championship (it did not prove reabile)

I read about revetec a couple of week's ago and the more I think the less I like it. If I use a normal engine and runn it at 3 times the revelution and use a 3:1 gearbox I will have the same results as this guys did - I don't nead to waste time on all that engineering.

It's a funn project, but so was my steam engine

Matra et Alpine
02-24-2006, 10:26 AM
If I got a normal crankshaft and get 100Nm at 1000rpm and a normal crankshaft that get 290Nm at 3000rpm would you then say it's a bether engine?
Depends where the other one delivers 290Nm ?
By only takign one variable it creates a false impression.
I'm not sure what you are trying to say.

You cant compare two engines with same stroke at diferent piston speed. If the revetec has only 1/3 of the revelution it stil have the same piston speed.
NO IIRC they run smaller displacement and use the swept volume to do comparisons.

At low speed it will show a bether fuel comsumption because it has a piston speed that alow it to fill the cylinder more efficiant, but average it will have the same fuel comsumtion as a normal engine.
Where do you ahve the evidence for that ?

The bearings on a normal piston and rod conection the movement is only 2cm per revelution since it only go back and forvard. The revetec has to roll all the way along the crankshaft rotation witch mean it has to travle 1/3 of the distance of the shaft per work cycle.
Their is rotation in the gudgeon pin and FULL rotation on the crankshaft AND the main journal.
Mating surfaces and materials are what makes for bearing resistance and wear.
Again, it's not clear what you are trying to say.

That delta shaped shaft has to be heavy! and don't tell me they wont nead a extra gear mecanism to runn those contra rotating.
Why is it heavy ? There is no rationale for reaching that conclusion. You dont' knwo the materials or the tesile strenght requriements. The "extra" gear is there and as reported in many artciels the "bottom end" fo the Revetec is signifiacnlty lighter than it's coutnerparts. If you really need me to confirm that I'm sure I can find the original press releases -- in fact it's propbably up here on UCP :)

Alfa tryed a 12cyl boxer in F1 and it did not win anny championship (it did not prove reabile)
So Alfa ( actually blame Subaru :) it never really had any chance to be developed to prove itself ) didn't make it work and so all flat 12s are bad ? hmm Ferrari WON CHAMPIONSHIPS with a flat 12 and the greatest sportscar of all time the Posrsche 917 used a flat 12

I read about revetec a couple of week's ago and the more I think the less I like it. If I use a normal engine and runn it at 3 times the revelution and use a 3:1 gearbox I will have the same results as this guys did - I don't nead to waste time on all that engineering.
yeah right.
THe BIGGEST issue in engines is the piston crontrol and the crankshaft componetnry. The Revetec is one of many that are utilising modern methods and materials to provide different linkages not possible in the past. They've published numbers better than alternatives and have a deal with Honda to build in China.

It's a funn project, but so was my steam engine
Whether it ends up a niche or mainstream it has some clear benefits ( which you've ignored/misunderstood )
AS said earlier, nobody is going to bring out an engine twice as powerful or efficient as any other competitor. Engine design isn't about that anymore that all happened 80 years ago :D But this does have definable engineering improvements and it woudl be nice to see it flourish and give options.

stian1979
02-24-2006, 08:26 PM
Depends where the other one delivers 290Nm ?
By only takign one variable it creates a false impression.
I'm not sure what you are trying to say.

NO IIRC they run smaller displacement and use the swept volume to do comparisons.

Where do you ahve the evidence for that ?

Their is rotation in the gudgeon pin and FULL rotation on the crankshaft AND the main journal.
Mating surfaces and materials are what makes for bearing resistance and wear.
Again, it's not clear what you are trying to say.

Why is it heavy ? There is no rationale for reaching that conclusion. You dont' knwo the materials or the tesile strenght requriements. The "extra" gear is there and as reported in many artciels the "bottom end" fo the Revetec is signifiacnlty lighter than it's coutnerparts. If you really need me to confirm that I'm sure I can find the original press releases -- in fact it's propbably up here on UCP :)

So Alfa ( actually blame Subaru :) it never really had any chance to be developed to prove itself ) didn't make it work and so all flat 12s are bad ? hmm Ferrari WON CHAMPIONSHIPS with a flat 12 and the greatest sportscar of all time the Posrsche 917 used a flat 12

yeah right.
THe BIGGEST issue in engines is the piston crontrol and the crankshaft componetnry. The Revetec is one of many that are utilising modern methods and materials to provide different linkages not possible in the past. They've published numbers better than alternatives and have a deal with Honda to build in China.

Whether it ends up a niche or mainstream it has some clear benefits ( which you've ignored/misunderstood )
AS said earlier, nobody is going to bring out an engine twice as powerful or efficient as any other competitor. Engine design isn't about that anymore that all happened 80 years ago :D But this does have definable engineering improvements and it woudl be nice to see it flourish and give options.

This revetec has same displasement as a normal engine. so at 1000RPM it's going to do the same work as a convensional engine at 3000RPM
But the average Nm output is only 2,9 of what a normal engine can do at the same RPM. Why? ask yourself this.

Evidence I find trough experience and reading betwen the lines.

how long is the distance around the camprofile on revetec's crank? the bearing on the pistion has to go this distance in case you did not notice.

Tradisjonal bearings only nead to travle a short distance and then back in the connection at the pistion and the distance round the crank that is short compared to the revetec.

This statement say it all.

The power output is similar to a conventional engine, but given that the significant improvement in torque output is almost three times that of a conventional engine kW=Nm x RPM
Sorry but it's not posible.



I can at least tell you that it's more heavy than a normal crankshaft can be made.

Ferrari, meclaren and others make supercars with v engine. Why not the boxer? The disanvantage of space is gone when you have mid engine cars.
They get a lower center of gravety so why not use it? You can only refear to 1 race car doing good on the track with a boxer?

Why was this linkage not posible in the past?
So just because it's build in China it's good? Newer heard that one befour.

Otto and Diesel was engineer's so they knew what they where doing and they did it well.

stian1979
02-24-2006, 08:53 PM
I found this on a other forum I'm a member of 3 week's ago that I think it's a good statement. It's from the FIA forum.


Revetec is another example of a crap engine idea turned expensive development project. More victims of the torque uber alles mentality, and again fleecing large numbers of uniformed investors because of it.

They have a boxer engine with all the weight and bulk penalties associated with doubling up on cams, blocks, heads, manifolds etc. (There is a reason why boxers are not the standard engine format). To this they add a cam drive system for the pistons, with huge bearing issues. In essence all they are doing is replacing the crankshaft with a much trickier dual counterrotating three lobed camshaft.

So now they are crowing about getting three times the torque. Like that is some kind of miracle when you have three times as many piston strokes per crankshaft revolution! And they have only managed to get 150Nm out of a 1.4l engine (equivalent to about 35Nm per litre from a conventional engine or one third that of a good racecar engine (110Nm/litre) at a maximum speed of 2600 rpm (because of course the pistons are going at 7800 rpm at that speed).

But of course they haven't told the world that that is the limit in terms of their rpm. Or that a good inline four will produce three times the power they have achieved, or that high torque/low rpm is bad in that it means a much heavier and more expensive clutch and gearbox. Or that the piston driving bearings are spinning at huge speeds and are likely to pound themselves and the cam to pieces in short order.

There should be a website created to debunk idiot ideas like these. Or maybe I should loosen my morals and become the one parting the stupid people from their money.

End of rant

I think it neads bether explenation than this.

Matra et Alpine
02-25-2006, 06:47 AM
This revetec has same displasement as a normal engine. so at 1000RPM it's going to do the same work as a convensional engine at 3000RPM
That ignores the problem that the angular conrod has in losses in a"normal engine". The Revetec is one of a number of "new" ideas being explored just now that address that significant loss. It's THAT that makes oval cylinders BTW :D

But the average Nm output is only 2,9 of what a normal engine can do at the same RPM. Why? ask yourself this....Evidence I find trough experience and reading betwen the lines.
That's the issue "evidence" is from everyone reading between lines and applying "normal" engine layout issues to IT.

how long is the distance around the camprofile on revetec's crank? the bearing on the pistion has to go this distance in case you did not notice.
Wrong. The important point about a bearing is it's "contact" surface area. The actual points that has force applied to it. THAT has to either be on rollers or on pressurised lubricant. The issue the Revetec has is that you cant' build up an oil surface the way a rotating journal does. Bu we have new materials :D It's "pseduo science" like that that raises the question marks over the comments :D

Traditional bearings only nead to travle a short distance and then back in the connection at the pistion and the distance round the crank that is short compared to the revetec.
IRRELEVANT.
You need to learn a bit more about bearings :( See comment above.

This statement say it all.
kW=Nm x RPM
Sorry but it's not posible.
aha, the "ideal" engine>?
And why do engines NOT achieve the "perfect" numbers ?
Why are some engines more "efficient" and get closer than others ?
Yep. Think it out. As I have said the thing the Revetec is trying to deliver is the recovery of the loss in power from the operation of a crank. A significant loss and wear factor in an engine.

I can at least tell you that it's more heavy than a normal crankshaft can be made.
Seriously, You WEIGHED a crank ?
Look at the lobes opposite to the pistons for balance !!
It clearly have to find you the quote rather than taking my word that I'd read an early press release saying the bottom end was lighter :( Did you search the previous UCP posts ??

Ferrari, meclaren and others make supercars with v engine. Why not the boxer? The disanvantage of space is gone when you have mid engine cars.
Well done --- PACKAGING :D
NOT the engine per-se --- as I said.

They get a lower center of gravety so why not use it? You can only refear to 1 race car doing good on the track with a boxer?
Reading ? ....... PACKAGING ... the boxer engine prevents a race car from using ground effects and body venturis because it's in the way. It works reasonably well in a WRC rally car but does give problems in locating other things -- and hence the Subarus propensity for tearing intercoolers off being limited on placement :(

Why was this linkage not posible in the past?
Materials. Computing power to innovators to do EAD and stress analysis.
( See the Polish moving piston valves engine that the guy built in his garage L) )
There are many innovators out there trying the new ideas that in theory address limitation of our current designs.
It goes on all the time. The difference is that thanks to the internet we can see, explore and critique these solutions in a way not possible in the past.

So just because it's build in China it's good? Newer heard that one befour.
Now THAT is just a stupid response, isn't it.
HONDA is the company reputedly in the deal.
Tells a lot on your thinking process that you ignored that it might be a MAJOR PLAYER and instead tried to make it sound negative because it was China :D
All it did was remove respect for your comments.

Otto and Diesel was engineer's so they knew what they where doing and they did it well.
And modern engineers ARENT for what reason ?
And what about all those hundreds of engineers who were developing engines at the same time ? How much do you know about engine development and history ? Watt, Moorland, Brown, Matteucci, Stirling, the list is HUGE.

Matra et Alpine
02-25-2006, 07:02 AM
I found this on a other forum I'm a member of 3 week's ago that I think it's a good statement. It's from the FIA forum.



I think it neads bether explenation than this.
Sorry but "doubling up on cams" is one of theose STUPID responses I read so many times from folks who have never built anything :D

Lets take an engine that needs 2 valves per cylinder so we need 8 cam lobes on a 4potter.

If you used a pushrod then it's a no brainer, no difference :D If hte engine doesn't rev hard that's a distinc possibility :D

If we assume worst cases -- ie over head cam then you need a drive pulley - which is VERY light and then the 4 lobes and the 4 connecting shaft sections in each head. SO the only difference is the pulley and once shaft connecting section. NOT A LOT :D

If you go twin cam to get optimum valve angles then it's 2 extra pulleys and 2 extra connecting shaft piece ( ie abtou 1" long, 1/2" diameter. )

SO sorry, it's RUBBISH to harp on about all this "extra weight" :D

As someone who has spent too many hours in garages and workshops trying to minimise weight in race/rally engines it's a NONSENSE to make multipel cams out to be a disadvatage. the decision to go multile VALVES carries the penalty not signifactnly where you put them :D

THe writer also confuses efficiency and power.
IF you can make an engine 5% more efficient then revs etc are irrelvant as you then use gearing to make that engien operate in that optimum area. It's. I suspect, why they went for pumps initially as they are run at their optimum efficiency for long times, same with aircraft engines. Cars with proper CVTs are the same.

stian1979
02-25-2006, 10:17 AM
Are you the designer of this pice of crap?
You try to defend something that annyone can see is a hopeless idea.
Do you know how mutch is lost in a engine because of friction?
It's nothing compared to what you loss in heat radiation, coolong water and heat trough exhaust. It's a none exsisting problem.
If someone want's seriosly to make some diferense they would put there intention to experiments with materials that don't nead cooling and ways of heat rescovering.
Same HP and 3 times the torque is inposible.
kW=Nm x RPM
This is the same for sterling, steam, diesel, otto, wankel, 1 shaft gasturbine, 2 shaft gasturbine, 3 shaft gas turbine and ac/dc motors. This formula is the same for anny engine design. kW=kNm/s=kJ/s You can argue this all you want, but it's a fact that will not go away. Go to a tecnical high school and ask about the realationship betwen RPM,kW and Nm, but you will probartly say the guys there have no clue what they are talking about.
You don't acept the conserns I have about boxers, but you make up your own as a exhuse for it not to be the leading design(do you think revetec is going to remove those conserns you came up with yourself?)
The gas turbine is advanced and the first one was buildt in 1906. The Napier deltic was advanced and build in the 40's. What is so special with the revetec that made it inpoible until now when computers show up?
Otto and Rudolf was good enginers and so was sterling. He's engine is one of the moust efficiant, but it are to slow to speed up so sadly enough it can't be used for mutch.

Matra et Alpine
02-25-2006, 10:30 AM
Are you the designer of this pice of crap?
No, but I'm a realistic engineer who can see what they are trying to make better.
And a designer who can recognise others ideals and efforts.

You try to defend something that annyone can see is a hopeless idea.
No I try to defend someones idea from people who havent' thought it through and seem to know little about the engineering :)

Do you know how mutch is lost in a engine because of friction?
yes. do you ?

It's nothing compared to what you loss in heat radiation, coolong water and heat trough exhaust. It's a none exsisting problem.
oops, clearly NOT :D

If someone want's seriosly to make some diferense they would put there intention to experiments with materials that don't nead cooling and ways of heat rescovering.
Correct and there are other engineers out there doing that too.
Is an improvement only to be considered if it makes EVERYTHING better ?
:D
As I have pointed out what they are mainly concerning themselves with are the losses that offset crank in a normal engine causes. It's IS significant and when you tune an engine up becomes THE most common cause of engine failure :D

Same HP and 3 times the torque is inposible.
It all depends where the HP is measured. Peak or at the same point on the torque curve.

kW=Nm x RPM
This is the same for sterling, steam, diesel, otto, wankel, 1 shaft gasturbine, 2 shaft gasturbine, 3 shaft gas turbine and ac/dc motors. This formula is the same for anny engine design. kW=kNm/s=kJ/s You can argue this all you want, but it's a fact that will not go away. Go to a tecnical high school and ask about the realationship betwen RPM,kW and Nm, but you will probartly say the guys there have no clue what they are talking about.
wow, I and WHAT happened to LOSSES in your ideal model of the world ?
THAT is what was pointed out to you> You've got 1/10th of the information about an engine and implying far too much from it :(

You don't acept the conserns I have about boxers, but you make up your own as a exhuse for it not to be the leading design
Sorry, I have responded to every one of your concerns with Boxer and refuted some of them> Liek the F1 nonsense and the "they all fail" rubbish. Don't confuse that with not also recognising their REAL problems ( and it's NOT oval cylinders because of gravity : ! ROFL :) )

(do you think revetec is going to remove those conserns you came up with yourself?)[/quote}
I doubt Revetec will remove the problems a boxer inherently has.
BUT that doens't mean they can't make a more efficient "boxer" and where boxer engines HAVE proven themselves that they may be better !!
Do I think as Revetec could ever be a racing engine ? No I doubt it, but that's not what they're setting out to do :D
[quote]The gas turbine is advanced and the first one was buildt in 1906. The Napier deltic was advanced and build in the 40's. What is so special with the revetec that made it inpoible until now when computers show up?
The abacus was the first hand held computer and designed thousands of years ago ... does that mean laptops and PDAs arne't "special" ? You're argument is non-sensical.
"advanced" for their day is the key terms. You'er getting all mixed up now :(

Otto and Rudolf was good enginers and so was sterling. He's engine is one of the moust efficiant, but it are to slow to speed up so sadly enough it can't be used for mutch.
So what ? ( btw it's StIrling - A fellow Scot :) )
At least you NOW recognise that there are many designers and who knows in 10 years someone may hold the Revetec up as an important evolution and maybe they'll say that it can't be used for much> Does that remove from the engine objectives ? No. But you seem to be working hard selecting information shared to try to avoid that the Revetec is offering something different and MAY be better and has at least got ONE MAJOR company interested enough to think about production. ( That's more than Da Vinci managed with HIS engine :) )

Matra et Alpine
02-25-2006, 10:43 AM
I've moved all this here to save the annoyance of those interested in F1

KnifeEdge_2K1
02-25-2006, 01:23 PM
unlike matra i do not feel a moral obligation to help the stuborn and stupid people of this world ...
so here's my reply ... " You sir are an idiot."

hightower99
02-25-2006, 02:11 PM
I actually like the Revetec concept as it is a new way of getting work out of the reciprocating piston. It certainly has some advantages going for it but well...

It didn't take me long to figure out a way for the revetec engine to work in a inline configuration. The solution I found also meant that they could run an even number of firings per revolution and I would suggest 2 (as in a 2 lobed cam) as this would allow better output speeds and slightly better effciency over a wider range of speeds.

Also it strikes me as odd that nobody has mentioned the most novel part of this system. The fact that the crank assembly translates the linier motion of the piston into rotary motion of the output at peak efficiency faster than a normal crankshaft, making better use of the higher pressure gasses in the chamber. To some of the critics: the 2.9x more torque you keep quoting is actually taken from a comparision between a single firing in a revetec versus a normal engine! the graph for the results is on the website somewhere...


oh and there are engines (mostly rotary) that show pretty large gains in efficiency over the humble piston engine (which has many fundamental flaws) I believe the Quasiturbine a proud canadian invention shows much better innovation and promise.
http://www.quasiturbine.com/QTImages/QTWiki180px.jpg

Matra et Alpine
02-25-2006, 03:05 PM
I had tried to point it out to him "ht", but as you see failed :D
Yeah the Q is another one of the interesting ones around.
I was concerned that it would suffer as the Wankel does of trying to maintain a good cylinder seal. Not seen any protoypes yet.
Btw "French-Canadian" --- so there will be HALF of a flaw in it :D
http://quasiturbine.promci.qc.ca/QTImages/QTSCExc578AnimNet.gif

hightower99
02-25-2006, 03:15 PM
First sealing is no longer an issue for rotary engine like the wankel or Q they figured out what to make them of (aluminium-carbon alloy) and second check out the site (it is in english too!) and you can see a few prototypes...

And I know that it is French canadian and unfortunately I do not fit the stereotypical "I hate Quebec" mindset. I see Quebec as having some of the brightest minds on the planet...

Matra et Alpine
02-25-2006, 03:50 PM
First sealing is no longer an issue for rotary engine like the wankel or Q they figured out what to make them of (aluminium-carbon alloy)
Not sufficient to prevetn some bypass and limiting it's anti-pollution capability.

and second check out the site (it is in english too!) and you can see a few prototypes...
From what I can see the only working ones they are showing are still teh air powered ones. It's takign AGES to try to go throught the numerous vids they seem to have in the hope of one having a detonation engine. Do you have a link to IT ?
PS: j'ai les voitures francaises. J'ai du apprendre comment lire et parler le francais

And I know that it is French canadian and unfortunately I do not fit the stereotypical "I hate Quebec" mindset. I see Quebec as having some of the brightest minds on the planet...
I flew from Ottowa to Calgary once when the in-flight attendant started to repeat in French a guy three rows back shouted out we didnt' need that kind of talk now that we were in Alberta !! The ONLY time I ever saw it surface :D
( Sorry long-standing joke, the French will always have some fatal flaw that undermines the pure perfection :( )

stian1979
02-25-2006, 08:48 PM
The rigid reciprocating piston assembly is not balanced. Sure, the cams are balanced (they would be even if they weren't counter-rotating), but so is a crankshaft. The pistons in a conventional horizontally opposed engine move opposite each other to balance themselves. There are still third order movements, but they are minor. This Revetec engine design is a vibrating mess. Just watch the videos. Anything not rigidly connected to the stand buzzes like crazy whenever the engine is revved.
The rigid reciprocating piston assembly is heavy. All the reciprocating weight from a conventional engine (pistons & connecting rods) are maintained, but in place of lightweight pins we have heavy roller wheels and bearings. At least, they must be pretty heavy in order to transfer combustive force from the piston assembly to the cams. Also, roller wheels, even with strong bearings are subjected to metal-to-metal contact, and will wear accordingly. In comparison, conventional oilled bearing races are lightweight and extremely durable.
The twin counter-rotating cams push back on the pistons just as much as the pistons push on them (according to basic highschool Newtonian physics). This means that the cam follower on one side is pushed hard in the up direction as it follows the top of one cam lobe, while the follower on the opposite side (at the same piston end) is being pressed downward by the other cam lobe. This must result in some significant torque loading on the piston assembly. What's worse is that the direction of the torque load reverses for each and every stroke. I'm curious to know what provides the resistance to the torque loads.
They claim that a conventional engine doesn't acheive crank efficiency until 60deg ATDC. Maximum crank efficiency is where the crank is being pushed by the connecting rod at a tangent to it's travel. They provide some graphs:

.. but provide no information regarding how their device, which never pushes at a tangent to the travel of the cams, is any better. The graphs have no units and I don't see where the obvious mechanical disadvantage of the follower moving towards the axis (shorter lever arm = reduction in torque) is adequately portrayed by the vague green curve on their graph. At the time during the stroke when the piston pressure is the greatest, the piston has the most mechanical advantage, while it has the lowest mechanical advantage when it has the least piston pressure.
As in most engines, the ultimate limit to the rotational speed is the speed that the pistons travel. The folks at Revetec would like to remind you that by altering the cam profile, the maximum speed of the piston can be customized. What they don't tell you is that by altering the rod:stroke ratio and the stroke of a conventional engine will yeild the same changes in engine speed.
If you watch the video where they claim high revs, you can clearly see and hear that the engine is not revving very high. Why is this? Well, in order to get 3 strokes within one revolution, the engine will need to turn at about 1/3rd the speed of a similarly sized conventional engine (assuming both are limited by the maximum piston speed). You may get 3 times the amount of torque out of the Revetec, but you're only doing it with 1/3rd of the powerband... which brings me up to my last niggle:

I hope you're still reading, because this is a riot...

Revetec lists a portion of the articleTorque and Horsepower - A Primer on their website (CCE Design>>Let's Torque) which reads as follows:

Quote:
The Case For Torque

Now, what does all this mean in carland?

First of all, from a driver's perspective, torque, to use the vernacular, RULES :-). Any given car, in any given gear, will accelerate at a rate that *exactly* matches its torque curve (allowing for increased air and rolling resistance as speeds climb). Another way of saying this is that a car will accelerate hardest at its torque peak in any given gear, and will not accelerate as hard below that peak, or above it. Torque is the only thing that a driver feels, and horsepower is just sort of an esoteric measurement in that context. 300 foot pounds of torque will accelerate you just as hard at 2000 rpm as it would if you were making that torque at 4000 rpm in the same gear, yet, per the formula, the horsepower would be *double* at 4000 rpm. Therefore, horsepower isn't particularly meaningful from a driver's perspective, and the two numbers only get friendly at 5252 rpm, where horsepower and torque always come out the same.

In contrast to a torque curve (and the matching pushback into your seat), horsepower rises rapidly with rpm, especially when torque values are also climbing. Horsepower will continue to climb, however, until well past the torque peak, and will continue to rise as engine speed climbs, until the torque curve really begins to plummet, faster than engine rpm is rising. However, as I said, horsepower has nothing to do with what a driver *feels*.

You don't believe all this?

Fine. Take your non turbo car (turbo lag muddles the results) to its torque peak in first gear, and punch it. Notice the belt in the back? Now take it to the power peak, and punch it. Notice that the belt in the back is a bit weaker? Fine.


Wow, great! Torque is king! Power is meaningless!

Well, not really. If you read the article in full, you'll see that just the opposite is true.. only that Revetec would like you stop reading there. I wonder why Revetec doesn't want you know the entire story???

The next article (Why is Torque More Important than Horsepower?)refers to how engines with a lower state of tune are better for daily driving. This is true, we all like low end torque for leaving stoplights behind. What Revetec doesn't remind you is that their engine, spinning at 2000rpm is equivalent to your conventional engine spinning 6000rpm. Even though the output shaft is only spinning at 1/3rd the speed, the pistons are still screaming.

I don't see any real-life advantages to this Revetec engine over a conventional crank driven engine, and as long as Revetec isn't willing to provide any real life data they shouldn't be expecting me (or anyone else) to take stock in their company.


KnifeEdge_2K1 If you are so smart and I'm so stupid why am I the only one that ask questions about this SUPER design? It was something else once many years ago that was suposed to replace all engines in the world. What was the name again? hhmmmmmmmmmmmm think it started with a w and I think some asian car brand still use it in a model or two vx5 sa3 or rx7 some thing like that.

kW=kNm/s has nothing with no loss to do.
If the teoretical torque is 100Nm then the teoretical kW is 100Nm x RPM
If the real torque is 98Nm then the real kW is 98Nm x RPM

If you have 3 times the torque and the same hp it means you have mesured the engines under conditions that can not becompared or you runn designs of top and cylinder that can not be compared. If you runn same bore:stroke ratio and use same design of valves top and manifoil. Seams like you guys claim to be engineers and I am a engineer so I expect you to understand this mutch.

Well how mutch is the loss in bearings? annybody know?

hightower99
02-26-2006, 12:57 AM
Not sufficient to prevetn some bypass and limiting it's anti-pollution capability.
this is not true at all look at the results of the new RX 8 engine and you will see slightly less bypass then a comparable piston motor and that it is quite green. (low pollution without much more than a catalytic converter with an O2 sensor.)

From what I can see the only working ones they are showing are still teh air powered ones. It's takign AGES to try to go throught the numerous vids they seem to have in the hope of one having a detonation engine. Do you have a link to IT ?
There is a movie on the website that is an episode from a french discovery channel and there you see Gilles the inventor starting a IC version of the Q he also cools it off in another seen by dumping some water over it while it is still running! unforunately I do not have a link.

j'ai les voitures francaises. J'ai du apprendre comment lire et parler le francais so you like renaults and Puegeots? and congradulations with being able to read and speak and write french!


Right on to the main attraction:

The rigid reciprocating piston assembly is not balanced. Yes it is balanced but the way it moves will create vibration.

Sure, the cams are balanced (they would be even if they weren't counter-rotating), but so is a crankshaft. first a normal crankshaft is not balanced when it is rotated by its self, it is considered close to being balanced when it has the whole weight of pistons and con-rods and all that. Second the counter rotating bit is not for balance it is to cancel Torqueing of the entire engine when reved! this alone is an improvement and worth about 3 points of overall drive train efficiency!

The pistons in a conventional horizontally opposed engine move opposite each other to balance themselves. There are still third order movements, but they are minor. This Revetec engine design is a vibrating mess. Boxer engines are one of the few configurations that can be perfectly balanced and the revetec does not gain this advantage due to both pistons being rigidly attached and moving as a whole in the same direction every stroke. However this issue is corrected in my design change!

The rigid reciprocating piston assembly is heavy. All the reciprocating weight from a conventional engine (pistons & connecting rods) are maintained, but in place of lightweight pins we have heavy roller wheels and bearings. At least, they must be pretty heavy in order to transfer combustive force from the piston assembly to the cams. Also, roller wheels, even with strong bearings are subjected to metal-to-metal contact, and will wear accordingly. In comparison, conventional oilled bearing races are lightweight and extremely durable. first their is a weight saving if you compare a set of pistons with a set of revetec ones. The weight is saved in the connecting rods that hold the two pistons together because they do not have to be as robust as normal connecting rods. also the pistons can be lighter because they don't need such large skirts to deal with side loading and since when did the bearings have to be "heavy" from your information you can only put forth that they most be tough and solid not heavy! with the roller contact the metal to metal contact occures between two surfaces the are moving in the same direction constantly they will not wera down any faster than any other bearing surface in an engine.

The twin counter-rotating cams push back on the pistons just as much as the pistons push on them (according to basic highschool Newtonian physics). This means that the cam follower on one side is pushed hard in the up direction as it follows the top of one cam lobe, while the follower on the opposite side (at the same piston end) is being pressed downward by the other cam lobe. This must result in some significant torque loading on the piston assembly. What's worse is that the direction of the torque load reverses for each and every stroke. I'm curious to know what provides the resistance to the torque loads. well just look at the engine the pistons are tied together and they are torqued in opposite directions therefore cancelling any vibration. This is also fixed in my design which has 3 lighter 2 lobe counter rotating cams instead of 2 heavier 3 lobed cams.

They claim that a conventional engine doesn't acheive crank efficiency until 60deg ATDC. Maximum crank efficiency is where the crank is being pushed by the connecting rod at a tangent to it's travel. They provide some graphs: Actually they claim that a normal piston makes peak torque (a combination of high cylinder pressure and high coversion) at 60deg ATDC this is generally true.

.. but provide no information regarding how their device, which never pushes at a tangent to the travel of the cams, is any better. The graphs have no units and I don't see where the obvious mechanical disadvantage of the follower moving towards the axis (shorter lever arm = reduction in torque) is adequately portrayed by the vague green curve on their graph. At the time during the stroke when the piston pressure is the greatest, the piston has the most mechanical advantage, while it has the lowest mechanical advantage when it has the least piston pressure.
As in most engines, the ultimate limit to the rotational speed is the speed that the pistons travel.
You obviously haven't looked at this engine have you. The whole advantage of the revetec is that it almost immediately after combustion starts the piston is pushing the cams at a tangent making much more torque. You are however correct in pointing out that the point at which the piston pushes the cam has less and less of a lever as the power stroke goes on. Pressure in the cylinder is greatest close at TDC and alittle after that it starts dropping very quickly, in normal piston engines the high mechanical efficiency is achieved when there is very low cylinder pressure and when there is high cylinder pressure the normal crankshaft is pathetic at making anything of it! well has anybody noticed that the novelty in the revetec engine is that you only need 1/3 the stroke and can therefore attain higher output speeds! The bore:stroke ratio in a revetec shoud be something close to F1 (large bore, short stroke) this allows more area for the valves for better breathing and higher output speeds.

If you watch the video where they claim high revs, you can clearly see and hear that the engine is not revving very high. Why is this? Well, in order to get 3 strokes within one revolution, the engine will need to turn at about 1/3rd the speed of a similarly sized conventional engine (assuming both are limited by the maximum piston speed). You may get 3 times the amount of torque out of the Revetec, but you're only doing it with 1/3rd of the powerband... which brings me up to my last niggle: hmm this is an odd statement. You can hear that the engine is running slowly? (if both the revetec and a normal engine have the same max piston speed then the only thing running at a different speed is the crankshaft, and I don't think you are claiming that you can hear if the crankshaft is turning faster or slower are you?) You are misunderstanding something here I think you meant to say that the revetec gets 3 times more torque but at 1/3 the output speed. this is not true the revetec only claimed that they get 2.9 times more toque per firing not per engine speed!

Hmm that artical you posted was made not by revetec but by someone else trying to market it or something. I agree that it is full of Shite but don't let one misguided soul ruin everything!

BTW has nobody figured out that HP is TorqueXRPM where as Torque is a stationary measure of force? HP is what moves the car!


KnifeEdge_2K1 If you are so smart and I'm so stupid why am I the only one that ask questions about this SUPER design? It was something else once many years ago that was suposed to replace all engines in the world. What was the name again? hhmmmmmmmmmmmm think it started with a w and I think some asian car brand still use it in a model or two vx5 sa3 or rx7 some thing like that. hmmm do you mean the sublime wankel motor in the new RX8? well you shouldn't make fun it has the highest HP/cc of any production naturally aspirated engine it isn't the designs fault that only Mazda had the balls to see the R&D through!

Matra et Alpine
02-26-2006, 05:26 AM
this is not true at all look at the results of the new RX 8 engine and you will see slightly less bypass then a comparable piston motor and that it is quite green. (low pollution without much more than a catalytic converter with an O2 sensor.)
In the UK the Renesis engine is producing 20% MORE emissions and 10% LESS mileage than say the Honda S2000.
it also uses oil, so it would suggest that PART of the improvement in the tip is sacrificial oiling, but the owner at Knockhilll didnt' know much technical stuff :(

There is a movie on the website that is an episode from a french discovery channe
damn, every time I tried to get that one it was freezing half way through :(
Further evidence of Murphy's law.
Cheers I'll try anotehr route to get it.

so you like renaults and Puegeots? and congradulations with being able to read and speak and write french!
Alpines and Matras really :) ( Hence the nic ) My French isnt' good enough when trying to explain a problem in a 25 year old Matra to a French garage owner who is expert on the car but speaks no English !!!! THe A610 is even better(!) as the German tuner speaks no Egnlish, but one of his mechanics speaks French, so we have had some 3-way conversations in a mixture of German ( I understand a little ) and French !!!!!

hmmm do you mean the sublime wankel motor in the new RX8? well you shouldn't make fun it has the highest HP/cc of any production naturally aspirated engine it isn't the designs fault that only Mazda had the balls to see the R&D through!
Definately. Maybe, it was always doomed because of the "equivalence formula" applied to it. After the successes of the Le Mans cars it would have been nice to see it entered in different formulas. So it is those who like "quirky" and "different" who will look at it and enjoy it's smooth revving. When the RX-8 race series was running it was like listening to a bike grid :D

KnifeEdge_2K1
02-26-2006, 12:29 PM
The rigid reciprocating piston assembly is not balanced. Sure, the cams are balanced (they would be even if they weren't counter-rotating), but so is a crankshaft. The pistons in a conventional horizontally opposed engine move opposite each other to balance themselves. There are still third order movements, but they are minor. This Revetec engine design is a vibrating mess. Just watch the videos. Anything not rigidly connected to the stand buzzes like crazy whenever the engine is revved.
The rigid reciprocating piston assembly is heavy. All the reciprocating weight from a conventional engine (pistons & connecting rods) are maintained, but in place of lightweight pins we have heavy roller wheels and bearings. At least, they must be pretty heavy in order to transfer combustive force from the piston assembly to the cams. Also, roller wheels, even with strong bearings are subjected to metal-to-metal contact, and will wear accordingly. In comparison, conventional oilled bearing races are lightweight and extremely durable.
The twin counter-rotating cams push back on the pistons just as much as the pistons push on them (according to basic highschool Newtonian physics). This means that the cam follower on one side is pushed hard in the up direction as it follows the top of one cam lobe, while the follower on the opposite side (at the same piston end) is being pressed downward by the other cam lobe. This must result in some significant torque loading on the piston assembly. What's worse is that the direction of the torque load reverses for each and every stroke. I'm curious to know what provides the resistance to the torque loads.
They claim that a conventional engine doesn't acheive crank efficiency until 60deg ATDC. Maximum crank efficiency is where the crank is being pushed by the connecting rod at a tangent to it's travel. They provide some graphs:

.. but provide no information regarding how their device, which never pushes at a tangent to the travel of the cams, is any better. The graphs have no units and I don't see where the obvious mechanical disadvantage of the follower moving towards the axis (shorter lever arm = reduction in torque) is adequately portrayed by the vague green curve on their graph. At the time during the stroke when the piston pressure is the greatest, the piston has the most mechanical advantage, while it has the lowest mechanical advantage when it has the least piston pressure.
As in most engines, the ultimate limit to the rotational speed is the speed that the pistons travel. The folks at Revetec would like to remind you that by altering the cam profile, the maximum speed of the piston can be customized. What they don't tell you is that by altering the rod:stroke ratio and the stroke of a conventional engine will yeild the same changes in engine speed.
If you watch the video where they claim high revs, you can clearly see and hear that the engine is not revving very high. Why is this? Well, in order to get 3 strokes within one revolution, the engine will need to turn at about 1/3rd the speed of a similarly sized conventional engine (assuming both are limited by the maximum piston speed). You may get 3 times the amount of torque out of the Revetec, but you're only doing it with 1/3rd of the powerband... which brings me up to my last niggle:

I hope you're still reading, because this is a riot...

Revetec lists a portion of the articleTorque and Horsepower - A Primer on their website (CCE Design>>Let's Torque) which reads as follows:

Quote:
The Case For Torque

Now, what does all this mean in carland?

First of all, from a driver's perspective, torque, to use the vernacular, RULES :-). Any given car, in any given gear, will accelerate at a rate that *exactly* matches its torque curve (allowing for increased air and rolling resistance as speeds climb). Another way of saying this is that a car will accelerate hardest at its torque peak in any given gear, and will not accelerate as hard below that peak, or above it. Torque is the only thing that a driver feels, and horsepower is just sort of an esoteric measurement in that context. 300 foot pounds of torque will accelerate you just as hard at 2000 rpm as it would if you were making that torque at 4000 rpm in the same gear, yet, per the formula, the horsepower would be *double* at 4000 rpm. Therefore, horsepower isn't particularly meaningful from a driver's perspective, and the two numbers only get friendly at 5252 rpm, where horsepower and torque always come out the same.

In contrast to a torque curve (and the matching pushback into your seat), horsepower rises rapidly with rpm, especially when torque values are also climbing. Horsepower will continue to climb, however, until well past the torque peak, and will continue to rise as engine speed climbs, until the torque curve really begins to plummet, faster than engine rpm is rising. However, as I said, horsepower has nothing to do with what a driver *feels*.

You don't believe all this?

Fine. Take your non turbo car (turbo lag muddles the results) to its torque peak in first gear, and punch it. Notice the belt in the back? Now take it to the power peak, and punch it. Notice that the belt in the back is a bit weaker? Fine.


Wow, great! Torque is king! Power is meaningless!

Well, not really. If you read the article in full, you'll see that just the opposite is true.. only that Revetec would like you stop reading there. I wonder why Revetec doesn't want you know the entire story???

The next article (Why is Torque More Important than Horsepower?)refers to how engines with a lower state of tune are better for daily driving. This is true, we all like low end torque for leaving stoplights behind. What Revetec doesn't remind you is that their engine, spinning at 2000rpm is equivalent to your conventional engine spinning 6000rpm. Even though the output shaft is only spinning at 1/3rd the speed, the pistons are still screaming.

I don't see any real-life advantages to this Revetec engine over a conventional crank driven engine, and as long as Revetec isn't willing to provide any real life data they shouldn't be expecting me (or anyone else) to take stock in their company.


KnifeEdge_2K1 If you are so smart and I'm so stupid why am I the only one that ask questions about this SUPER design? It was something else once many years ago that was suposed to replace all engines in the world. What was the name again? hhmmmmmmmmmmmm think it started with a w and I think some asian car brand still use it in a model or two vx5 sa3 or rx7 some thing like that.

kW=kNm/s has nothing with no loss to do.
If the teoretical torque is 100Nm then the teoretical kW is 100Nm x RPM
If the real torque is 98Nm then the real kW is 98Nm x RPM

If you have 3 times the torque and the same hp it means you have mesured the engines under conditions that can not becompared or you runn designs of top and cylinder that can not be compared. If you runn same bore:stroke ratio and use same design of valves top and manifoil. Seams like you guys claim to be engineers and I am a engineer so I expect you to understand this mutch.

Well how mutch is the loss in bearings? annybody know?

torque is what determines how fast u accelerate at any given point but ur also forgetting torque at the wheels is what matters and that changes with the gear ratios, power is what ultimately determines speed when all other factors are fixed

you can beef up the torque band and NOT significantly affect the max power
you cant really use the same formula for torque x rpm = power since the revtec engine fires 3 times per revolution of the crank and not 1 per 2 revolution of the crank like a regular piston engine (this is per cylinder)
the revtec is firing 6 times as much as a regular piston engine in the same amount of time

the rev limit on an engine is not determined by how fast the piston moves, its how much stress the conrods can take at the speed the piston moves, its a subtle but important difference, there are no conrods in the revtec engine so the max rpm must be limited by another factor

there so much more thats wrong with what u said i just dont have any time to argue wit hu

stian1979
02-26-2006, 06:11 PM
M=F x l

If you got anny tecnical education I gues you know what this means.
As long as you have a konstand F you can not increase M without making l longer.
If you want 3 times the torque you have to make the diameter of the crank or whatever 3 times larger. This is unless you find a eficiant way of transfering the power to the crank so less energy escape trough the cooling system. but this would mean that they acheved 90% engine efficensy.
40% of the energy don't get used and escape trough the exhaust so this engine is feed with 130%?
It's too mutch things here that don't ad up.




BTW has nobody figured out that HP is TorqueXRPM where as Torque is a stationary measure of force? HP is what moves the car!

Exsactly


hmmm do you mean the sublime wankel motor in the new RX8? well you shouldn't make fun it has the highest HP/cc of any production naturally aspirated engine it isn't the designs fault that only Mazda had the balls to see the R&D through!

I do not make funn of it, but for some time everyone thought it was suposed to end up in every car. It's not even with mazda.


torque is what determines how fast u accelerate at any given point but ur also forgetting torque at the wheels is what matters and that changes with the gear ratios, power is what ultimately determines speed when all other factors are fixed

you can beef up the torque band and NOT significantly affect the max power
you cant really use the same formula for torque x rpm = power since the revtec engine fires 3 times per revolution of the crank and not 1 per 2 revolution of the crank like a regular piston engine (this is per cylinder)
the revtec is firing 6 times as much as a regular piston engine in the same amount of time

the rev limit on an engine is not determined by how fast the piston moves, its how much stress the conrods can take at the speed the piston moves, its a subtle but important difference, there are no conrods in the revtec engine so the max rpm must be limited by another factor

there so much more thats wrong with what u said i just dont have any time to argue wit hu

Piston speed is what sets the limits. If you want to go beond this limits you have to find a fuel that burn faster. If you look at low rpm engines and high rpm engines they got the same piston speed. You bether don't argue with me since you are only making a fool out of yourself.


Boxer engines are one of the few configurations that can be perfectly balanced and the revetec does not gain this advantage due to both pistons being rigidly attached and moving as a whole in the same direction every stroke. However this issue is corrected in my design change!


To stopp the vibration caused from the two pistions moving the same way they have to use balance shafts and then one of fatastic advantages is gone. It has the same counter weihts as a normal engine

The australians have this strange designs that is going to save the world, did annyone see the crankless engine? I would not call it that, but more like a aksial crank. All forces from the pistion is transfered trough a trust bearing.


To be honest I like the Sytec engine design bether.
www.cmcpower.com

Matra et Alpine
02-26-2006, 06:33 PM
To stopp the vibration caused from the two pistions moving the same way they have to use balance shafts and then one of fatastic advantages is gone. It has the same counter weihts as a normal engine
THIS was covered before.
A boxer has OPPOSING pistons and so s self-balanced.
You are confusing a V180 configuration.

The australians have this strange designs that is going to save the world, did annyone see the crankless engine? I would not call it that, but more like a aksial crank. All forces from the pistion is transfered trough a trust bearing.
There are quite a few different ideas coming out of Australia just now and Canada - must be all those immigrant Scots :D.
Of course you can go back to 1930 and Bourke's design -- whcih I see is being resurrected again :D

To be honest I like the Sytec engine design bether.
www.cmcpower.com (http://www.cmcpower.com)Each have advantages/disadvatages. As long as you are as critical and honest :D
Me ? I would LOVE to see the Rand Cam engine work. Now THAT is thinking different :D 24 combustion events per rotation :D
As was said before, there are LOTS of clever an innovative designs coming out and being prototyped for full evaluation.

KnifeEdge_2K1
02-26-2006, 06:44 PM
M=F x l

If you got anny tecnical education I gues you know what this means.
As long as you have a konstand F you can not increase M without making l longer.
If you want 3 times the torque you have to make the diameter of the crank or whatever 3 times larger. This is unless you find a eficiant way of transfering the power to the crank so less energy escape trough the cooling system. but this would mean that they acheved 90% engine efficensy.
40% of the energy don't get used and escape trough the exhaust so this engine is feed with 130%?
It's too mutch things here that don't ad up.



Piston speed is what sets the limits. If you want to go beond this limits you have to find a fuel that burn faster. If you look at low rpm engines and high rpm engines they got the same piston speed. You bether don't argue with me since you are only making a fool out of yourself.



you do know that's the formula for work ... if the engine fires 3 times as much as a regular engine then it will produce 3 times the work at the same rpm

piston speed isnt determined by rpm alone, the stroke needs to be taken into account, thats why f1 engines can reach 19000 rpm
and its not the pistons that limit the rpm its the conrods, the piston isnt what's going to give first, thats the conrods, there are no conrods in the revtec engine

stian1979
02-26-2006, 08:28 PM
THIS was covered before.
A boxer has OPPOSING pistons and so s self-balanced.
You are confusing a V180 configuration.

Yes a boxer is self-balanced, but the revetec is not. the pistons here move the same way and are not moving against eatch other like a boxer. It neads balance shafts with counter weights.


you do know that's the formula for work ... if the engine fires 3 times as much as a regular engine then it will produce 3 times the work at the same rpm

Yes so what is the magic of 2,9 times the torque when you nead 3 times the work cycles to perform it?


piston speed isnt determined by rpm alone, the stroke needs to be taken into account, thats why f1 engines can reach 19000 rpm
and its not the pistons that limit the rpm its the conrods, the piston isnt what's going to give first, thats the conrods, there are no conrods in the revtec engine

Different explosesivs have diferent detonation speed, what fuel will you use to make the revetec spin at 19000rpm?

TNT has a detonation speed of 7,7km/s or was it nitroglyserin?

When F1 cars was reatching 14000RPM they got problems with valve flow.
This problem was solved by using praumatic springs.

Also they use short stroke/larger bore to get biger valve area per/ccm

You will come into alot of other problems in reatching higher pistionspeed than conroads.

If you look at a huge two stroke diesel with 90RPM and a smal cummins diesel with 2100RPM you will see the piston speed is about the same, 9m/s if I remember corectly.

F1 is a milion dollar industry, if conrods was a problem for RPM torque and horcepower they would find a sulution a long time ago.

If you blow a gasket in the top, how long will those conection pins last? will they just snap and the pistion go straight trough the top?

KnifeEdge_2K1
02-26-2006, 08:59 PM
Yes a boxer is self-balanced, but the revetec is not. the pistons here move the same way and are not moving against eatch other like a boxer. It neads balance shafts with counter weights.



Yes so what is the magic of 2,9 times the torque when you nead 3 times the work cycles to perform it?



Different explosesivs have diferent detonation speed, what fuel will you use to make the revetec spin at 19000rpm?

TNT has a detonation speed of 7,7km/s ot was it nitroglyserin?

When F1 cars was reatching 14000RPM they got problems with valve flow.
This problem was solved by using praumatic springs.

Also they use short stroke to get biger valve area per/ccm

You will come into alot of other problems in reatching higher pistionspeed than conroads.

F1 is a milion dollar industry, if conrods was a problem for RPM torque and horcepower they would find a sulution a long time ago.

If you blow a gasket in the top, how long will those conection pins last? will they just snap and the pistion go straight trough the top?

i never said the revtec could reach 19000 rpm tho, im just using f1 engines as an example because they run on pump ... well nearly pump gas as well
yeah they get problems with the valves but thats cuz they dont rebound as fast and "jump" is the term if iirc, the detonation speed of the fuel isnt the limiting factor

but actually after you brought up those points im beginning to see ur side of the argument, never thought about it that way, since it is producing 3 times the torque at 1/3rd the rpm with 3 times the number of detonations per unit time ... doesnt seem to be so amazing no more ... :(

stian1979
02-26-2006, 09:33 PM
There is alot of things out there.

New ways of transfering work from combustion to rotation.
www.revetec.com
www.quasiturbine.com
www.cmcpower.com (I kind of like this one myself even it has the balance problem)
www.splitcycle.com.au

Some guys trying to make V configuration with Scotch Yoke cycle www.sliderengine.com

New top and valve designs.
www.jack-brabham-engines.com
www.coatesengine.com/index.html
www.rcvengines.com
www.new4stroke.com

Thanks Matra et Alpine I have totaly forgoten about the rand cam.
I was looking at it some years ago.
www.regtech.com

and then the MYT engine that I stil don't quite understand, but there must be some gears that prevent the pistions to return so will that be a problem for reabilety?
www.plug2work.com/angellabsllc/index.html

This one is simpe
www.archerengine.dabsol.co.uk/detail.htm

What is up with the australians and crankshafts?
The all mighty australian crank less engine (aksial crank I would call it)
http://i43.photobucket.com/albums/e353/stian1979/bxtai0489t.jpg
http://i43.photobucket.com/albums/e353/stian1979/crankless-figure.jpg
http://i43.photobucket.com/albums/e353/stian1979/crankless80cm.jpg


I know what you mean. I newer like the layout, but I was impresed about the torque until those same facts was put into my mind by a arguement.

I was born in hospital and driven home in a Otto driven car and I do belive the basic same layout will drive me to the grave. I think maybe more complex and exspensive systems like compund engines and turbos to recover heat loss and more ceramicswitch to prevent heat loss will be adopted. This is the main problems the combustion engine and when oil become so exspensive that consumors are willing to pay for the tecnology it will probartly hapend.

Maybe I'm wrong and I have ben convinced manny times that I am, but In the end I go back to my orginal opinion.

Matra et Alpine
02-27-2006, 05:22 AM
What is up with the australians and crankshafts?
The all mighty australian crank less engine (aksial crank I would call it)
It's words that rhyme with wank that cause them problems.
It goes back to childhood and being caught at it :D

Maybe I'm wrong and I have ben convinced manny times that I am, but In the end I go back to my orginal opinion.
The list was the only point I was trying to make at the start. There are lots of good ideas begng tested to see if they bring a discernible benefit. The prototypes are the only way to ultimately prove/disprove if the increase is achieved in the real world. The markets will decide :D
PS: Good chance you'll get driven there in an electric hybrid, so only half an Otto :D
PPS: Quick patent idea. Use the energy from combustion of the human body to drive a Stirling engine. Load your body in at your home and deliver the ashes at the internment. Zero energy cremations :) Thin people have to be interned close to home :D

stian1979
02-27-2006, 07:52 AM
Stirling engine has a limited use since it can't take quick changes in load.
Electric hybrids is something I don't belive in it's more about what the green consumer want to buy. More weight to pull around and you have loss in electric generator and engines. I got more belife in a engine running at constant rpm and a CVT gearbox.

Stirling hybrid could be interestin. A convensional combustion engine taking care of aceleration and a stirling to recover heat. When the heat transfere to the stirling has made it take load the combustion engine will deload. Replace the traditional radiator by a stirling.

Lot's of things still not tryed just waiting for someone to fail or rice to glory.
One thing I'm shure of is that transfering the liniar motion into rotary the development is allready don 100 times in the past and we would come a long way if those guys around used there energy on heat recovery instead of solving problems that don't eksists.

Matra et Alpine
02-27-2006, 08:36 AM
Stirling engine has a limited use since it can't take quick changes in load.
The point is you would use a Stirling to generate electrical power and use an electric motor to provide htre driven poiwer. The high efficiency possibly with Stirlings amkes it not as inefficient as with ICEs. Why woudl ANYOEN think to use a Stirling direct drive ??? it takes a HUGE piston to generate enought torque to be usable !!!!

Electric hybrids is something I don't belive in it's more about what the green consumer want to buy. More weight to pull around and you have loss in electric generator and engines. I got more belife in a engine running at constant rpm and a CVT gearbox.
With in-wheel motors you save significant mechanical losses that make up for the weight ( which is coming down each year ).
CVTs are very innefficient for heavy vehicles as they require high forces to prevent slip :( High forces then gives higher frictional losses.

Stirling hybrid could be interestin. A convensional combustion engine taking care of aceleration and a stirling to recover heat. When the heat transfere to the stirling has made it take load the combustion engine will deload. Replace the traditional radiator by a stirling.
You'd be more efficient just providng a high efficiency burner heating the heat end of the Stirling. Burners can get 98% efficient an ICE to generate the heat by scavenging still can't get near the theoretical numbers of an efficient Stirling.

Lot's of things still not tryed just waiting for someone to fail or rice to glory.
One thing I'm shure of is that transfering the liniar motion into rotary the development is allready don 100 times in the past and we would come a long way if those guys around used there energy on heat recovery instead of solving problems that don't eksists.
But you STILL keep ignoring the Rvetec solution to opposing piston issue :)
Let's try one last time to get you to understand it.
Linear balance is OK in an engine as you can readily balance that out. Cranks give vector forces and you still ignore those in your comparisons :D
So the linked piston of a Revetec or Bourke et al all are easily balanced as it only moves linearly. Trying to make a weight on rotating cranks plus linear motion piston balance out is what hurts "normal" engines :D
Draw the vector force diagrams for a crank and non-crank engine and you'll understand. A lot of work for gudgeon, conrod and crank for the full cycle but clearly you need to do it to grasp the other forces you're ignoring and minimising even though they are BIG issues in engines
So you are miossing the point when you say these things don't exist !!!

stian1979
02-27-2006, 09:25 AM
The point is you would use a Stirling to generate electrical power and use an electric motor to provide htre driven poiwer. The high efficiency possibly with Stirlings amkes it not as inefficient as with ICEs. Why woudl ANYOEN think to use a Stirling direct drive ??? it takes a HUGE piston to generate enought torque to be usable !!!!

With in-wheel motors you save significant mechanical losses that make up for the weight ( which is coming down each year ).
CVTs are very innefficient for heavy vehicles as they require high forces to prevent slip :( High forces then gives higher frictional losses.

You'd be more efficient just providng a high efficiency burner heating the heat end of the Stirling. Burners can get 98% efficient an ICE to generate the heat by scavenging still can't get near the theoretical numbers of an efficient Stirling.

But you STILL keep ignoring the Rvetec solution to opposing piston issue :)
Let's try one last time to get you to understand it.
Linear balance is OK in an engine as you can readily balance that out. Cranks give vector forces and you still ignore those in your comparisons :D
So the linked piston of a Revetec or Bourke et al all are easily balanced as it only moves linearly. Trying to make a weight on rotating cranks plus linear motion piston balance out is what hurts "normal" engines :D
Draw the vector force diagrams for a crank and non-crank engine and you'll understand. A lot of work for gudgeon, conrod and crank for the full cycle but clearly you need to do it to grasp the other forces you're ignoring and minimising even though they are BIG issues in engines
So you are miossing the point when you say these things don't exist !!!

If you use a electric engine it will require more power when you acelerate.
To suply more power the load on the stirling has to increase and because of the stirlings slow response to load changing it would drop in speed (just read about diesel generator's and speed drop).
A battery package would prevent this, but ad extra weight.

Williams F1 made a CVT in 1994 to be used in racing, but CVT was baned when FIA found out what Sir Frank was up to, but the tecnology to make CVT handle 700Hp is out there.

Yes it's easy to balance it, but it require a balance shaft and this consume power and ads weight to the construction and I'm stil woried about the bearing.

And I don't belive they can put out more torque with the same cylinder preshure, bore and stroke. Let me explain this in a drawing

http://i43.photobucket.com/albums/e353/stian1979/torqueandbearing.jpg

If I got to chose the engine design in my car I know what I would do.
It's a two stroke so It neads seperate cylinder lubrication yes, but it's just soo cool

http://i43.photobucket.com/albums/e353/stian1979/Napier_deltic_animation.gif

And with compund where you can inject fuel into the exhast to get some extra hp out of the turbine when neaded

http://i43.photobucket.com/albums/e353/stian1979/Napier_Nomad.jpg

The smal english companys really know how to make engines, to bad they are gone or close to.

Matra et Alpine
02-27-2006, 10:01 AM
If you use a electric engine it will require more power when you acelerate.
To suply more power the load on the stirling has to increase and because of the stirlings slow response to load changing it would drop in speed (just read about diesel generator's and speed drop).
A battery package would prevent this, but ad extra weight.
Correct, but if it is only required for short periods it does NOT as large a penalty. It's only needed for averaging the peak needs with the average output of a VERY efficient engine. I thought that was obvious :(

Williams F1 made a CVT in 1994 to be used in racing, but CVT was baned when FIA found out what Sir Frank was up to, but the technology to make CVT handle 700Hp is out there.
Careful.
DAF had been racing the CVT in F3 ( with no great success with the layout ) - we've talked about it before on UCP with pics - and Frank worked with them to design a new one and TEST it. Whether it actually delivered any benefit for the weight and stresses was never published and the FIA banned it before it
DC test drove the one in '93
http://8w.forix.com/altpower/williamscvt.jpg

The FIA banned CVT as they felt it took away from the driver. Not for technical reasons. So it never went any further. So we never knew whether it was able to handle the torque lash of kerbs corner on full throttle or if it lasted 2 hours.

Where did you find a reference to it actually HANDLING the 700HP for duration ???


Yes it's easy to balance it, but it require a balance shaft and this consume power and ads weight to the construction and I'm stil woried about the bearing.
It's NOT easy to "balance" an engine. Even the best balancer shafts have recognised frequencies in the engine where they are ineffective due to harmonics.
But the Revetec doesn't' need contra-rotating balanceshafts as it isnt' trying to balance a ROTATING mass. You dint' seem to grasp the difference :)

And I don't belive they can put out more torque with the same cylinder preshure, bore and stroke. Let me explain this in a drawing
By the time you get to the point in the curve you have used up ( or should have ) the expansion of the gasses - with a little left over to assist exhaust flow ). So you are mathematically correct if you were running an engine driven by compressed air. But you're not. You are running a COMBUSTION engine which has a peak pressure which drops as the piston recedes. As I said before, you seem to only see one thing at a time. Each thing on it's own is valid. BUT when you take the other factors into account aren't .

oh and your bearing PROVES you didnt' bother reading. It does NOT matter how long a bearing is it only matters how large the mating surface is. What is too difficult for you to grasp that ??

The smal english companys really know how to make engines, to bad they are gone or close to.
They're not. There are plenty of companies producing new engines on a regular basis.
PS: 2-strokes can't clean up emissions without major post combustion management. You can't burn heavy lubricating oils without emission problems. Sadly nobody wants to invest in finding solutions.

stian1979
02-27-2006, 10:53 AM
[quote=stian1979]If you use a electric engine it will require more power when you acelerate.
To suply more power the load on the stirling has to increase and because of the stirlings slow response to load changing it would drop in speed (just read about diesel generator's and speed drop).
A battery package would prevent this, but ad extra weight.[/quote}
Correct, btu if it is only required for short periods it does NOT as larege a penalty. It's only needed for averaging the peak needs withthe average output fo a VERY efficient engine. I thought that was obvious :(

Careful.
DAF had been racing the CVT inf F3 - we've talked abotu it before on UCP with pics - and Frank worked with them to TEST it. Whether it actually delevered any benefit for the weight and stresses was never published and the FIA banned it before it
DC test drove the one in '93
http://8w.forix.com/altpower/williamscvt.jpg

The FIA banned CVT as they felt it took away from the driver. Not for technical reasons. So it never went any further. So we never knew whether it was able to handle the torque lash of kerbs corner on full throttle or if it lasted 2 hours.

Where did you find a reference to it actually HANDLING the 700HP for duration ???


It's NOT easy to "balance" an engine. Even the best balancer shafts have recognised frequencies in the engine where they are inneffective due to harmonics.
But the Revetec doesnt' need contra-rotating balanceshafts as it isnt' trying to balance a ROTATING mass. You dont' seem to grasp the difference :)

By the time you get to the point in the curve you have used up ( or should have ) the expansion of the gasses - with a little left over to assist exhaust flow ). So you are mathematically correct if you were running an engine driven by compressed air. But you're not. You are running a COMBUSTION engine which has a peak pressure which drops as the piston recedes. As I said before, you seem to only see one thing at a time. Each thing on it's own is valid. BUT when you take the other factors into account aren't .

They're not. THere are plenty of companies producing new engines on a regular basis.
PS: 2-strokes can't clean up emissions without major post combustion management. You can't burn heavy lubricating oils wihtout emission problems. Sadly nobody wants to invest in finding solutions.

DC put in some impresive lap times with the CVT in testing.

To acelerate a famely van it take some power so batterys had to have a size that would ad weight and take away space. A famely car of some size 1500kg from 0-100km/h in 11 secs nead some power and if you got batterys fully loaded and acelerate to 80km/h and a dude runn into the road so you got to brake. Then you step on it again and at 90km/h the car just die because batterys are runn empthy and the stirling stil did not get up too speed yet so you are limited to 50km/h and slovly acelerating until you reatch 100km/h.

I got more belif that it has to be combined with a traditional combustion engine. Maybe a combustion engine only enabled on city driving and aceleration, disabled during freeway. who konw.

So with out balance shafts, how will you make the forces from the pistons not to ad vibration? This is not a boxer in case you did not notice so both pistons move toward's the same side at the same time. If the engine was constructed without conrods just like the revetec is and at the same time was able to make pistons move towards eatch other like a boxer no balancing would be required. Since the crankshaft rotate 1 per 3 work cycles counter weights can not be added to this, some thing you see is obious so it will nead a balance shaft to balance out the oscilating movements from pistions. Rotating alancing is not a problem like the traditional conrods I can agree.

1/2 of the conrod is considered to be oscilating and the other 1/2 is considered to be rotating. I did my homework on this, probartly the only thing about engine dynamics I still remember.

2-strokes are the moust inviromental engines. You don't find anny engine more fuel efficiant than sulzer or B&W 2-strokes. consumtion of cylinder lube oil is a problem caused by the fact that no syntetic oil is made for this purpose. No ship owner want to buy syntetic oil for this purpose since it will cost him soo mutch that he's compatitors will get the contracts.

About cylinder preshure I'm right. Even the preshure drops by 50% I will stil have 50% longer arm than the revetec. It all ends up in the same in the end. The only advantage by geting long arm at a earlier stage is that not that mutch energy has escaped trough the top and cylinderwals yet, but this problem is smal and will be solved at once the customers are willing to pay for cheramic and insolated engines due to fuel prices. There is no practical reason for adapting this design. I like it, it's a funn concept, but it's also all it is.

I'm stil concerned about the bearing. Not anny ball bearing is 100% round, maybe it is 99,9999999%, but not 100% ball barings don't handle the same load as a plain baring and if anny contamination in the oil like soot or other particles it will just dig into the plain bearing and do no futher harm.
A ballbearing can more easely get permanent problems witch I'm shure you are avear off.

Matra et Alpine
02-27-2006, 11:13 AM
[quote=Matra et Alpine]

DC put in some impresive lap times with the CVT in testing.
You got any actual figures.
All that I remember about it was platitudes.
ANd nobody says theire idea is a dog :)

To acelerate a famely van it take some power so batterys had to have a size that would ad weight and take away space. A famely car of some size 1500kg from 0-100km/h in 11 secs nead some power and if you got batterys fully loaded and acelerate to 80km/h and a dude runn into the road so you got to brake. Then you step on it again and at 90km/h the car just die because batterys are runn empthy and the stirling stil did not get up too speed yet so you are limited to 50km/h and slovly acelerating until you reatch 100km/h.
You are AGAIN thinking of only one issue at a time>
The problem is only when you first start up. AS SAID, you would size the battery to manage the peak. You dont' accelerate a car for 20 seconds :D
Sorry but you're missing the whole point by being single-thinking. Build in what the Stirling engien is doing durign the acceleration of the vehicle and what it is doing durign coast and steady speed ?
Nobody's sayign there are NO batteries but it wouldn't need the SHED LOAD that current hybrids are running :D

I got more belif that it has to be combined with a traditional combustion engine. Maybe a combustion engine only enabled on city driving and aceleration, disabled during freeway. who konw.
Even if allowed to run at optimim efficiency, then an Otto will be WELL short of the efficiency of a Stirling -- or another "imporoved" combustion engien :D

So with out balance shafts,
First balancer shafts are requried because of the ROTATION rpbblems.
Do you grasp that ?
So it is ONLY reciprocating weight that is the problem and the only part of a Revetec is the PISTON -- no strong conrod or crank out there :)
So you first recognise that it's a fraction of teh nromal engien weight. So you've done THE MOST IMPORTANT step already which is minimising the mass. Then if necessary they would apply for balance by multiple cylinders -- jstu in teh same way a V8 manages optmimum any paired Revetec piston seupt should.

1/2 of the conrod is considered to be oscilating and the other 1/2 is considered to be rotating. I did my homework on this, probartly the only thing about engine dynamics I still remember.
That's a simplification that only works as long as you're not trygin to maximise the power output or the efficiency. Sadly I believe you've forgotten more than you think :D

2-strokes are the moust inviromental engines.[/quote}
BS and you provide the answer yourself - as I had already said.
[quote]consumtion of cylinder lube oil is a problem caused by the fact that no syntetic oil is made for this purpose.
Rubbish :) You can't make an oil have long chains to maxinmise lubrication AND burn efficiently. You are thinking of only one thing at a time again.
let's now jsut save me the hassle. You're wrong.

About cylinder preshure I'm right. Even the preshure drops by 50% I will stil have 50% longer arm than the revetec. It all ends up in the same in the end.
NO it doens't !!!
You are wrong.,
You are NOT thinking of the whole system again>
A crank does not match the optimal piston pressures because of the angles !! This is what the Revetec designer ( and many others over hte decades ) is trying to recover energy better.
Sorry, think about the CRANK positin as well as piston and do the vector force calucaltion and see how much is goin in to provide OUTPUT force.

There is no practical reason for adapting this design. I like it, it's a funn concept, but it's also all it is.
Because you've NOT actually looked at the force vectors in all the components.
Do it, you will learn and understand.

I'm stil concerned about the bearing. Not anny ball bearing is 100% round, maybe it is 99,9999999%, but not 100% ball barings don't handle the same load as a plain baring and if anny contamination in the oil like soot or other particles it will just dig into the plain bearing and do no futher harm.
A ballbearing can more easely get permanent problems witch I'm shure you are avear off.
Yeah but why is a ball bearing coming in to it ?
Do you mean NEEDLE bearings ?
Needle bearings can handle the pressures.
I think you are still thinking of only one thing at a time. Different materials could provide it, perhaps sacrificial. Oil bath coud deliver it at higher speeds onto the mating surface. WOudl still need strong material tho as it won't benefit from pressure build up from rotation the way a crank does.
But as you are not clearly aware the forces beign talked abotu are the SAME as a normal Gudgeon Pin on a piston is handling :D
So how come it survives there and yet won't here ??
MATERIALS and oil supply -- the challenge will be having ENOUGH pressure to ensure a minium thicnkess of oil to ride on.

hightower99
02-27-2006, 12:35 PM
Actually Matra the most efficient ICE in the world is a super huge 2 stroke diesel.

other than that Matra has done a good job pointing out innaccuracies I just like the fact that I have a design change that could allow the revetec to do so much better (reducing vibration, increase output speed, Improve lever length, lower weight, and it might just improve combustion?)

Matra et Alpine
02-27-2006, 02:54 PM
Actually Matra the most efficient ICE in the world is a super huge 2 stroke diesel.
Yeah but this isn't ultimateSHIPpage.com despite some of Matt's recent postings :D And ships can put huge scrubbers in the exhaust !!
One of the most efficient two strokers was the 1960s Honda 50cc race engine.
Revved to 24,000 needed 12 gears to be usable but SOUNDED SUPERB :D

stian1979
02-27-2006, 08:03 PM
You got any actual figures.
All that I remember about it was platitudes.
ANd nobody says theire idea is a dog :)

You are AGAIN thinking of only one issue at a time>
The problem is only when you first start up. AS SAID, you would size the battery to manage the peak. You dont' accelerate a car for 20 seconds :D
Sorry but you're missing the whole point by being single-thinking. Build in what the Stirling engien is doing durign the acceleration of the vehicle and what it is doing durign coast and steady speed ?
Nobody's sayign there are NO batteries but it wouldn't need the SHED LOAD that current hybrids are running :D

Even if allowed to run at optimim efficiency, then an Otto will be WELL short of the efficiency of a Stirling -- or another "imporoved" combustion engien :D

First balancer shafts are requried because of the ROTATION rpbblems.
Do you grasp that ?
So it is ONLY reciprocating weight that is the problem and the only part of a Revetec is the PISTON -- no strong conrod or crank out there :)
So you first recognise that it's a fraction of teh nromal engien weight. So you've done THE MOST IMPORTANT step already which is minimising the mass. Then if necessary they would apply for balance by multiple cylinders -- jstu in teh same way a V8 manages optmimum any paired Revetec piston seupt should.

That's a simplification that only works as long as you're not trygin to maximise the power output or the efficiency. Sadly I believe you've forgotten more than you think :D
2-strokes are the moust inviromental engines.
BS and you provide the answer yourself - as I had already said.

Rubbish :) You can't make an oil have long chains to maxinmise lubrication AND burn efficiently. You are thinking of only one thing at a time again.
let's now jsut save me the hassle. You're wrong.

NO it doens't !!!
You are wrong.,
You are NOT thinking of the whole system again>
A crank does not match the optimal piston pressures because of the angles !! This is what the Revetec designer ( and many others over hte decades ) is trying to recover energy better.
Sorry, think about the CRANK positin as well as piston and do the vector force calucaltion and see how much is goin in to provide OUTPUT force.

Because you've NOT actually looked at the force vectors in all the components.
Do it, you will learn and understand.

Yeah but why is a ball bearing coming in to it ?
Do you mean NEEDLE bearings ?
Needle bearings can handle the pressures.
I think you are still thinking of only one thing at a time. Different materials could provide it, perhaps sacrificial. Oil bath coud deliver it at higher speeds onto the mating surface. WOudl still need strong material tho as it won't benefit from pressure build up from rotation the way a crank does.
But as you are not clearly aware the forces beign talked abotu are the SAME as a normal Gudgeon Pin on a piston is handling :D
So how come it survives there and yet won't here ??
MATERIALS and oil supply -- the challenge will be having ENOUGH pressure to ensure a minium thicnkess of oil to ride on.

No I'm not thinking at one thing at the time, but you are or like to think I am.

If you during aceleration neads to brake down because of a unekspected event and the acelerate again, your batteries would runn empthy befour the stirling would be able to take the load. Why do you think your so smart? don't you think there would be a hybrid stirling on someones model program allready if it was sutch a smart idea or are you one of those that belive there is a big conspiracy to keep up the oil price and sale?

A stirling is relative easy to build and sheap so it's clearly not a good idea since no one used it. I only see them as a way of energy recovery. Maybe you think that this hybrid thing is a new thing, but in the shipindustrie diesel generators running electric motors are a old idea from 1940. It only have advantage in load changing contitions and If the Stirling was a great idea This is probartly the place it would pop up first.

Yes I do understand that 1/2 and 1/2 is the simplefyed version, but do I really have to feed you everything in detail?
I understand why we got balance shafts and I also understand why counter weights are added to the crank. It's to counteract oscilating forces from the piston and 1/2 of the conroad(simplefyed version) How do you plan to fitt them to a revetec crank??? How will you counteract forces with a counter weight on a shaft rotating 1 time for every 6 time the force is aplied?
If you had a 4-cyl the engine would twist so to make vibrations not bother driver or/and pasangers you would nead a flat 8 who the hell would put that into there car?Packaging like you have pointed out yourself.
Just in case you stil don't understand the diference bewen a boxwe and a revetec.
http://i43.photobucket.com/albums/e353/stian1979/boxervsrevetec.jpg
Packaging like you have pointed out yourself.

Nedle bearing's solve one problem, but only one. They still are not that happy about contamination in the oil unlike plain bearings that can handle some of it. They are just like the ballbearing not 100% round and you ad two new disadvantages and that is that they can't handle that high speed's and if they go wrong they can relly go wrong.
If you want to adapt plain bearing's for this aplication how would you do that? How do you want to make the surface big enough to get a hydrodynamical lubrication that will not brake. Maybe you think I only think at one thing at the time and I think you come up with problems instead of sulutions.

Again there is no gain in this construction. The only smal gain is that it can make heat from combustion into work befour it transmits into the cooling system. This is a peoblem that will be solved annyway when the fuel price make ceramics worth there price. I can also ad to the discusion that fuel don't exsplode, but it combust. At the time 40-50% of the stroke is done it's stil hydro carbons burning and ading energy and at this time the convencional crank is at it's maximum angle. so this is energy the revetec will transforme into rotation when it has only 50% of it's optimal angle.

1-1=0

P.S clearly your knowledge about 2-strokes is limited to Honda MB-5 and Yamaha DTR-50.
Did you hear about Cumer, Wickmann, B&W, Sulzer, Detroit Diesel or GM Diesel at all?
About the lubrication oil for cylinders You defently not know what this is about, do you really think that all two strokes use oil mixed in there fuel? Worng! as for using syntetic oil I actualy atended a cource with Mobil Oil where use and qualety of oil's where the ishue. If you can use a syntetic oil you can get a bether lubrication so you can use less oil to do the same job and that will my friend reduce the problem of burned oil. Do some back ground studys befour opening you mouth.

stian1979
02-27-2006, 09:23 PM
Lets say you are corect about the revetec. It delivers 3times the torque.:p

If a normal engine has a 30% efficensy and the revetec is able to transform 3 times more of the combustion into torque it would mean a efficensy of 90%
WOW!:eek:

I can actualy use the cooling water to wash a babys but and put my balls on the headers without feeling anny discomfort. :rolleyes:

hightower99
02-28-2006, 03:41 AM
Yeah but this isn't ultimateSHIPpage.com despite some of Matt's recent postings And ships can put huge scrubbers in the exhaust !!
One of the most efficient two strokers was the 1960s Honda 50cc race engine.
Revved to 24,000 needed 12 gears to be usable but SOUNDED SUPERB

What??? I don't think so they guzzeled gas and oil like crazy for thier power output! The super large diesel I am talking about can reach 50% thermal efficiency!

Why is everybody still thinking about Stirlings and ceramic composites??? really people those are the old guesses at how to solve the heat problem but I know of a much better solution. A no-loss water injection system! inject water just as ignition is starting and most of the heat will be transformed into greater pressure, then you can have a lighter block and no radiators. (I hope everybody realises that it is not the heat but the pressure that makes things go round)

about the revetec vibrating too much, stian1979: the revetec can be made so that the pistons move just like in a normal boxer! (without all the side loading of course!)


Again there is no gain in this construction.
this statement is full of bologna! There is quite a nice gain in the revetec construction (flawed as it is)

The only smal gain is that it can make heat from combustion into work befour it transmits into the cooling system. This is a peoblem that will be solved annyway when the fuel price make ceramics worth there price.this statement shows that you misunderstand where the advantage lies in the revetec. Revetec is better because it transforms reciprocating motion into rotary motion at greater efficiency when there is much higher pressures in the cylinder! In fact it has a higher conversion efficiency at all times! The revetec represents a mechanical change to get higher mechanical efficiency, nowhere does it say that suddenly more heat is made into work (this is not how ICEs work!) And ceramics wil not change the world at all as it doesn't stop the heat from getting out anyways (ever heard of an exaust valve?)


I can also ad to the discusion that fuel don't exsplode, but it combust. At the time 40-50% of the stroke is done it's stil hydro carbons burning and ading energy and at this time the convencional crank is at it's maximum angle. so this is energy the revetec will transforme into rotation when it has only 50% of it's optimal angle.
This is an irrelavant and partially untrue statement. A good engine will combust more than 80% of the fuel in the cylinder before 20 deg ATDC the remaining power from the remaining gas is not enough to keep the pressure high through the expansion phase!(in other words the remaining gas doesn't add any power it simply slows the loss) Most conventional crank engines reach maxium conversion efficiency at around 60deg not 90deg like you think they do. And what are you talking about 50% of it's optimum angle?? the optimum angle is 90deg to radius this doesn't change for any engine! the revetec is always at about 90deg to the radius of the lever arm! (actual range is about 75-90deg when the piston is moving)


Lets say you are corect about the revetec. It delivers 3times the torque.

If a normal engine has a 30% efficensy and the revetec is able to transform 3 times more of the combustion into torque it would mean a efficensy of 90%
WOW!

I can actualy use the cooling water to wash a babys but and put my balls on the headers without feeling anny discomfort.
this is about as missled as I care to read. the 30% efficiency you are talking about in a normal engine is the thermal energy. (as in theretical total energy of fuel used divided by the output energy) the revetec is 3 times more mechanically efficient not thermally! you are relating numbers and doing top of the head math that shouldn't be! Both the revetec and a normal engine have the same amount of waste heat!

Matra et Alpine
02-28-2006, 04:26 AM
What??? I don't think so they guzzeled gas and oil like crazy for thier power output!
No they didnt'.
They competed the Isle of Man TT race on the SAME FUEL as their competitors and did it minutes faster :D
Also able to come back 40 years later and STILL rev to 20,000. All in a small town square with the sound echoing around :drool:
But you are right compared to TODAYS 2-strokes they ate oil. The Honda ceramic engine solved that -- but unfortunatley blew up every time it raced :D

The super large diesel I am talking about can reach 50% thermal efficiency!
Good point, I was stuck thinking petrol. Two stroke diesel better for sure :)

Why is everybody still thinking about Stirlings and ceramic composites???
The Stirling is only going around because I picked the most ridiculous engine to operate a car with, but one with the capacity for the highest energy extraction.

A no-loss water injection system! inject water just as ignition is starting and most of the heat will be transformed into greater pressure, then you can have a lighter block and no radiators.
But you also create acidic compounds and cause emissions issues. Can't remember the mix but it's not easy to remove needing two stage catalytics IIRC. It became a dead end for the car makers.
( Mind you with modern injection and better CFD in cylinder design -- maybe .... hmm got me thinking there, ht, any links to anyone doing current development ?? )
[/quote](I hope everybody realises that it is not the heat but the pressure that makes things go round)[/quote]
I think so because we've all been talking about pressure :D





Thanks for the rest, th, I'm close to delivering a MetA "response" to Stian who isn't listening and in his response where he SAYS he isn't thinking about one thing at a time goes on to prove it. You words were kinder than I would have managed this time around.

stian -- you are wrong. The evidence has been presented. My parting comment to you .... learn about the difference between peak and average and you would understand the Stirling/Hybrid and realise the HUGE mistake :) The rest of it ?? .... listen to ht :D

hightower99
02-28-2006, 05:58 AM
But you also create acidic compounds and cause emissions issues. Can't remember the mix but it's not easy to remove needing two stage catalytics IIRC. It became a dead end for the car makers.
( Mind you with modern injection and better CFD in cylinder design -- maybe .... hmm got me thinking there, ht, any links to anyone doing current development ?? )
this is what happened in the past. I believe that with a synthetic oil and better ring seal technology (it exists it just has to be used) that oil and water can be kept seperate for the most part and that when they do meet that they do not produce nasty compounds. I don't know of anyone looking into it right now, but I plan to try some test systems out on a turbo diesel. (When I turn the key what will happen?)

also I am talking about water injection as an entire cooling system not a intercooler or whatever.

also a good note that with water injection cooling with a no-loss system (as in you don't need to keep filling up on water) then efficiency can be raised very high as it is theretically possible to have exaust temperatures that are lower than intake after turbocharging temperatures. (a theretical but believeable example would be exaust temp of 20deg C and a intake after turbocharging temp of 300deg ((no intercooler)))

stian1979
02-28-2006, 07:01 AM
What??? I don't think so they guzzeled gas and oil like crazy for thier power output! The super large diesel I am talking about can reach 50% thermal efficiency!

They are actualy betwen 50-55% nowdays.




Water injection prove to giwe lover emisions but only 5-15% will give a power increase since more than that only will cool down the gasses to mutch and you will not have a power loss instead. Heat don't make things go around? Do you know that if air dubble it's temperature it will grow to 5 times the volum? This means that preshure will increase if the air has nowhere ti exspand.

[QUOTE=hightower99]
about the revetec vibrating too much, stian1979: the revetec can be made so that the pistons move just like in a normal boxer! (without all the side loading of course!)

Yes it can, but now it's geting more heavy again :(



A good engine will combust more than 80% of the fuel in the cylinder before 20 deg ATDC the remaining power from the remaining gas is not enough to keep the pressure high through the expansion phase!(in other words the remaining gas doesn't add any power it simply slows the loss) Most conventional crank engines reach maxium conversion efficiency at around 60deg not 90deg like you think they do.

Diesel don't and this will probartly be the engine that will be more and more dominat because it don't bother that mutch about fuel qualety. You can runn it on LNG or asfalt(if you heat it up to 170C) Why do you thing big diesels at 10MW ++ has long stroke? Lots of rasons, but one of the is that it gets time to burn things that normal engines would not be able to combust.


this is about as missled as I care to read. the 30% efficiency you are talking about in a normal engine is the thermal energy. (as in theretical total energy of fuel used divided by the output energy) the revetec is 3 times more mechanically efficient not thermally! you are relating numbers and doing top of the head math that shouldn't be! Both the revetec and a normal engine have the same amount of waste heat!

Yeah right. I would like to see a engine provide "3" times the torque at the same fuel consumption, same outer crank diameter and same heat loss. If they say a 5% or even 20% Increase due to bether transfere of forces I could buy it, but 3 times no. Sorry hightower.Scotch Yoke kan do the same just as good.


stian -- you are wrong. The evidence has been presented. My parting comment to you .... learn about the difference between peak and average and you would understand the Stirling/Hybrid and realise the HUGE mistake :) The rest of it ?? .... listen to ht :D

I know about all this mathers so I dear to say you are wrong. You have ben reading to mutch on revetec.com and svoloved the bait with the hock, line and maybe even the fisher. Try to make this engine yourself and runn it in MSC Adams. You still think your the tecnical Albert Einstein so why are no one running Hybrid Stirlings now? Do you belive in conspiracy to keep oil consumtion up and oil price up? If Stirling was so perfect as you try to make it seam every one would have a stirling hybrid in there model programe now.

If your only going to start it up and drive normaly to work it will probartly work just fine, but if you got to brake down to a dear crosing the road after only 30 secs of driving and then acelerate again the stirling would stil strugle to take load and the batterys would be empthy. It's not every day driving My consern is, but things that hapend that you did not exspect in the first place. This could be solved by using the electric motor as a generator to brake the weel's and runn the power to bateries by excitation of the motors, but now costs and system compeksety rise.

So strange the car industri don't jump on to your ideas of perfect engines and sulutions if they are so great.:D


this is what happened in the past. I believe that with a synthetic oil and better ring seal technology (it exists it just has to be used) that oil and water can be kept seperate for the most part and that when they do meet that they do not produce nasty compounds. I don't know of anyone looking into it right now, but I plan to try some test systems out on a turbo diesel. (When I turn the key what will happen?)

also I am talking about water injection as an entire cooling system not a intercooler or whatever.

also a good note that with water injection cooling with a no-loss system (as in you don't need to keep filling up on water) then efficiency can be raised very high as it is theretically possible to have exaust temperatures that are lower than intake after turbocharging temperatures. (a theretical but believeable example would be exaust temp of 20deg C and a intake after turbocharging temp of 300deg ((no intercooler)))

Like I say befour in this post it's limited how mutch you can spray in of water. If you increase preshure water will avaporate at a higher temperature. 60bar preshure is enough to keep water from not boiling even at 200C++

Also it has some other effects. H2O+Fe=? and heat make it go faster. And if it get out of the cylinder into the engine you have something called hydrocarbons or oil. H2O + hydro carbons can make organic acid's and I would not like that in my engine. Ceramics are interesting. No cooling neaded and you can wrap in the engine with insulation and water will not be a ishue if cylinder components are made from material that don't rust.

stian1979
02-28-2006, 08:29 AM
http://www.autoblog.com/2005/12/09/bmw-turbosteamer-gets-hot-and-goes/ some one got there eyes up for the future as I see it. Heat recovery.

Matra et Alpine
02-28-2006, 09:17 AM
oil and water can be kept seperate for the most part and that when they do meet that they do not produce nasty compounds.
I was meaning IN the combusino chamber and the mix of air and fuel.
Partial combustion generates acid compunds rahtehr than free gasses. So when it gets to teh catalyst, furirst it's done dmamge on teh way and second the catalyst has to first break down the acid and THEN combine to stabilise.

also I am talking about water injection as an entire cooling system not a intercooler or whatever.
A given, intercooling and charge cooling are well undestood and used.

also a good note that with water injection cooling with a no-loss system
Ohhh, wasn't thinking zero-loss :D
So how do you recover the water ?
Especially as some of it WILL have combined to form acid compounds.
How much energy does it take to keep a cold surface condensor cold ??

Matra et Alpine
02-28-2006, 09:19 AM
http://www.autoblog.com/2005/12/09/bmw-turbosteamer-gets-hot-and-goes/ some one got there eyes up for the future as I see it. Heat recovery.
We discuss ed this one before.
Difficult to see how much it really benefits given teh extra weight it's carryign around :(
Seemed like it really would need triple expansion to recover more to warrant the weight. ( My subconscious has worked on that to and it woudln't work as it's NOT high pressure so the last piston would need to be the size of a large bucket :) )

drakkie
02-28-2006, 12:41 PM
to reply partly off-topic:

The gains of the CVT in the DAF f3 (or was it an f2 car ?) car were around and about 34-36 percent.On certain tracks even as high as 45-50% !!! No shifting time meant a huge advantage. DAF was planning more racing and sports activities to approve their image (especially in holland) before the passenger vehicle part of the company went bust and these racing activities were also cancelled. The CVT was used in the f3/f2 cars cos of the low amount of power. at the time a max. of 250 hp was there :( There are cvt's used in (experimental) trucks which have power up to 1000-1500 hp :D

Matra et Alpine
02-28-2006, 12:50 PM
to reply partly off-topic:

The gains of the CVT in the DAF f3 (or was it an f2 car ?) car were around and about 34-36 percent.On certain tracks even as high as 45-50% !!! No shifting time meant a huge advantage.
Not really.
www.f3history.co.uk/Manufacturers/DAF/daf.htm (http://www.f3history.co.uk/Manufacturers/DAF/daf.htm)

http://www.f3history.co.uk/Manufacturers/DAF/images/daf1.jpg

DAF was planning more racing and sports activities to approve their image (especially in holland) before the passenger vehicle part of the company went bust and these racing activities were also cancelled.
The racing was cancelled LONG before DAF went bust.

The CVT was used in the f3/f2 cars cos of the low amount of power. at the time a max. of 250 hp was there :( There are cvt's used in (experimental) trucks which have power up to 1000-1500 hp :D
Yeah but those dont' use belts (or they didnt' used to ) and so the losses in the transmission are quite high. Big and heavy too. Not an issue in a truck :D
Got any links for the progress on the experiments as it' skind of gone quiet :(

KnifeEdge_2K1
02-28-2006, 01:37 PM
hly crap they need a special nerd section on this forum just for u 3 ...

Matra et Alpine
02-28-2006, 02:02 PM
hly crap they need a special nerd section on this forum just for u 3 ...
Why ?

is it not better that everyoen gets the chance to learn more ?

Or are you only happy if we're talking about how much faster the car goes from STIKKAS :)

hightower99
02-28-2006, 02:22 PM
Water injection prove to giwe lover emisions but only 5-15% will give a power increase since more than that only will cool down the gasses to mutch and you will not have a power loss instead. Heat don't make things go around? Do you know that if air dubble it's temperature it will grow to 5 times the volum? This means that preshure will increase if the air has nowhere ti exspand. HAHAHAHAHA! the highlighted part shows that you know nothing of physics, have you ever heard of Boyle's Law? it says that if you double the temperature of a gas then the volume of that gas will double in size (It will not expand by 5!)

the power generated by the water injection (Which I believe would work better if indirectly injected) happens when you inject enough water, so that the temperature is halved when the water turns to dry steam. the volume of the air will fall by half but the water will have expanded by more than 1600 times. So if you inject 1cubic centimeter of water dispersed throughout the cylinder as a fine mist, and the cylinder has a max volume of 500ccs then the water will create over 1600ccs of steam. Now lets say that the water is turned to steam when the piston is down far enough to have 100cc in it. the steam alone would give a pressure of 16 bar but it is with all the other gasses making the increase in pressure slightly more. So in the end you are looking at around 300 extra pounds of force per square inch and on a piston with 10 square inches (a small bore motor) then you are looking at 3000lbs. of extra force! that is more than alittle bit!


Yes it can, but now it's geting more heavy again
no it doesn't my design makes it even lighter!!!


Diesel don't and this will probartly be the engine that will be more and more dominat because it don't bother that mutch about fuel qualety. You can runn it on LNG or asfalt(if you heat it up to 170C) Why do you thing big diesels at 10MW ++ has long stroke? Lots of rasons, but one of the is that it gets time to burn things that normal engines would not be able to combust.
Actually diesels will be more and more popular because the fuel is cheaper and because they get better mileage and because you can tune them easier and because they can run on biodiesel (which is easier to make than bio gas) I will bet you that no car will have a diesel that runs on asphalt (because you can make about 30L of diesel out of 1L of asphalt!) and actually diesels due burn about 80% of the fuel before 20deg ATDC!


Yeah right. I would like to see a engine provide "3" times the torque at the same fuel consumption, same outer crank diameter and same heat loss. If they say a 5% or even 20% Increase due to bether transfere of forces I could buy it, but 3 times no. Sorry hightower.Scotch Yoke kan do the same just as good.

first there is not the same outer crank diameter (it starts out more than a normal engine of the same stroke and goes down) and there is a slightly lower in cylinder heat loss (higher average pressure firing due to short stroke) even so you have no reason to doubt the claims because if you look at a crankshaft it only ever reaches 95% conversion efficiency and only for a fraction of the full power stroke (the calculated average is 30% for most square engines) the revetec is constantly at 80-90% efficiency but the average is about 90% for the whole power stroke!... 90/30=3... yeah!

oh and the scoth yoke sucks to much friction and too heavy (as opposed to what the websites want you to think!)

Matra et Alpine
02-28-2006, 02:36 PM
oh and the scoth yoke sucks to much friction and too heavy (as opposed to what the websites want you to think!)
Still pretty good for the 50s tho' :D
With modern lighter strogner materials and better lubricants has anyone done any recent work on it.

For example for the Ford "traction drive" CVT they had mating surfaces between two rotating cones. The lubricant for IT was capable of preventing metal to metal contact at pressures up to 600,000 pounds per square inch against each other. ( Dont know how good an actual "lubricant" it was though as the purpose was to "stick" rather than "slide".

stian1979
02-28-2006, 09:04 PM
HAHAHAHAHA! the highlighted part shows that you know nothing of physics, have you ever heard of Boyle's Law? it says that if you double the temperature of a gas then the volume of that gas will double in size (It will not expand by 5!)

Oppsss. you just show you know nothing at all :D That depends on the gas my frien and I man enough to admit I'm wrong. Oxygen has a coefficient of (thermal) expansion at 4,86, but air has only 3,67 x 10^-3 K^-1


the power generated by the water injection (Which I believe would work better if indirectly injected) happens when you inject enough water, so that the temperature is halved when the water turns to dry steam. the volume of the air will fall by half but the water will have expanded by more than 1600 times. So if you inject 1cubic centimeter of water dispersed throughout the cylinder as a fine mist, and the cylinder has a max volume of 500ccs then the water will create over 1600ccs of steam. Now lets say that the water is turned to steam when the piston is down far enough to have 100cc in it. the steam alone would give a pressure of 16 bar but it is with all the other gasses making the increase in pressure slightly more. So in the end you are looking at around 300 extra pounds of force per square inch and on a piston with 10 square inches (a small bore motor) then you are looking at 3000lbs. of extra force! that is more than alittle bit!


This is a fact with modifications. How manny times the water will exspand depends on preshure and temperature. If the preshure is 22090kPa the water would not exspand at all and if it's at 1kPa it will exspand 120000 times.



no it doesn't my design makes it even lighter!!!
I don't belive you unless it's not a revetec annymore. Please make me



Actually diesels will be more and more popular because the fuel is cheaper and because they get better mileage and because you can tune them easier and because they can run on biodiesel (which is easier to make than bio gas) I will bet you that no car will have a diesel that runs on asphalt (because you can make about 30L of diesel out of 1L of asphalt!) and actually diesels due burn about 80% of the fuel before 20deg ATDC!
I will not bet you on that, but there are diesels running on asfalt.
Large stroke ship's like you mention yourself befour.




first there is not the same outer crank diameter (it starts out more than a normal engine of the same stroke and goes down) and there is a slightly lower in cylinder heat loss (higher average pressure firing due to short stroke) even so you have no reason to doubt the claims because if you look at a crankshaft it only ever reaches 95% conversion efficiency and only for a fraction of the full power stroke (the calculated average is 30% for most square engines) the revetec is constantly at 80-90% efficiency but the average is about 90% for the whole power stroke!... 90/30=3... yeah!

OK! What ever make you happy, but I would not have a revetec even if you dip it in honey and roll it in marzipan.


oh and the scoth yoke sucks to much friction and too heavy (as opposed to what the websites want you to think!)

and the revetec don't? :D

Giwe me your e-mail so I can write you a long lether for apology the day I buy my first revetec powered car.


Still pretty good for the 50s tho' :D
With modern lighter strogner materials and better lubricants has anyone done any recent work on it.


Actualy I think it more from the the 1890-1910 area.

hightower99
03-01-2006, 01:41 AM
That depends on the gas my frien and I man enough to admit I'm wrong. Oxygen has a coefficient of (thermal) expansion at 4,86, but air has only 3,67 x 10^-3 K^-1
Wow you are a very confused person if I have 1 cubic centimeter of any gas and double the temperature then the gas will now fill 2 cubic centimeters! (think about it!) ((note that it is only a doubling of the absolute temperature that this happens))


This is a fact with modifications. How manny times the water will exspand depends on preshure and temperature. If the preshure is 22090kPa the water would not exspand at all and if it's at 1kPa it will exspand 120000 times.umm you do realise that I am talking about when water (a liquid) turns into dry steam (a gas) I assure you that water does turn to steam when injected into an engine and that the calculated value of expansion between water at it's densist (4deg C) and totally dry steam (100deg C) is over 1600 times. If you increase the temperature of the gas even more than it expands accordingly! ((in a confined container pressure goes up))


I don't belive you unless it's not a revetec annymore. Please make me My design is based on revetec insomuch as it still uses a counter-rotating cam system to convert linier motion into rotary motion. And I would rather you didn't believe in my design as that intolls faith and I have no need of faith!


I will not bet you on that, but there are diesels running on asfalt.
Large stroke ship's like you mention yourself befour.
Do you read my posts or what?!? I know that large ships run on warmed asphalt and other heavy oils they do so because it is super cheap! You will never have a car that runs on asphalt and therefore you previous statement is irrelevant!


and the revetec don't?

Giwe me your e-mail so I can write you a long lether for apology the day I buy my first revetec powered car.
the revetec system is relatively light weight and is much lower friction than a conventional crank design and the convensional crank design is much better than the yoke so...!

and I am not about to hand out my email to some yaahoo on a net forum cause all that will get me is a pathetic attemp to spam me!


Actualy I think it more from the the 1890-1910 area.EXACTLY do you realise that the normal crankshaft design that is in most ICEs right now was invented to replace the Yoke! the scotch yoke was dated back in 1910!

stian1979
03-01-2006, 06:53 PM
Wow you are a very confused person if I have 1 cubic centimeter of any gas and double the temperature then the gas will now fill 2 cubic centimeters! (think about it!) ((note that it is only a doubling of the absolute temperature that this happens))

OK! so you don't belive in coefficient of (thermal) expansion? so nice, in your world a steel pipe wont grow longer if heated.


umm you do realise that I am talking about when water (a liquid) turns into dry steam (a gas) I assure you that water does turn to steam when injected into an engine and that the calculated value of expansion between water at it's densist (4deg C) and totally dry steam (100deg C) is over 1600 times. If you increase the temperature of the gas even more than it expands accordingly! ((in a confined container pressure goes up))

Now your talking about a preshure betwen 100-110kPa. My cylinder preshure is way higher than that. 100kPa is normal atmospheric pressure. This means that at a preshure of 18bara you will only get 92 times ekspension and this is only a compresion preshure. How high will it go durning combustuon? The ekspansion you are talking about will only hapend when the exhaust valve open.


My design is based on revetec insomuch as it still uses a counter-rotating cam system to convert linier motion into rotary motion. And I would rather you didn't believe in my design as that intolls faith and I have no need of faith!

I recond this means no profe.



Do you read my posts or what?!? I know that large ships run on warmed asphalt and other heavy oils they do so because it is super cheap! You will never have a car that runs on asphalt and therefore you previous statement is irrelevant!

I read your post twice as good as you read mine. I staded that diesels are the future because it can burn annything as long as it is a liquid and has calorific value.


the revetec system is relatively light weight and is much lower friction than a conventional crank design and the convensional crank design is much better than the yoke so...!

I simply don't belive it has lover friction because off it's contrarotating mecanism. The ball bearing's is something that will nead replacement often and plain bearings can't be adopted.


and I am not about to hand out my email to some yaahoo on a net forum cause all that will get me is a pathetic attemp to spam me!

On yourown actions you know others. Now I know what you would do.


EXACTLY do you realise that the normal crankshaft design that is in most ICEs right now was invented to replace the Yoke! the scotch yoke was dated back in 1910!

So the normal crankshaft was invented after the Yoke? at 1910?
WOW. I have seen normal crankshaft engines fom 1906 in the Wickmann museum. Well at least you make me laugh.

The advantages compared to a standard crankshaft and connecting rod setup are:
High torque output with a small cylinder size.
Fewer moving parts.
Smoother operation.
Higher percentage of the time spent at top-dead-center and bottom-dead-center (dwell) improving engine efficiency.

The disadvantages are:
Rapid wear of the slot in the yoke.

This setup is most commonly used in control valve actuators in high pressure oil and gas pipelines.

See the Yoke is in sucsesful use http://www.scana.no/no/ssr/news-and-media/nedlasting

Don't you even find it alarming that revetec hide so mutch information on there web page? If they have the patents nobody can steal it from them annyway.

I got a nice bock for you ISBN-82-00-42450-2 maybe they have it in English to.

Cyco
03-02-2006, 04:19 AM
Don't you even find it alarming that revetec hide so mutch information on there web page? If they have the patents nobody can steal it from them annyway.

Just because you have a patent to protect your idea doesnt't mean you have any protection if you don't have the money to fight it in court.

hightower99
03-02-2006, 04:28 AM
OK! so you don't belive in coefficient of (thermal) expansion? so nice, in your world a steel pipe wont grow longer if heated.
Yes I do believe in coefficient of expansion (READ the post don't skim it!). Metals do expand when there temperature is raised but they do not follow the same rules as gasses (as in a rod of steel doesn't double it's volume if I double the absolute temperature) so gasses change there size, liquids change there size, and even solids change there size!


Now your talking about a preshure betwen 100-110kPa. My cylinder preshure is way higher than that. 100kPa is normal atmospheric pressure. This means that at a preshure of 18bara you will only get 92 times ekspension and this is only a compresion preshure. How high will it go durning combustuon? The ekspansion you are talking about will only hapend when the exhaust valve open. sorry my last post (the part you quoted) has all the info there.


I recond this means no profe.
No it means I don't need your faith! and what do you mean no proof I have only drawn some drawings and done some very like math. I have not got my hands on a revetec engine yet so I couldn't give you a direct proof but I could give you some pictures... and let you make your own conclusions.


I read your post twice as good as you read mine. I staded that diesels are the future because it can burn annything as long as it is a liquid and has calorific value. Well just if it was alittle to unclear for you DEISELS ARE NOT AND WILL NOT BECOME SUPER POPULAR DUE TO THE FACT THAT THEY CAN BURN ALMOST ANYTHING THAT CAN BE ATOMISED AND HAS A CALORIC VALUE!!!!! the reasons for there increasing popularity has nothing to do with that it has to do with the things I stated. So next time READ my posts!


I simply don't belive it has lover friction because off it's contrarotating mecanism. The ball bearing's is something that will nead replacement often and plain bearings can't be adopted. Counter rotating= less vibration= less loss due to frictions and stresses! and ball bearings can last along time if they are correctly matched to the job (Like in the ball bearing turbos I see which have been used hard for 120000km!!!)


So the normal crankshaft was invented after the Yoke? at 1910?
WOW. I have seen normal crankshaft engines fom 1906 in the Wickmann museum. Well at least you make me laugh.

The advantages compared to a standard crankshaft and connecting rod setup are:
High torque output with a small cylinder size.
Fewer moving parts.
Smoother operation.
Higher percentage of the time spent at top-dead-center and bottom-dead-center (dwell) improving engine efficiency.

The disadvantages are:
Rapid wear of the slot in the yoke. Yes the scotch yoke came first or very very close to the crankshaft. The normal crankshaft wasn't invented in 1910 and I never said it was! I said that the scotch yoke was old tech by 1910!

the advantages you list are rediculess and they are not true
The crankshaft/connecting rod design gets better torque per smaller cylinder size (What ever that means?)
A scoth yoke needs 4 parts for a single piston while a normal setup needs only 3. So a normal setup has fewer parts.
smoother operation might be true due to less side loading.
And the last bit about more time at TDC and BDC is really funny cause that will not help an engine much especially in the future when they need to run on detonation mode! (You do know that a piston does no work at TDC and BDC so why should it be there for a longer amount of time?) Your listed disadvantage is only the most obvious one which is caused by a large amount of friction! it is most definately true!

Matra et Alpine
03-02-2006, 06:46 AM
Don't you even find it alarming that revetec hide so mutch information on there web page? If they have the patents nobody can steal it from them annyway.
If you ever manage to invent then do NOT make that mistake.

Every patent application is kep as secret as possible until it is made public.
This can be up to two years and in some cases is deliberately made longer by the patentee by adding additional claims.

BECAUSE ....... as soon as your patent goes public there are companies who will take that patent and work to identify uses not considered AND possible developmetn needs in teh future. These companies then VERY QUICKLY apply for patents for those features. Suddenly a patent holder fo the KEY design finds out that he can't actually develop the product because of these other patents and has to engage in trying to purchase those rights.

Patents which were intially set up to ensure sharing of techincal advances has now become a business in it's own right.

stian1979
03-02-2006, 11:17 PM
Yes I do believe in coefficient of expansion (READ the post don't skim it!). Metals do expand when there temperature is raised but they do not follow the same rules as gasses (as in a rod of steel doesn't double it's volume if I double the absolute temperature) so gasses change there size, liquids change there size, and even solids change there size!

So you realised that now?
Iron 11,7 x 10^-6 K^-1 (coefficient of expansion in lenght)
water 0,21 x 10^-3 K^-1 (coefficient of expansion in volum)
Air 3,67 x 10^-3 K^-1 (coefficient of expansion in volum)


Well just if it was alittle to unclear for you DEISELS ARE NOT AND WILL NOT BECOME SUPER POPULAR DUE TO THE FACT THAT THEY CAN BURN ALMOST ANYTHING THAT CAN BE ATOMISED AND HAS A CALORIC VALUE!!!!! the reasons for there increasing popularity has nothing to do with that it has to do with the things I stated. So next time READ my posts!

Read my post.
They are coming more populat for that reason. I did not say today smartass.
Once we will maybe not be able to alow our self runn on high grade fuel. Did you think about that? Gasoline is depended on octan and diesels are not.



Counter rotating= less vibration= less loss due to frictions and stresses! and ball bearings can last along time if they are correctly matched to the job (Like in the ball bearing turbos I see which have been used hard for 120000km!!!)

I think you are out of your leaf here. Torbo bearings are moustly plain bearing's. When they are fitted with ball bearings is moustly for high performance aplications. Torbos don't have huge loads on the bearings and the diameter is smal so the peripheral speed will not be high. Smal bearing=high speed.


Yes the scotch yoke came first or very very close to the crankshaft. The normal crankshaft wasn't invented in 1910 and I never said it was! I said that the scotch yoke was old tech by 1910!

pneuamtic scotch yoke actuators is produced in 100's all ower the world. All this manufacturers don't understand what you do?


the advantages you list are rediculess and they are not true
The crankshaft/connecting rod design gets better torque per smaller cylinder size (What ever that means?)
A scoth yoke needs 4 parts for a single piston while a normal setup needs only 3. So a normal setup has fewer parts.

And how manny parts dos the fantastic Revetec nead?


If you ever manage to invent then do NOT make that mistake.

Every patent application is kep as secret as possible until it is made public.
This can be up to two years and in some cases is deliberately made longer by the patentee by adding additional claims.

This Prototype named 96-5.3-01 (year-version-number) was first started up on the Queens Birthday 1996. WOW. the years in australia is long.

Patents on what by the way? Cams are invented, gear for contrarotating is invented and the pistion concept is invented. Used by Yoke befour.


BECAUSE ....... as soon as your patent goes public there are companies who will take that patent and work to identify uses not considered AND possible developmetn needs in teh future. These companies then VERY QUICKLY apply for patents for those features. Suddenly a patent holder fo the KEY design finds out that he can't actually develop the product because of these other patents and has to engage in trying to purchase those rights.

Patents which were intially set up to ensure sharing of techincal advances has now become a business in it's own right.

So it's not to late to late to apply the patent for usage off the weel yet?
WOW
I can get ritch.

If a engine produce 400Nm at 3000RPM and is converted to a revetec design and then produce 3 times the torque.

Now that means the revetec design should produce 3 times the power too.
Nm x RPM is kw.
kW=Nm/s or kJ/s.

Revetec say they produce 3 times the torque, but the same power?
I find that sounding like a back yard mecanic from Texas.

Sorry guys
I don't buy it.

The two of you can discus advantages about the revetec because I don't care to point out the montain off lies and disadvantages to the two of you.
Good luck.

teatako
03-03-2006, 11:04 PM
i want one of these for my smart roadster

Matra et Alpine
03-08-2006, 03:54 AM
This Prototype named 96-5.3-01 (year-version-number) was first started up on the Queens Birthday 1996. WOW. the years in australia is long.
Please go back and read wher I pointed out that a clever patentee will add additional claims on an on-going basis forcing the patent BACK into application state and not requiring publishing !!
MANY years. One of mine was filed in 2001, the compamy keeps adding a few things and it MAY get published next year ( we're running out of new ideas around the basic concept :) )

Patents on what by the way? Cams are invented, gear for contrarotating is invented and the pistion concept is invented. Used by Yoke befour.
HOW you use something is patentable even if the thing was patented before.
How you use a feature to deliver some NEW capability - additional power or efficiency is also patentable. So I can apply for a patent to use a micro revetec engine (say) to power a next generation laptop :D The engine existed, the laptop existed, my patenn would be for the application !! Anyone writing a patent themself tries to cover ALL those eventualities before it is published. Again, if you go back to what I said earlier post abotu patents then you will understand better.

So it's not to late to late to apply the patent for usage off the weel yet?
WOW
THAT is a correct statement IF you ahve some new applicaiton of the wheel. If you can find a way to use a wheel to cure cancer then you can patent it. You can't manage to patent it to move a vehicle :) ( Interestingly in nano technology there are patent filings abotu nano-hweels, motors etc )

I can get ritch.
only if you are smart enough to INVENT, smart enough to write a cast iron patent for a valuable application AND smart enough to spell :)

If a engine produce 400Nm at 3000RPM and is converted to a revetec design and then produce 3 times the torque..........................Revetec say they produce 3 times the torque, but the same power?
I find that sounding like a back yard mecanic from Texas.
You sir don't understand engines :)
On YOUR assumption then a long stroke engine with higher torque output should ALSO produce higher power than the same engine with shorter stroke/larger bore .... PS: They dont :)

Sorry guys
I don't buy it.
That's OK, we're not asking you to.
Pearls before swine :D

PBB
03-08-2006, 09:56 AM
the power generated by the water injection (Which I believe would work better if indirectly injected) happens when you inject enough water, so that the temperature is halved when the water turns to dry steam. the volume of the air will fall by half but the water will have expanded by more than 1600 times. So if you inject 1cubic centimeter of water dispersed throughout the cylinder as a fine mist, and the cylinder has a max volume of 500ccs then the water will create over 1600ccs of steam. Now lets say that the water is turned to steam when the piston is down far enough to have 100cc in it. the steam alone would give a pressure of 16 bar but it is with all the other gasses making the increase in pressure slightly more. So in the end you are looking at around 300 extra pounds of force per square inch and on a piston with 10 square inches (a small bore motor) then you are looking at 3000lbs. of extra force! that is more than alittle bit!
Hightower, you're always good for a chuckle.
Water injection does not create power by vaporizing into steam.

Water injection indirectly creates power by removing heat from the combustion chamber via steam vaporization. This lowering of the cylinder temperature raises the detonation threshold which allows the engine tuner to make more power by 1) leaning out the air/fuel mixture 2) advancing the timing 3) raising the boost 4) use lower octane fuel to make the same power as an engine on high-octane fuel without water injection. Raising the boost yields, by far, the biggest power gains which is why water injection is used primarily on forced induction engines.

While your grasp of physics and their theoretical application is exemplary for a 17 year old, you still fail hardcore at many practical apects of engine design and tuning.

hightower99
03-09-2006, 12:31 AM
Hightower, you're always good for a chuckle.
Water injection does not create power by vaporizing into steam.

Water injection indirectly creates power by removing heat from the combustion chamber via steam vaporization. This lowering of the cylinder temperature raises the detonation threshold which allows the engine tuner to make more power by 1) leaning out the air/fuel mixture 2) advancing the timing 3) raising the boost 4) use lower octane fuel to make the same power as an engine on high-octane fuel without water injection. Raising the boost yields, by far, the biggest power gains which is why water injection is used primarily on forced induction engines.

While your grasp of physics and their theoretical application is exemplary for a 17 year old, you still fail hardcore at many practical apects of engine design and tuning.

Well You quote what water injection does now. Water injection is only a indirect power adder as of now but if you used it as a cooling system and got rid of the radiator like I said. You could take advantage of all the things you mention as well as increased pressure from the added mass! also a decrease in weight due to no radiators.

Matra et Alpine
03-09-2006, 03:57 AM
Well You quote what water injection does now. Water injection is only a indirect power adder as of now but if you used it as a cooling system and got rid of the radiator like I said. You could take advantage of all the things you mention as well as increased pressure from the added mass! also a decrease in weight due to no radiators.
hmmm, for that to work I think you woudl need MASSIVE compression as if you do not the initial creation of super heated steam will actually prevent the on-going wave front of the combustino gasses.
I'll do the math with my BP petrochemicals friend tonight over a beer -- so no guarantees of accuracy :D

PBB
03-09-2006, 12:39 PM
Well You quote what water injection does now. Water injection is only a indirect power adder as of now but if you used it as a cooling system and got rid of the radiator like I said. You could take advantage of all the things you mention as well as increased pressure from the added mass! also a decrease in weight due to no radiators.
Use. water. injection. to. replace. the. radiator. ?.

*chuckle* Well, let us know how that works for ya.

Blitz_
03-09-2006, 10:07 PM
fark, ok this is one helluva convo, ive just read page 1 through to 7, and possibly 30% of the terminology and concepts i understand. Matra ya bastard, i envy your intelligence and understanding of cars :D

Btw, back on topic (well the thread title) It's an interesting concept that I hope comes into at least (small) production to show the world its potential and further development if it were provided with more funding. There is always room for improvement in an engine, and simply bagging it in current stage wouldn't be justifiable if there are already plans for improvements with fuel efficiency and what not.

KnifeEdge_2K1
03-11-2006, 01:34 AM
who said use water cooling to replace radiator ??water cooling will cool the intake charge, it doesnt remove heat from the block and engine parts

KnifeEdge_2K1
03-11-2006, 01:36 AM
development in current combustion powered engines i think is a stupid concept, we're gonna run outta fossil fuels soon, thus it wont warrant more development into something we wont be able to use into the forseable future, better invest in hydrogen power, and electric cars which can last longer then an ipod and without battery problems

hightower99
03-13-2006, 06:27 AM
who said use water cooling to replace radiator ??water cooling will cool the intake charge, it doesnt remove heat from the block and engine parts it doesn't in current applications but I suggested that it is possible and that it would help!


development in current combustion powered engines i think is a stupid concept, we're gonna run outta fossil fuels soon, thus it wont warrant more development into something we wont be able to use into the forseable future, better invest in hydrogen power, and electric cars which can last longer then an ipod and without battery problems we are not going to run out of fossil fuels soon (unless you consider 75-100 years soon?) and even when we due no other form of engine can beat ICEs for the energy concentration!!! Developments in ICE technology is what is going to make things better. Diesels will become the most popular engines because they can run cheaply on totally organic fuel (renewable) and then there is always metal nano dust (reuseable) and hydrogen (renewable)... Electric cars are great for in-city non poluting transport but to fly jets and drive any sort of equipment long distances you are going to need an ICE!

derekthetree
03-13-2006, 07:00 AM
we are not going to run out of fossil fuels soon (unless you consider 75-100 years soon?)

depends if you want to run your car on coal or not :)

there are very few untapped oil fields left and there aren't any new ones being made anytime soon

hightower99
03-13-2006, 12:38 PM
depends if you want to run your car on coal or not :)

there are very few untapped oil fields left and there aren't any new ones being made anytime soon

75-100 years is when the crude oil supply will be too small and expensive to get to be profitable...

derekthetree
03-13-2006, 01:59 PM
75-100 years is when the crude oil supply will be too small and expensive to get to be profitable...

sounds like an extreme upper bound to me...

hightower99
03-14-2006, 01:30 AM
sounds like an extreme upper bound to me...

not really there is 25 years there.... Everyone has atleast 75 years of motoring left before everything stops and it could go on for another 25 years after that... but even after 100 years there will still be fuels for use in ICEs

KnifeEdge_2K1
03-15-2006, 03:36 PM
under current consumption patterns and rates this estimate MAY be true, but developing countries are increasing their ussage of fossil fuels and such to maintain/increase this growth, as a result of getting richer they'll also buy cars
you could argue that cars are becoming more efficient but imho i dont think that they'll become mainstream quick enough to do any measurable good

all of this is besides the point since we know that the supply of fossil fuels wont last forever so why not get an early start on an alternative hopefully renewable and non poluting fuel ??

Egg Nog
03-15-2006, 09:32 PM
who said use water cooling to replace radiator ??water cooling will cool the intake charge, it doesnt remove heat from the block and engine parts

It is physically impossibly for the water not to remove heat from the block and engine parts. Especially since water has such a massive specific heat capacity, it's quite a substantial amount of cooling in the case of water injection.


Use. water. injection. to. replace. the. radiator. ?.

*chuckle* Well, let us know how that works for ya.

You guys are very quick to assume. The fact that you've never heard of it has little to do with the possibility of it being a viable idea. It's not just a good idea either - it actually exists.

Bruce Crower (I'm sure you've heard of Crower internals) has invented a highly efficient single cylinder 6-stroke gas/steam engine. Not only does the water injection/steam help make the fuel last longer, but it helps in the cooling process as well. The engine doesn't require a radiator.

pneumatic
09-15-2006, 05:14 AM
I just read this whole page from 1 to 7, and can't believe what I am reading. stian1979 is the only person here that understands what's happening here.

The revetec engine is equivalent to a conventional engine with a 3:1 reduction built in to it. If it's output shaft is doing 3,000rpm, then it's camshafts, valvetrain, and pistons are doing an effective 9,000rpm.

Therefore it looks impressive to the untrained eye.

If you don't believe the 3:1 thing, then just look at it.

On a normal engine the crank runs the camshafts at a ratio of 1:2. If you have 10 teeth on your crank pulley, you have 20 teeth on your crank pulley.

Because the revetec is a 3-lobe design, it is like having the output shaft (crank) geared down 3:1. So you need to gear the drive to the cams back up 3:1 to get the same piston and cam cycle ratio. So you basically need to have 3 x the normal 1:2 ratio. Or a ratio of 3:2. So if the crank pulley has 30 teeth, then the camshaft pulleys will have 20 teeth. Quite the opposite to the normal engine, and look, it does!!!

http://www.revetec.com/files/_images/DSC_0004.preview.jpg

pneumatic
09-15-2006, 05:39 AM
So what does the 3:1 ratio mean? It means they are cheating in some of their marketing.

Take their latest engine test results;
http://www.revetec.com/files/Announcement%20-%2004.05.06.pdf

The engine they specify is 1.38L. 94mm bore with 50mm stroke. That bore and stroke on a conventional engine gives 1.38L, so they are not compensating for the 3:1 ratio in their effective volume calculation.

So they have tested the engine and get 57kW@4,120rpm. With the effective 3:1 reduction taking into account it is really doing 57kW@12,360rpm.

And they get 140Nm@3,650rpm. But because of the 3:1 ratio they are really getting an effective 47Nm@10,950rpm, and then gearing it down so it looks more impressive. It's false advertising really.

And those effective rpms are correct, because that is what the piston speeds and valve train speeds are equivalent to.

Now they compare their relatively high performance engine (Haltech injection, custom made everything, probably individual throttle bodies) to a low performance production toyota engine. That's not very fair. They then say "Not only are we producing the same power with a smaller capacity engine, but we are doing it at a lower rev which saves fuel. We also are producing more torque than the Prius at a lower rev with a far shorter stroke."

Lower rev so it saves fuel? what a crock. That is so misleading. Because the revetec pistons go up and down 3 times as much, it will induce 3 times as much air into the engine, and therefore use 3 times as much fuel for any given rpm.

But why not compare the revetec 1.38L engine to a conventional engine in a similar state of tune? One that revs to around 12,000rpm?

Well that would be something like the Kawasaki ZX-14 engine. It is 1.35L, it makes about 140kW @ 10,000rpm, and about 160Nm at about 8,000rpm.

These figures absolutely embarrass the revetec motor. There is no comparison at all!!!

Or the other way to look at it is to compare a ZX-14 running through a 3:1 reduction box, and the revetec.

So the ZX-14 would now be 140kW @ 3,333rpm, and 480Nm @ 2,666rpm.
Compared to 57kW @ 4,120rpm and 140Nm @ 3,650rpm.

Can you people see the difference now???

That shows the revetc is working harder than the ZX-14 engine, and making way way less power and torque!

clutch-monkey
09-15-2006, 05:43 AM
That shows the revetc is working harder than the ZX-14 engine, and making way way less power and torque!
so basically it's competitive against similar sized car engines but redundant because bike engines do the same thing but much better?

pneumatic
09-15-2006, 06:08 AM
So the question becomes, why are the power and torque figures from the revetec so crap?

I'm guessing the horrible mechanical inefficiencies of the design.

One problem is the balancing as you've already been told but won't listen to. The opposing pistons are tied together. They move as one in the same direction, so will make horrible vibrations.

And people that say a conventional boxer engine is perfectly balanced is on drugs. Their cylinders do not directly oppose, they are offset. So they don't balance each other.

And people say it's a simple design??? It's got more parts than a conventional engine. Look below;
http://www.revetec.com/files/_images/DSC_0195.preview.jpg

The shaft through the center is the output shaft. The first and last tri-lobe is fixed to the output shaft, and so is the helical gear on the end (on the left in the pic).

The center gear is connected to another shaft, which is a sleeved outer shaft that fits over the inner main output shaft. But it isn't even a direct connection, there is planetary gears hiding in the middle there. This is because the gear on the left drives the shaft down the bottom, which then drives the gear in the center. But you want the inner two lobes (which are connected to the inner planetary gears and therefore center gear) to be going the opposite way to the outer lobes. So the planetaries are required to reverse that rotation direction. You might need to think about this a bit to understand.

So in order to get the crank mechanism to work, you need two big gears, two little gears, and an unspecified number of planetary gears. This is rather complex, and I am sure quite inefficient from a friction loss point of view. This is sure a lot more complicated than a conventional engine which has only a crankshaft and a conrod to do the same thing.

pneumatic
09-15-2006, 06:09 AM
so basically it's competitive against similar sized car engines but redundant because bike engines do the same thing but much better?

No, it's not competitive against similar sized car engines, because it has to work 3 times harder to do the same thing, and use 3 times as much air, and therefore 3 times as much fuel.

fpv_gtho
09-15-2006, 06:33 AM
Why does your argument sound like its coming from an industrial competitor?

pneumatic
09-15-2006, 06:50 AM
oh, and if you look at this;
http://www.revetec.com/files/_images/DSC_0004.preview.jpg

and then look at this;
http://www.vanbran.com/bug/images/conversion1/engine3_l.jpg

Now I am sure there are better pics out there, but that shows that the revetec engine is in fact running Subaru EJ20 / EJ25 cylinder heads, complete with factory oil filler.

So their 1.38L engine is running cylinder heads from a 2L conventional engine, but is supposed to be much smaller than conventional engines??? Doesn't look like it from that picture.

pneumatic
09-15-2006, 06:54 AM
I'm by no means an industrial competitor.

I did however write this spreadsheet;
http://autos.groups.yahoo.com/group/exceldyno/

and therefore am probably more qualified than most to talk about torque, horsepower, rpm and the effects on acceleration.

kigango123
09-15-2006, 02:07 PM
there have been so many concepts, quasiturbine, carnot cycle engines even the wankel this is just another trial and a poor one i might add

with this engine, the size or the surface area or volume to area ratio is inadequate, that means the engine will be heating the atmosphere not expanding
and what is this about increasing rpm to produce more power, sure it is done in f1 but it is extremely difficult to produce the same result in real life despite engine size, cbr motor at 600cc goes to 16,000 rpm, thats the best i have seen. this engine is better of being used as an oil pump or a personal vibrator rather than the current use

pneumatic
09-15-2006, 04:48 PM
Now they compare their relatively high performance engine (Haltech injection, custom made everything, probably individual throttle bodies) to a low performance production toyota engine.

I'll correct myself here, as I found the video of their 57kW 1.38L engine. It's not only using the 2-2.5L Subaru heads, it's also using the subaru intake manifold!

http://www.revetec.com/files/_images/rhl4web.jpg

So that means their 1.38L is as wide as a 2L subaru motor.

The revetec is probably as tall as the subaru, maybe taller because they need the balance shaft below. The only space saving they could make is maybe in engine length, as they don't need to offset the cylinders like in a traditional boxer motor, but then they need the big gear on the back so it increases the length again anyway.

But then it gets stranger. You see the subaru intake is offset, for the offset cylinders. And the cylinder head cam gear is offset for the same reason. They appear to be using the offset intake and cylinder head drives, then they also must have offset pistons. So at the moment their prototype doesn't have directly opposing pistons, and therefore cannot be any shorter than the subaru motor anyway! In fact with the big gear in the way their motor must be longer.

Below is a pic from an EJ20T which I think they are probably using the manifold and head from. You'll notice revetec are just using the intake bolted on backwards to the throttle body sticks out the opposite end of the engine.
http://www.offroadvw.net/images/ej20.jpg

and don't get me started on a normal crank wasting all it's power at the start of the stroke where the crank angle is inefficient. Don't these people realise you have ignition timing that gets adjusted to ensure the cylinder pressures from combustion occur at the most efficient crank angles???

pneumatic
09-22-2006, 04:09 AM
You talk alot of crap for a person who knows nothing about revetec or its engines.

Not a particularly professional comment.

If you can explain the test data better than I have, and show me where I have made the incorrect assumptions, then please do so.

I didn't say the engine was doing 12,000rpm. I am saying the when the revetec engine is doing ~4,000rpm, the valve train and pistons were doing equivalent speeds to a conventional engine doing ~12,000rpm.

Therefore any torque and power figures from a revetec engine should be compared to a convential engine that is geared down 3:1.

If I am wrong than explain it to me. My observations on the pulley ratio's for the camshafts will be pretty hard to argue against. It's quite obvious what I say is true from simply looking at the photos.

pneumatic
09-24-2006, 10:06 PM
My 3:1 observation is confirmed by the "let's torque theory.pdf" which is incorrectly linked on the Revetec website. They clearly stated;


When the power take off point is taken from the Primary shaft, power strokes occurring every 240degrees of driveshaft revolution as compared to a conventional RICE which has a power stroke every 720degrees, the CCE has 3 smaller power strokes per 2 revolutions equating to a conventional RICE having 1 large power stroke per 2 revolutions.

Where CCE is the revetec and RICE is a regular internal combustion engine.

That is what I and Stian have been saying. On a normal engine you make power every 2 turns of the crank, the piston goes up and down every turn. But with the Revetec has 3 lobes, so the piston goes up and down every 1/3 turn. It therefore makes power every 2/3 of a turn. Therefore it's internals (piston and valve train) are running 3 x faster than those of a normal engine.

So don't try to argue that, the revetec website even says it.

Even the leap report says the engine produces 6 power strokes per revolution. This compares to 2 power strokes per revolution for an equivalent conventional 4 cylinder engine. This is more proof the internals are running 3:1.

pneumatic
09-24-2006, 10:16 PM
You do not times the rpm by three, the gearing is made so that the output shaft runs 3:2 so if the output shaft is running 4120rpm, the internals are running about 2746rpm.

If this is true than it explains how your getting the subaru valve train to survive such relatively high revs.

If it is true, then Revetec is gearing it up 3:2 to try to get a usable rev range out of it. This means the internals will be effectively geared 2:1 rather than 3:1.

So at an output shaft speed of 4120rpm, the main trilobe shaft is doing 2746rpm (as you have stated). But the pistons are going up and down 3 times more than a conventional engine, so the valve train and pistons are effectively seeing 8240rpm.

So if what you say is true I should be comparing this engine to a conventional engine geared down 2:1. Fine, let's look at that.

First you could compare the 1.38L Revetec vs a 1.3L Suzuki Hayabusa engine as is;

pneumatic
09-24-2006, 10:20 PM
As you can see comparing them with the Hayabusa "ungeared" is not very far due to the much much higher rev range.

So if you add a 2:1 gear reduction to the Hayabusa then the rev ranges become comparible, and the power strokes per revolution of each engine should become the same. As you can see on the attached graph, the Hayabusa engine is so much better, there is no comparison at all. It has nearly double the power and double the torque.

pneumatic
09-25-2006, 06:24 PM
I think this quote says it all;


"The first thing I did was go to Queensland Institute of Technology. I'd come up with the concept but I wanted someone else to verify what I was doing. I presented (the idea) to them and, first off, I said that I was going to increase the level of thermodynamic efficiency beyond 50 percent. They laughed at me. They laughed, so I said 'well, I'll prove it to you.'"

I went to QUT, and I know they get people come in there every year claiming they've got a new fantastic idea, so it's not surprising they laugh. No-one has "proved it to them" yet.

The revetec does have some interesting aspects to it's design, but it is also surrounded by intentionally misleading marketing.

clutch-monkey
09-25-2006, 06:30 PM
I went to QUT
UQ represent!

revetec
10-03-2006, 07:16 PM
Revetec has ben under development for about ten years. At the moment we have not been interested in performance engines so let's refer our engine design to performance in regards to fuel economy. We have produced a very flat torque curve which provides great acceleration right through the range. Our engines have been tested by automotive companies overses and we have replicated this . Another thing is that the fuel consumption remains constant under full load right through the rev range which is not seen in any other engine in the world.

I'll get one thing straight right now. We do not release most of the information about our engine as we protect our technology. We have not disclosed our actual design and guiding system for the pistons. We have almost perfected the design and are currently building our next model which all engines in the future will be based on. We have drastically reduced the size of our engine and reduced the amount of components. We have had no problem with gearing. Because of our new piston guiding system, we have no problem with piston twist.

Our engines in the past have been strictly development engines. Every time we change the Trlobe cam design the balancing changes. This is why up to date we have not balanced any of our engines as it has not been required for the type of development work we have been carrying out. Our new engine is fully balanced. Our reciprocating mass is smaller than other engines of the same capacity, and our stroke is shorter reducing the mass required for balancing. We used the subaru heads on our last engine purely because they roughly suited our last engine layout and our next engine will use heads developed in-house.

I think that most people don't understand our engine due to the fact we have not released certain information. I'll tell everyone now that the cylinder heads are operating at the same speed as a conventional engine. ie. The pistons stroke 2 times (1Xup and 1Xdown) per output shaft revolution (the same as a conventional engine), so there is no overspeeding of the engine's top end. Please remember we have not released all engine features and operation information. You will all have to be a bit patient.

I'll also state now that the formulas that work out power and torque do not work on our engine so all of you engineers that are trying to work out figures for our engine, your standard engine calculations will not work. We have proved this to several large automotive manufacturers and the like plus the figures we get in actual testing verify this.

A development program is just that. Trialling different engine layouts to evaluate different design features. Trialling a new design always creates unforseen problems and failures which then steer the design into the correct layout. Failures are normal for a development program, as with every new design longer endurance testing takes place. We are now in a postion that our next engine is ready for the testing required by engine manufacturers to evaluate in performance, fuel economy and initial endurance testing. Every automotive manufacturer in each region has different operating enviroments. So each engine has to be tested and modified to reach those standards in each region. Say for instance that an engine in Australia is different from one in another country even though the car model is the same. This is why the final endurance testing is not done by us rather an by the automotive company evaluating the engine technology for production.

What I can say is that we are nearing the end of development that is required before production of our engine is performed.

Stay tuned to our website www.revetec.com over the coming months as soon we are going to release info about our new engine. We are very excited about it and it will suprise everone in the engine field. We have now lodged a new patent world wide on the new design.

I will check this forum time to time so if you have any questions please post them as I will try to answer them when I have time.

Cheers
Brad Howell-Smith

revetec
10-03-2006, 07:35 PM
The comment about misleading marketing is incorrect. All marketing the company has released is acurate. We are not bound to release all information about our engine and for security of our technology we reserve the right to hold back information. I have just returned from overseas where I presented to a board of about 8 senior engineers from a leading automotive supplier and the statement from them was "this is a step up technology".

We have proven in actual testing our flat torque curve and a flat fuel usage over a varying rev range. This has been done by a leading automtive company in their facility, fully independantly. I know many of you out there have a lot of questions because you don't have the full picture about what we are doing and I hope to disclose the rest of the information soon. I can say that we have presented to many of the world's top engine manufacturers including 2 Japanese car manufacturers and we have been able to satisfy all their questions posed to us. This technology is hard for them to comprehend so I don't expect you all here to understand what we are doing from the limited information.

As regards to the 1.3L Suzuki Hayabusa engine. Outright performance is not what this is all about. This engine is all about saving fuel by providing consistant torque throughout the rev range reducing the need to rev an engine into the higher power and rev range. By doing this fuel consumption is reduced dramatically. No doubt performance models will evolve to exceed conventional engines in the performance area. I know most of you are interested in the perforance area but I'll tell you now that that is not where most of the market sits. The current engines are directed at markets where fuel usage and pollution problems exist.

Regards
Brad Howell-Smith

revetec
10-03-2006, 08:36 PM
Dear Pneumatic,

Firstly that you are quoting old reports that the engine does 6 strokes per rev. The graph you are showing is of a revetec engine that has 2 strokes per rev. You may note that in the pictures that the valve train is running a 3:2 ratio on the belts but what is not shown is the 1:3 to the output shaft as the output shaft on that engine does not protude out of the engine case at the front. Maybe I should get our website design company to update some information that we can disclose to make things clearer.

Secondly, the engine you are comparing is a high performance engine, not an engine setup for a production car with only fuel economy and emissions in mind. Performance models will evolve but even the valve grind we are using is similar to existing automtive engines that are manufactured with economy in mind. Let's compare the Toyota Prius engine with the 1.3L Suzuki Hayabusa engine. Or the sukuki engine with a F1 engine. They are as different as the comparison you are making so it is meaningless. We have compared our engine to the prius engine (Minus hybrid) and the vectra engine that is currently in production. Two engines that provide good fuel economy.

Does your suzuki engine feel as powerful at 1,500rpm as 6,000rpm? Your engine feels most powerful (best acceleration) where the torque peak occurs. At 6,000rpm you are using 3-4 times the fuel to accelerate the same. Have you ever seen a BMEP pressure map and then compared it to a mechanical efficincy graph. It is funny to think you believe that the peak pressure is only at the same point of a crankshaft's maximum efficincy point and there is no pressure on the piston at any other point. Fuel mixtures, load and rev range vary the peak pressure's postion. Ignition timing get's the pressure point as close to this position but has limitations to the amount that can be used due to detonation and the like. If you were to graph the above mentioned at the maximum point you will realise that the losses are around 36%. It is far worse at lower rpm's and at a partial throttle, where most driving occurs. Please find the thermal efficiency figures of the suzuki engine at a varying load and rev range, especially at the point where most operation occurs. The proplem occurs in evaluating an engine when the peak power is considered.

A friend of mine had a truck which had high torque at low revs which he replaced with another with higher power. He found that the new truck had to be revved higher to produce the power. Fuel economy was worse under the same operation conditions and he felt he had to abuse the engine to gain the same performance with the same load. This is why a large torque band in a lower rev range is so important.

I'm not having a go at you. I'm just trying to explain why we are doing what we are doing. There are many things that we have experienced in our testing we are still trying to fully quantify, such as when we program an engine fuel injection on the dyno that the fuel injector duty cycle reduces when the revs and load are increased. This has never been seen in an engine before and it will take many years of analysis to fully understand what we have experienced in hard tests. All I can say is that we have had to take engines OS to prove the torque and fuel delivery maps under independant testing by because it seems impossible to engine manufacturers that we are talking to. They have to see it with their own eyes on their own equipment. This has been done.

Regards
Brad Howell-Smith

revetec
10-03-2006, 08:52 PM
Dear Pneumatic,

So let us refer to your graph before you put the gearing factor in which is incorrect due to the fact that those figures were produced on an engine with 2 strokes per rev being the same as the compared engine. We are producing more power in the normal automotive rev range and producing almost the same peak torque at 3,500rpm compared with 6,500rpm of the 1.3L Suzuki Hayabusa engine, when the fuel usage would probably be double. Note again that the lower the revs that the torque is applied the better. This is an automotive vehicle engine prototype. Knowing this I think you would be silly to say that our engine doesn't save fuel dramatically in an automotive application. Maybe in the future we we develop an engine that has the same application as the Suzuki Hayabusa engine. The figures would be very interesting due to providing engine breathing at the same RPM and extending the flat torque curve to a higher RPM range. We actually produced a better and dead flat torque curve very recently at a leading engine manufacturers facility. Our next engine will even be better.

http://www.ultimatecarpage.com/forum/attachment.php?attachmentid=212468&d=1159161366

manolis
10-03-2006, 10:50 PM
I came across this thread today.

Please take a look at http://www.pattakon.com/greco/index.html or start from http://www.pattakon.com
and select either the ‘GRECO animations’ or the ‘GRECO theory’ topics. There are some 20 animations.

Then forget all about crankless engines, return to the present conventional TESTED technology and take a good look at http://www.pattakon.com/pre/index.html (or get into pattakon's site and select the Pulling Rod Engine – NOT the Pulling Piston Engine which is its father – ).
If you have to select just one animation of the Pulling Rod Engine, try the http://www.pattakon.com/pre/PRE13.exe or
http://www.pattakon.com/pre/PRE14.exe or http://www.pattakon.com/pre/blueprint.pdf .

Thank you
Manolis Pattakos

revetec
10-04-2006, 09:54 PM
Dear Manolis,

Re: Pull rod engine

Unless you are doing formula1 RPM's (18,000RPM) a conrod ratio of around 1.65:1 is desireable to achieve the correct piston acceleration. The higher the RPM's the higher the conrod ratio required. A normal car is around 1.6:1 - 1.7:1. Is this Pull rod configuration engine a automotive production engine or a 18,000RPM one? If it is aimed at the car market then:

This company doesn't know anything about breathing. Any engine of this kind has a slower initial piston speed which decreases the initial gas flow past the valve. We have investigated using a cam with a perfect sine wave in piston acceleration and we have found that any engine with a con-rod to stroke ratio of anything over 1.7:1 reduces breathing and requires supercharging at lower RPMs or non standard valve timing when getting over 2:1. The problem with many people is that they don't understand engines properly and even though some theory may look good and the design looks simple, doesn't mean there are no inherant problems with what they are trying to do.
BTW. Let's see an actual engine run with figures of this pull rod engine.

Brad
PS. I modified my response so as not to be so agressive as I think I went overboard and was probably having a bad day reading all the threads. Sorry If I upset anyone! :-)

manolis
10-05-2006, 10:07 PM
Dear Brand,

Thank you for your reply.


You wrote : This company doesn't know anything about breathing. Any engine of this kind has a slower initial piston speed which decreases the initial gas flow past the valve. We have investigated using a cam with a perfect sine wave in piston acceleration and we have found that any engine with a con-rod to stroke ratio of anything over 1.7:1 cannot breathe properly and requires supercharging.

It seems you never heard that all Formula1 and GP-moto engines use con-rod to stroke ratio well above 1.7:1 (most above 2.0:1). And they do not use supercharging. It seems they know nothing about breathing (AND combustion).




You wrote : The problem with amatures like these people is that they don't understand engines and even though some theory may look good and the design looks simple, doesn't mean there are no inherant problems with what they are trying to do. Companies like this just burn investors money without having any prospect of getting an engine to perform or get to production.

I declare publicly today, to any one of pattakon’s investors to brink me their shares and I will buy them - immediately - a million times their initial price in US dollars (i.e. for each dollar the investor – any investor – gave, he will take a million dollars in return).

Pattakon makes the only continuous VVA (variable valve actuation) engine in the world capable of revving over 9000 rpm. BMW do not use their valvetronic VVA system in their sport cars because they cannot.
We can arrange a test drive for you (or any other professional). Take a look at the http://www.pattakon.com/vva/VVA_Idle/VVA_Idle.htm and the video http://www.pattakon.com/vvar/OnBoard/A1.MOV etc, etc in www.pattakon.com site.

Once again: I call any professional willing to have a test drive with pattakon’s cars to call me.
And a special offer – it is the challenge you asked for -for you: come for a test drive in Athens and if you see less than I claim, I will pay your first class airplane tickets.

Just to find out who is giving the engine development industry a bad name and who is burning investors money.




You wrote : Let's see an actual engine run with figures of this pull rod engine. You'll never find one now or in the future because in real life it wont work properly.

I admit, there is no yet a Pulling Rod Engine prototype.
But take a look at the pattakon’s US patent 6,062,187 and then HONDA’s US patents 6,763,796 and US 6,786,189 ( http://www.uspto.gov/patft/index.html ). It seems HONDA’s staff do not know that con-rod to stroke ratios above 1.7 cannot breathe properly. Please inform HONDA, too, to stop wasting their time over such crap.


Thanks
Manolis Pattakos

acemotorsport
10-05-2006, 10:19 PM
what the.........

revetec
10-08-2006, 08:42 PM
Dear Manolis,

Ferrari F1 engines use slightly greater than a 2:1 conrod ratio but this is to reduce side thrust and allows a lighter piston to be used but most importantly to lower the piston speed down to 24.8 m/s when doing 18,000rpm. Some other formula 1 engines are using down to 1.7:1 conrod stroke ratio and a stroke down to almost 41mm when looking for better performance around the 12,000-15,000 rev range giving similar piston speeds at the desired rpm range. An Evo uses a 1.66:1 conrod ratio which puts the piston speed at maximum acceleration around 20 m/s at 8,000rpm which is a good basis for talking on an on-road application.

If you look at the piston speed chart below you will see that the sweetspot for good initial piston speed creating good velocity past the valves happens between 1.5:1 and 1.7:1 (130mm and 148mm) at which provide low piston speed at BDC for volumetric efficiency and mid piston speed 18-20 m/s. Above 2:1 initial velocity is decreased and BDC dwell is decreased. The endless conrod theory gives a very slow initial speed and hardly any dwell. The pull rod engine would be even slower in initial velocity and piston speed would be more constant an provide less dwell at BDC.
Below 1.5:1 the initial velocity suffers also shown in the plotting of the ratio of 1.2:1 which is too low.
There are many engines that have a conrod ratio above 1.7:1 that perform. Looking at the piston speed graph it would be advantageous to lay around 1.6-1.7:1 if the engine's redline was about 7,000rpm to 8,000rpm

Changing a conrod ratio also changes the torque application angles of the conrod. Maybe the engines you are referring to are trying to achieve a better drivability by changing the position of maximum mechanical advantagein regards to the point of maximum cylinder pressure on the combustion stroke.

I have been talking about breathing not about the combustion cycle.

What you maybe missing from my point is that our engine can utilise the best piston acceleration for breathing while providing the position of maximum mechanical efficiency across the range. This means no matter what ratio is selected for breathing is optimised and independant of the point of mechanical efficiency on the power stroke.

On some other performance engines the valve timing is wilder or in the Honda's case variable valve timing is utilised. Inefficiencies in breathing caused by selecting a non-optimum conrod ratio can be rectified by using these two mods but if we are talking about conrod ratios as it effects piston acceleration and breathing on two identical set up engines the graph shows the sweetspot.

I was talking about the pull rod engine and the effects caused by such designs in regard to optimum conrod ratios.

The chart doesn't lie. It's pure math of a mechanical design of a conrod engine.

Offsetting the gudgeon pin in either direction from standard type settings also change these graphs. Offset used was a standard Evo.
http://i84.photobucket.com/albums/k6/revetec/conrodratio.jpg

revetec
10-08-2006, 09:21 PM
Dear Manolis,

Again Sorry about the agressive post as I was a bit revved up by the threads because everyone was assuming so much without actually knowing the setup used in our last engine, and I jumped in with both feet.

Let's look at the combustion cycle at 18,000rpm. Such a wide range of rpms would require a longer conrod ratio to work effectivelyas you require to lengthen the band of degrees that the piston is able to transfer power effectively. F1 is hardly the market to compare any on-road engine to.

I would love to see a pull rod engine run and the figures. I see too many new engines that don't make it to production mainly due to unforseen problems and characteristics. I just like to put it out there and healthy controversial discussion is great because it gets everone thinking. I hope the pull rod engine guys read this thread as it may be of some use to them as it maybe something either they have not thought about due to being early in development or they have some theory other than commonly known in the engine design field. In the latter it would be great to hear their thoughts on this subject. I'd love to hear from them as I might be able to help. I would imagine that the pull rod engine will provide optimum performance at very high RPM ranges going on the probable resulting conrod ratio, but maybe not desirable for automotive use as the piston speed will be very slow initially.

I still suggest supercharging of this engine at lower RPM ranges due to the low initial piston speeds. I probably wasn't that clear before. I'm always only looking at operating ranges that engines use in mainstream manufacturing.

Our engine can be easily modified to run any conrod ratio and we have tried a few ratios in our development program using identical setups in the same RPM ranges. We have experienced exactly what the graphs suggest would happen, so it is not just theory, we've done it in practise.

If you are involved in the pull rod engine, get them to contact me. My contact details are posted at http://www.revetec.com

PS. Never doubted the benifits of variable valve timing and theirs is probably good.

Alastor
10-09-2006, 08:36 PM
...
http://i84.photobucket.com/albums/k6/revetec/conrodratio.jpg

Something is wrong with "100 mm Rod Length" curve.

pneumatic
10-09-2006, 08:52 PM
Interesting thread. I notice some threads such as those by "richy33" have mysteriously disappeared.

Brad,

You make many claims, but have no evidence for any of them. So understand that people will be sceptical.

I am a chartered professional engineer, not some armchair critic.

The problem I have is with the comments like this;

I'll also state now that the formulas that work out power and torque do not work on our engine so all of you engineers that are trying to work out figures for our engine, your standard engine calculations will not work.

That statement is absolutely ridiculous. I am an engineer, so I work in the base metric units. m, rad/s, N*m, W. I don't use any silly formulae that have factors to account for imperial units.

A force is measured in Newtons.
A torque is a Force x a radius = Newton.meters.
Power is torque x rotational speed = Watts.

There is no arguing this, beause that is by definition what those terms are.

If you believe it doesn't work on your engine, then you are doing something wrong when calculating these. This I can guarantee. The power and torque must be calculated at the same shaft at that particular shafts rpm.


We have proven in actual testing our flat torque curve and a flat fuel usage over a varying rev range

Your published test results so far do not show a flat torque curve, it is no flatter than a conventional engine...


Another thing is that the fuel consumption remains constant under full load right through the rev range which is not seen in any other engine in the world.

Well we haven't seen that from your engine either yet, so let's not get ahead of ourselves.

The "directors announcement" dated 6-Oct-06 states;

Also noted a further important characteristic aspect namely that our engine at full throttle used the approximately the same amount of fuel at 4,000 rpm as it did at 2,000rpm which was very exciting.

What do you mean by "same amount of fuel". Is this a fuel flow rate like L/min? Is so this is impossible, unless the torque at 4,000rpm was half what it was at 2,000rpm.

Has a reliable source actually created a full engine characteristics map for this engine? Did they plot pressure-volume diagrams, brake mean effective pressure, thermal efficiency, specific fuel consumption, etc? I am guessing not as the engine threw a cam-belt during the tests at only 4500rpm.

It's probably useless trying to discuss this any further for now, because I have made completely logical observations based on the facts and information available so far.

You have made unproven claims.

If you want to clear some things up, then let's do so.


I'll tell everyone now that the cylinder heads are operating at the same speed as a conventional engine. ie. The pistons stroke 2 times (1Xup and 1Xdown) per output shaft revolution (the same as a conventional engine),

In order to achieve this, your output shaft must be essentially geared up at a 3:1 ratio, so the output shaft spins 3 times faster than the tri-lobe. Is this correct?

Don't get me wrong here, I am all for new technologies, especially when it is Australian. But some of the claims so far are pretty wild, particularly when there is no proof what so-ever of any of the claims.

santostripoli
10-09-2006, 10:17 PM
Pneumatic

You have raised some very interesting points, backed up by facts & sound engineering logic.

I think you are being a little unfair with Brad, it is obvious that he cannot disclose certain information. He has both hands tied-up and you are throwing all the punches. I have a strong feeling that when his hands are untied, he will strike the strike the biggest blow; just give him time and I am sure he will reveal all.

Now, I am not an engineer, I am a business person who invests his time in biotechnology. However, I have been tracking this Revetec invention for quite some time. One thing I do know is that a company with the credentials and clout of Mahnindra and Mahindra would not be wasting their time if this technology was not worth their while.

Mahindra has a great deal to benefit from integrating this technology within their product line-up. India is the fifth largest Asian automotive market and has the capability to tap into China's automotive market which is reportedly the world's second largest automotive market. Mahindra are massive and their engineers seem to have a different perspective to this technology then that posted by you.

My point here is that, as Brad noted, let’s be patient and stop asking questions which you know Brad is not able to answer due to intellectual property disclosure implications.

If Brad can introduce a technology that can extend our current oil resource until which time hydrogen fuel cell technology can be utilised practically and logistically (i.e. it may be 40-50 years away) then we should all try and support him.

You seem to have a very deep understanding of engine technology, can I suggest that both Brad and you get together and share some notes?

Brad, you are based in the Gold Coast and Pneumatic you are in Brisbane; you are only 45 minutes away from each other. Brad, I am sure you could benefit greatly from Pneumatics input (and I am sure that he/she) will be happy to sign a non-disclosure statement.

What do you both say?

revetec
10-09-2006, 10:21 PM
Dear Pneumatic,

Our engine transfer characteristic is that the formulae on power and torque uses a constant radius and our engine doesn't. Our cam design gives an infinite variation in an egg shape which can only be performed with a complex calculation which I have explained to universities, car manufacturers and to understand the process would have to be shown in a live explanation. This reason is why we can do what is claimed. Please design a cam yourself then vary it. You'll see the effect yourself. If you are ever able to meet me at one of my seminars please approach me. Please private message me to let me know where in the world you are and next time I'm in your region I'll hook up with you.

On our last trip we achieved a near dead flat curve at a leading manufacturer's facility.

We achieved in our last independent testing at full load: The same fuel consumption at 4,000rpm as at 2,000rpm and doubled the power. Our fuel map drops off with RPM and load which is a characteristic of our engine. We will release Fuel Map and Consumption figures around Xmas as this is currently confidential with the testing independently performed with a large manufacturer who is evaluating our technology.

The testing proceedure recently by the manufacturer was for power/torque/consumption giving total efficiency. BMEP will follow as well as Emissions which are usually 2nd phase of testing. This will come soon after the next round of testing.

Please remember that we are a public listed company and we cannot make any claims that are incorrect or we would be shut down by the governing body for listed companies in Australia being ASIC (Australian Securities and Investment Commission). We can only make claims that we can back up with documentation. This does not mean that we have to disclose all to the public but we must disclose to ASIC.

Yes we are gearing up at 1:3, so yes the output shaft is spinning at 3 times the speed of the Trilobes. There is no smoke and mirrors here. If anything we have losses through that said gearing. If you are local to our prototyping centre (just moved back to the Gold Coast from Sydney) I can explain technology in more detail.

Many engines have made outrageous claims over the years and many development companies haven't come up with the goods. This hindered my project for around 5 years due to lack of investment caused by ill feelings in the investment market against such companies. I can name several but you probably know them also so I'm not going to get into a mud slinging match with them. I will say that one other party in this group released a newsletter claiming they were developing our engine with us. It was quickly retracted after a personal visit.

I have had one company try to steal our ideas and they even set up a company and took investment to do so. After I rang them they quickly relocated to the US. This is why we don't release all information, as there are many people who want an easy ride by ripping off your technology.

Assuming that our info is correct and put yourself in my shoes you wouldn't release all your info in fear of being ripped off also.

We are also bound by agreements with large companies not to disclose infomation unless authorised by them. Many companies will not allow us to disclose that we are talking to them. Only when a contract is signed is either party able to disclose. So sorry I can't disclose all at the moment.

Any info you see released by us regarding any commercial activity is passed by the both parties' legal departments before disclosure. Many modifications are made to the disclosure and often a full picture about our business with other parties is not disclosed. This is unfortunate but a fact of larger business dealings. After all this happens we are bound to disclose this information by ASIC. Actually any information that is not confidential and may effect share price must be disclosed.

revetec
10-09-2006, 10:32 PM
Dear santostripoli,

Thank you for your response. It is hard to discuss in depth what is mostly confidential. You are right by mentioning about Mahindra. I'll state now that no automotive company will talk to anyone with technology without analysing the technology prior and also checking out the company concerned as well as patent protection. No large manufacturer wants to get involved with bogus technology and goes to great lengths to separate themselves from it. Mahindra authorised us to disclose their name and interest in Revetec's technology to ASIC and also to the public. This fact holds weight.

revetec
10-09-2006, 10:40 PM
Dear Alistor,

A very short conrod does reduce acceleration initially. The graph is acurate. If you wish to email me I can email you the calculation sheet if you like. Here is a simple sketch of the calculation.

http://i84.photobucket.com/albums/k6/revetec/sketchconrodcalc.jpg

Sorry if this is getting a little technical for some. Just wanted to answer as much as I can to the engineers out there.

pneumatic
10-09-2006, 11:08 PM
Pneumatic
I think you are being a little unfair with Brad

If I have been, I apologise.

I understand they need to protect their technology and intellectual property. But I can't accept their claims with no proof.


Our engine transfer characteristic is that the formulae on power and torque uses a constant radius and our engine doesn't. Our cam design gives an infinite variation in an egg shape which can only be performed with a complex calculation which I have explained to universities, car manufacturers and to understand the process would have to be shown in a live explanation. This reason is why we can do what is claimed.

Brad, I think the reason you rub engineers up the wrong way is that perhaps you don't fully understand the engineering principals they are defending. Engineers understand how a cam and your tri-lobe works, there is nothing tricky about it. It is obvious the effective radius changes, it does for a crankshaft too, just in a different way.

But that has nothing to do with the relationship between power and torque. How do you think a dyno measures power? It simply measures the torque and multiplies it by the rotational speed to calculate the power. It doesn't care if a cam or a crankshaft generated that torque. You can only ever measure the torque and speed, and calculate the power.


same fuel consumption at 4,000rpm as at 2,000rpm and doubled the power

Please be specific on what units your fuel consumption is measured in. It could not possibly be a fuel flow rate, because for the same efficiency you will need double the fuel to make double the power. This is simple engineering / science.

You must be talking brake specific fuel consumption / specific fuel consumption. If that is the case, it should be pointed out that conventional engines can achieve similar results.

It also means the statement in the recent director's announcement is very misleading, as fuel consumption is quite different. The announcement suggests something like "our engine uses the same volumetric flow rate of fuel to make 100HP at 4000rpm as it does to make 50HP at 2000rpm" which is not possible (unless it is twice as efficient at 4,000rpm).

pneumatic
10-09-2006, 11:24 PM
Brad,

This is the claim on your website that pi**ed off a lot of engineers, because they hate seeing people claiming to cheat science.


The power output is similar to a conventional engine, but given that the significant improvement in torque output is almost three times that of a conventional engine

For the power output to be the same, but one engine to have 3 times the torque, that engine must also then produce that torque at 1/3 of the rpm.

This is not open for arguement, it is the laws of physics / engineering / science.

The point is an engine that produces 3 times the torque at 1/3 the rpm is NOT better than the engine it is compared against. If you produce 50kW you produce 50kW. All it means is the engine that produces the 3xtorque at 1/3rpm must be geared 3 times higher to be capable of achieving the same vehicle speeds. If this is done the acceleration of both will be the same.

That also cannot be argued. So us engineers have said the marketing is misleading, because it doesn't tell the general population that 3 times the torque at 1/3 the rpm is NOT any better. It is just different.

From what you have said above, the revetec now gears up the output shaft 3:1. Therefore this 3xtorque has now been reduced to 1xtorque, and the 1/3rpm has been increased to 1xrpm. So with the 3:1 gearing the rpms, torques and powers are now comparable to a conventional engine. This is what I and others have been saying the whole way along.

You have to realise that when the general public (and the first 6 pages of this thread) read your marketing documents, they think your engine is 300% more efficient / better than a conventional engine - which is not correct.

revetec
10-09-2006, 11:29 PM
Dear Pneumatic,

Our engine does some funny things, some of which we can't explain. One is that at a constant lambda set to the fuel mixture of 14.7:1 the fuel consumpton decreases with revs and load.

I don't know whether you are familiar with Wayne Jones (previously from Bert Jones racing cams, Joint owner of Haltech and now engine tuner for a lot of race teams including the Stones Brothers) but he has been our leading programmer for years back to our Motec association. Everytime we get someone involved such as Haltech he states to new consultants to forget everything they know about engine maps in fuel and spark.

Our fuel map drops off as load and speed are increased. Our engine also likes alot of ignition timing. Our piston is over twice as high in the cylinder at the same degree of rotation when the spark plug fires. We also do not need as much enrichment on cold starts (Usually 1/4 of a conventional engine). Due to this fact the fuel molecules are closer together when ignition takes place and being so oversquare and having such a large piston dwell we have found better heat soak in the next firing cycle. All this and other factors that are different have caused us to experience many characteristics that are beneficial but were also unexpected.

Due to our budget we have been concentrating on refining mechanical layouts and even though we have experienced so very unusual and exciting benefits we have not had the budget to revisit and prove many of the findings in actual tests.

Can I also state that in our tests power and torque have not been like your and my understandings of engineering suggests they should be. In one test maximum torque was at 1,800rpm and held steady to 4,200rpm even though the power curve was similar to a conventional engine. This is why it is very exciting times.

Yes the fuel used and fuel flow rate did not change much although the revs at full load doubled. Very hard for me to believe as I didn't expect that it would be as good as that due to my calculations to use 30% less. This was proved in Mahindra's engine test centre which has 7 Dyno rooms. I can't wait for the next round of trials with our 1350cc engine and our new engine currently in design which should be finished around Xmas if the grant comes though in two weeks.

revetec
10-09-2006, 11:38 PM
BTW: We are planning to trial cams with 1.6:1/1.7:1 and 1.9:1 conrod ratios in our next engine which will have the same bore/stroke and setups. Hope to publish this data here when I get it so we can all see the difference in performance and characterists.

revetec
10-09-2006, 11:53 PM
Dear Pneumatic,

As for the 300% more torque it depends on the setup of our engine. Many analysis' have been done on our design and the one that is shown is a low rev setup (from 2003) which we do not use now due to our automotive setup for our clients programs.

We can alter the torque lever to a great degree. Although testing of these setups have been performed, such radical setups won't make it to production. I will get an update to our current setup soon on our website. We are currently increasing torque by cam design picking up around 30% torque across the range. The previous setup does not suit any current project due to the low speed torque handling of transmissions limitations so we are not pursuing this characteristic and setup of such an engine currently. We did have an engine which is currently at Mahindra for training purposes that is 450cc and produces a peak torque of 78Nm at 1,800rpm. Again this engine is purly for pushing the envelope in design and has been disassembled in my presence 2 weeks ago where I also trained their staff on the technology limits.

pneumatic
10-09-2006, 11:57 PM
Can I also state that in our tests power and torque have not been like your and my understandings of engineering suggests they should be. In one test maximum torque was at 1,800rpm and held steady to 4,200rpm even though the power curve was similar to a conventional engine.

This doesn't make sense, because the dyno only measures torque and rpm. So you cannot get a power curve that disagrees with the torque curve. Because the dyno calculates the power from the torque.

So if your power curve doesn't match your torque curve, then your dyno is not working (performing the calculations) properly.

Well designed conventional engines get relatively flat torque curves too. The torque curve of the V6 in my car has only about a 10% variation between 2,500rpm and 6,000rpm. All it has is a 4-stage variable length intake. All standard Mazda stuff. It therefore produces a fairly linear power curve.

Maybe I need to sign a confidentiality agreement and have a look at your numbers for you ;)

revetec
10-10-2006, 12:06 AM
It does make sense! As RPM's increase the torque stays flat so the calculation of power increases with revs.

See the torque lever is high initially due to higher initial mechanical advantage to the output shaft. So we have higher torque at lower RPM's and hold it. As RPM's increase, power increases. Our biggest benefit is at part throttle at cruise when the peak pressure is very early in the stroke due to a lean mixture being ignitied at a high advance. Providing an earlier good mechanical transfer is of huge benefit.

I might say now that our last engine had a stroke of only 50mm (A conventional engine would have a torque lever of 25mm) but produced a torque lever of around 80mm over almost 80% of the piston stroke whereas a conventional engine produces a good torque lever over about 30% of its stroke.

santostripoli
10-10-2006, 12:08 AM
Gents

The best thing for all parties is for the two of you to get together. Pneumatic, are you in Brisbane, yes or no? If yes, then meet up with Brad. Please contact him at his office and meet up and discuss these issues.

Now, as soon as you have both reviewed the stats and the technology, you can get back on to this forum tell us simple folk what it all means.

I want to know whether or not it is worth following this or not.


:eek:

revetec
10-10-2006, 12:11 AM
We are achieving this flat torque curve without variable length intakes or variable valve timing. My dyno is very acurate and has been independantly checked, calibrated and certified. We are simply maximising the pressure in the cylinder transfered to the output shaft whereas a crank can only do so much. We also defect a further 60% of downforce on a main bearing journal into rotational force (Let that one mess with your minds) wasting only 11% in downforce instead of 26%.

revetec
10-10-2006, 12:22 AM
Yeah! Lets get together and chew some fat. I have proved to many universities and around a dozen engine manufacturers that losses in an engine don't work out. Probably the biggest is frictional losses. I have argued that most friction causes heat and is measured in the heat loss measurements. Mechanical inefficiencies are the biggest losses. I'll explain....valve springs create resistance to move and consume power, so does the crank as you can imagine that at 20 degrees ATDC that the torque lever is small but the cylinder pressure is high which is a big loss in mechanical efficiency. A piston rubbing on a cylinder bore Whereas the friction causes heat is measured elsewhere such as the cooling system heat loss. My original pitch addressed calculating all the losses and I found a 26% void in the calculation that didn't address the engines mechanics. I have proved this to every engine and car company I have met. Pneumatic is not the only person who has challegned me on points like the ones he has posed. I had the same arguement with the GM of a Japanese car manufacturers' R&D department when they asked me over to Japan to talk. I quickly explained the function and losses of an engine and he had to agree with me, which he did begrudgingly.

pneumatic
10-10-2006, 12:27 AM
The laws of science still hold. If something seems unexplainable it just means it hasn't been explained yet, not that it can't be explained :D

If you have Excel 2000 or better on your computer than go here and download this very detailed spreadsheet program I have developed;
http://www.offroadvw.net/exceldyno/

If you play with that for a bit, and mess around with engines with 300% torque at 1/3rpm and 3 times taller gearboxes, you also see everything I said is true. It will help some people understand how changing certain things effects the vehicle.

You also see on the engine sheet that you don't need to enter both power and torque, because one is simply calculated from the other.

A visit is probably premature at the moment. I just need to look at test data.

revetec
10-10-2006, 01:05 AM
I have an excel spreadsheet I have developed that I already use for calculations.

It calculates trilobe cam design, VE predictions and calcs, power estimations, engine dynamics including side thrust and piston position/accelerations and velocities, injector selection, ram or organ tube optimum lengths, valve and port size selection and lift, valve cam selection, standard gearbox data and selections with predicted speeds, vehicle performance as well as 1/4 mile,, plus heaps more.

Everything you need to design a Revetec or standard engine. It's a work in progress so it's not quite fully linked yet but 90% there. Thanks anyway!

pneumatic
10-10-2006, 02:39 AM
Everything you need to design a Revetec or standard engine.

Would be interesting to see that spreadsheet, if you ever decide to release it to the masses :)

I guess we will have to wait until you release more test data. Arguing the theory side of things is pointless without some test data backing things up.

manolis
10-12-2006, 09:03 PM
A few corrections

Brad, in your acceleration versus conrod to stroke ratio there are two errors:
As Alastor wrote, the acceleration curve for 100 mm conrod is wrong.
Also the factor 1000 in the Y-axis title is mistaken too. The correct is 1,000,000.
Here is the corrected plot.

http://www.pattakon.com/tempman/piston_acc.GIF

Brad, the conrod to stroke ratio has no effect on the mean piston speed. Only the maximum piston speed is increased for shorter conrod.

And Brad, as shown in the plot above, conrod to stroke ratio smaller than 1.5 increases even more the velocity around TDC while BDC dwell increases. But the thrust loads and the need for strong piston (i.e. heavy piston) imposes limits for the minimum conrod length.

Brad's / Revetec's work is important and respectable. They try to get in practice a different kinematic mechanism for the internal combustion engines.


PRE engine

Pattakon’s VVA has infinite modes of operation (as compared with the two only modes the Honda’s VTEC system provides), selected directly by driver’s right foot. So the conrod to stroke ratio, which may not be the perfect one for a specific valve lift profile, can be rectified by pattakon’s VVA system throughout the entire rev range. So, the pattakon PRE (pulling rod engine) combined to the pattakon VVA system seems a good solution. Another solution is the valve-less version of PRE engine.
Supercharging is always an option for the PRE, but the NA engine is simpler.

http://www.pattakon.com/pre/PRE13.exe
http://www.pattakon.com/pre/PRE14.exe
http://www.pattakon.com/pre/blueprint.pdf

If the total efficiency (due to improved combustion) and the pick power and the torque distribution are improved with the PRE engine, then who cares about the optimisation of particular factors like conrod to stroke ratio.


Harmonic engine

Pattakon has experience in making harmonic piston engines. A few photos are shown at http://www.pattakon.com/ppe/ppe.htm) . Here it is a single cylinder prototype, made more than 10 years ago.

http://www.pattakon.com/ppe/ppe_files/image003.jpg

It is completely vibration free (it can stand free on the floor, revving from 1000 to 9000 rpm, without any tendency to move). It was tested providing 3 Kp*m of torque around 3500 rpm from 354cc (bore 75mm, stroke 80mm). Info concerning this prototype is at www.pattakon.com/educ/harmonic.exe (details at selection 15). It seems it manages breathing too well for an 'infinite' rod - or pure sinusoidal - piston motion.


Pattakon's GRECO engine

I respect Brad's claim that he has to keep revetec's secrets.
But the rest ones don't. So they can comment the following.

Pattakon's GRECO crankless engine basic mechanism versus Revetec's (for the same piston stroke):
http://www.pattakon.com/tempman/TRI_SINGLE_lobe.GIF

Pattakon's GRECO single cylinder.It is actualy made by two pieces, a shaft (or call it cam-shaft) and a piston having some Yoke roller bearings on it. That simple. That short. No need for a single gear.
http://www.pattakon.com/tempman/greco_single.JPG

The application of the previous in a four in line GRECO engine having a unique shaft
http://www.pattakon.com/tempman/I4.JPG

Pattakon's 8 cylinder in H arrengement GRECO engine having two counter-rotating camshafts
http://www.pattakon.com/tempman/greco8.JPG

At http://www.pattakon.com/greco/index.html you can download some 20 animations regarding various arrangents and details of GRECO.


On the other hand, the PRE engine uses current - tested technology.

Thanks
Manolis Pattakos

manolis
10-16-2006, 09:08 PM
Compared to the unconventional crankless engines like Revetec's trilobe, Pattakon's single lobe GRECO etc designs, Pattakon-PRE engine may seem as a very conventional design.

But think of a Junkers-PRE engine (with Otto or Diesel cycle). Like this one:

http://www.pattakon.com/tempman/pre_junkers.JPG

What do you think about its power concentration, its thermal efficiency, its reliability , its smoothness and its peak power rpm?

If it is as good as theory says, the next step is to think of an application like this:

http://www.pattakon.com/tempman/fly.JPG

Thanks
Manolis Pattakos

pneumatic
10-18-2006, 02:38 AM
But think of a Junkers-PRE engine (with Otto or Diesel cycle). Like this one:

It's like a 4 cylinder 2-stroke with reed valves, and where 2 cylinders are supercharging the other 2. The not so pretty part is connecting the two cranks together to keep them in synch.

revetec
10-18-2006, 09:32 PM
Interesting animations. I supose I can comment on the rollers that control side thrust by saying that roller bearings don't like stop start reverse operation but I supose they should or probably are using a slide type of arrangement when building one. I wouldn't mind seeing what torque lever length they have at what degrees of rotation. If I have time to graph it I will but is there anyone out there that has the time to do it and post it?

I would also probably comment that their cam design would probably not be as flexible in design options as ours. I then looked at the animation of the multi bearing/lobed engine an can see the outer cams cutting through the opposite shaft. Hmmm...

The multi cylinder engine has cutouts in the shafts to allow the opposite cam to pass through which looks to be a weak link.

http://i84.photobucket.com/albums/k6/revetec/grecomulti.jpg

The bearings also look very small on the outer cams. There are other issues but like our company they may not be disclosing updates and newer designs. I would be interested to see if they have successfully tested any of the shown designs or others other than their valve train designs.

BTW. in 2-3 days our website will be updated. All previous information which was correct at the time of posting but is out of date now due to design and configuration changes will be removed. So no 3:1 gearing comments to confuse figures posted with current engine layouts and operation. The 3:1 gearing was an older special use engine and hasn't been used for 3 years.

I think that when we release details of our new design when our website is updated you all would be a bit interested in the compactness of our latest design.

Manolis: Alastor and yourself were correct about the 100mm conrod. I went back to my calculation sheet and realised that I had played with it and resaved it by mistake. Ouch! I should have spent more time to make sure that it was correct and not assume it was correct. I suppose my only defence is that I'm very busy designing our new engine and didn't have the time to go through the speadsheet and make sure it was correct. I will be more careful in the future because I can tell you all are very passionate about engines and have a high degree of knowledge so I'll only post here if I triple check everything.... :-)

Cheers

santostripoli
10-19-2006, 12:04 AM
Brad

Great to hear your response regarding updating the web site in addition to clarifying the issue regarding the 3:1 gearing issue.

We await the updated web site details and I for one look forward to the engine stats for this new engine.

I am curioous, given the fuel effeciency characteristics of your engine I would expect that if you were to inetgrate your technology into a petrol/electric application similar to Honda & Toyota that the fuel economy figures would be quite outstanding. Especially given you coment regarding the compactness of your new engine (it will obviously weigh less) so it would also have a power 2 weight advanatge in addition to packaging effeciency.

Are there any plans for a pterol/electric concept perhaps in the future?

manolis
10-19-2006, 05:57 AM
It's like a 4 cylinder 2-stroke with reed valves, and where 2 cylinders are supercharging the other 2. The not so pretty part is connecting the two cranks together to keep them in synch.

Pneumatic,

If the diameter of the low pressure side of the pistons is greater than the diameter of the ‘combustion’ side of the pistons, like:
http://www.pattakon.com/tempman/pre_junkers_supercharged.JPG
the engine is supercharged.

The synchronization of the two crankshafts is a problem.
But think that in case the load is directly attached to both crankshafts,
as happens in the Portable Flyer or in an ‘absolutely vibration free’ power plan –think of two identical electric generators driven directly by the two crankshaft – or in an outboard engine having one propeller on each crankshaft etc,
the synchronization is very easy and light, as it transfers no loads: the torque goes directly to the load.

In motorcycles the rule is the “primary transmission’, so the following PRE arrangement

http://www.pattakon.com/tempman/pre_junkers_clutch.JPG

for a motorcycles adds nothing – compared to conventional - as it uses the ‘primary transmission to a main shaft (having the clutch on it) as the synchronization.
Note here that the synchronization of the two crankshafts of the PRE engine is not critical and needs not special accuracy, i.e. the PRE will still operate even if you change the phase of the two crankshafts for a few degrees.
And here comes another characteristic / advantage of the PRE : if you deliberately change the phase difference of the two crankshaft more and more, then you have the way to change the compression ratio of the PRE without other complications. If there is interest, I will make some animation to explain the case.

Thanks
Manolis Pattakos

manolis
10-19-2006, 06:02 AM
Interesting animations. I supose I can comment on the rollers that control side thrust by saying that roller bearings don't like stop start reverse operation but I supose they should or probably are using a slide type of arrangement when building one. I wouldn't mind seeing what torque lever length they have at what degrees of rotation. If I have time to graph it I will but is there anyone out there that has the time to do it and post it?

I would also probably comment that their cam design would probably not be as flexible in design options as ours. I then looked at the animation of the multi bearing/lobed engine an can see the outer cams cutting through the opposite shaft. Hmmm...


. . . . . .

Manolis: Alastor and yourself were correct about the 100mm conrod. I went back to my calculation sheet and realised that I had played with it and resaved it by mistake. Ouch! I should have spent more time to make sure that it was correct and not assume it was correct. I suppose my only defence is that I'm very busy designing our new engine and didn't have the time to go through the speadsheet and make sure it was correct. I will be more careful in the future because I can tell you all are very passionate about engines and have a high degree of knowledge so I'll only post here if I triple check everything.... :-)

Cheers

Brad,

Pattakon’s GRECO cam design is as flexible as the trilobe cam design, i.e. it can realize any reciprocating motion that the trilobe can. In other words, if you give me your desirable reciprocating motion profile (realized by a trilobe cam), I can design the relevant single cam lobe profile.

When the outer cam ‘cuts’ the inner cam in twin cam GRECO design, there are no twisting moments on the piston and this is important. Like:
http://www.pattakon.com/tempman/greco_short_stroke.JPG

On the other hand, there is always the solution of single shaft which is lighter, simpler, need not synchronizing gears etc

The thrust roller bearings are not so different compared to the main rollers of Revetec’s and Pattakon’s design. If the thrust bearings do not like the start stop reverse operation, the main bearings do not like the high speed – low speed repeated operation either. Here is the reason:
We start with a revetec/trilobe cam having 100 mm minimum eccentricity and 200 mm maximum eccentricity (i.e. 100 mm piston stroke). At 1600 rpm (of the trilobe cam) the periphery of the main rollers has a maximum velocity of (1600rpm/(60sec/min))*(2*pi*0.2m) =33.5 m/sec, and a minimum velocity of (1600rpm/(60sec/min))*(2*pi*0.1m)= 16.75 m/sec. The maximum velocity happens once per piston reciprocation.

1600 rpm with trilobe cam means 4800 complete piston reciprocations.

Now suppose you take the side loads with thrust rollers identical to the main rollers.

The thrust rollers periphery has a maximum velocity – at the same revs – of 25.13 m/sec (i.e. 2*pi*0.05m*4800rpm/(60sec/min) ) and a minimum velocity zero. The maximum velocity of the thrust rollers happens twice per piston reciprocation.

So the energy to and fro in case of the main rollers is 33.5^2-16.75^2=841.7 energy units, while the energy to and fro in case of the thrust rollers is 25.1^2=630 energy units.
The power to and fro is 841.7 power units in case of the main rollers and 1260 power units (i.e. 2*630) in case of the thrust rollers, i.e. 50% more.

But the thrust loads are far weaker than the main loads, so the thrust rollers can be times lighter than the main rollers.

So, if Revetec achieved to keep the main rollers rolling (and never sliding) on the trilobe cam, the problem of the thrust rollers of GRECO design is already solved.

Thanks
Manolis Pattakos

revetec
10-19-2006, 03:02 PM
Dear santostripoli,

We are involved in an electric hybrid project. This project is in an early stage and I supose that we will release details regarding this relationship in the near future. Thanks for your comments. Our new engine design is very compact which has evolved from our new aviation project. Details of this will be posted on our website early next week.

-----------------------------------------------------------------------------------------

Interesting response Manolis.

This is not an attack. Can I pose some questions and comments for discussion as I'm interested in peoples comments regarding the GRECO engine? You did the same regarding our engine and have been agressive in doing so. Please don't be one sided as you are being very protective of engines you believe in and scathing of others.

The axial twist of the drive shafts in the location I showed previously shows a problem? Shafts must be strong in controlling any axial twisting. Any comments?

The bearings on the guides may be able to handle the load. This is not what I was saying. I said the stop start operation, which will cause wear at the ends of travel. This is where you need the greatest of acuracy on the side load direction change. Too much wear at this point will cause an audible knock. Any comments?

The cam design we are using is of a size that reduces the change of bearing speed over the cam face to a point that is reliable. Do you think that the GRECO engine doesn't require the same type of operation given the application and loading is the same?

When a GRECO single cam engine's main bearings contact the drive cam to induce rotation they must contact at an angle to provide rotation. The side thrust generated from this loading is transfered to the guide bearings which need to handle the load, sometimes it is equal when a 45 degree angle is experienced from the piston bearing load contact. As a rule.... over 30 degrees of deviation from the piston(on a single cam engine) causes too much side thrust and is not desirable due to guiding load handling requirements. Given that 30 degrees is the desireable limit for reliability, the result is a low torque lever similar to a swash plate type of arrangement (great as a driven pump but not a drive motor due to high loading of components). This is why I prefer counter rotation of two or three cams. Any comments in this area anyone?


Manolis: The design you just showed has the piston bearing boss inbedded into the shaft and it is not at BDC yet. The bearings are too small to handle the type of loads from a piston/capacity of that size. The final design will not be as compact as shown and I'm looking forward to seeing how they address this in final designs as it may relate to some components in our engine.

http://i84.photobucket.com/albums/k6/revetec/greco_s_stroke.jpg

The minimum rolling diameter of the cam is far less than our design due to the fact that the roller travels closer to the shaft centre. I have designed our cams with a minimum rolling diameter to achieve reliability of the bearings. and reduce slippage which causes wear. I could do a CAD model which has a smaller cam to make our engine look more compact . If the stroke is the same and the bearing separation is the same distance then the dimensions wouldn't be much different (Slightly larger due to multiple lobes) given the same piston design. But would it be reliable in actual engine testing? I tried this in my first engine ten years ago but wasn't succesful.

Looking into the future of how this engine may be configured for production I performed some basic bearing calculations and refered back to data from our own product plus consulted information from our SKF bearing database.

To make the bearings reliable for consumer products the bearings require to handle full loads at the required top RPM for around 5,000+ hours I searched our database. The only bearings that I found in the marketplace at a reasonable cost for manufacture that I have found are cylindrical roller bearings or oil pressure fed rollers (Maybe a bit hard to do but not impossible).

The bearings must be encapsulated in a case due to the fact that the bearing outer wall is too hard and brittle for this type of application, and have a case wall thickness of approximately 2.5mm. I have tried bearings straight on a cam and they fail due to impact shock causing the outer cases to crack. On calculating the operation application and the encapsulation of the bearings, a bearing selection would lead me to selecting a bearing for roughly the capacity shown of a diameter of no less than two and a 1/2 times the size shown in the models. Does anone know of alternative bearings that can be used as I'm very interested in this area?

The bearings being a lot larger changes the configuration to a point that a production model would not be as compact as the one in the concept design. Any comments?

Please Note: I'm not criticizing the design concept. Just looking at compactness of a production model for my reference.

I do realise that they are just models and they may not be displaying their latest designs.
The basic theory looks OK at this point but I cant see a production model being as compact as shown. I maybe wrong.

A final running engine design will have to be made and tested for reliability, at which point we can compare sizes :-)

We have had 4 complete engine versions running and are designing our 5th series of engines now. Wait till you all see how compact our new engine is! It will be on our website next week!

I'm not going to comment any further on other issues as I've spent 10 years researching roller based piston engines and I don't want to disclose any more information gained from our development program that has come as a great expense to our company.

It's hard to compare a concept engine to an engine that has been developed over 10 years, built an tested. What do other people think of the GRECO engine in design? Is there any other comments out there from anyone on their design/prolems/benefits as it may relate to some components in our project?

Cheers

revetec
10-19-2006, 05:14 PM
Re:Pattakon-PRE

I have seen this type of configuration before. It is better if the combustion process is performed in the middle of the engine to reduce thermal losses. Not a bad design and I have heard there are still a number of these type of configuration engines still on the road such as the Common Knocker.

http://i84.photobucket.com/albums/k6/revetec/common_knocker.jpg
(Common Knocker)

This can be in the Pattakon configuration and use gears to transfer power and time the engine, such as suggested by Manolis.

http://www.pattakon.com/tempman/pre_junkers_clutch.JPG

http://www.pattakon.com/tempman/pre_junkers_supercharged.JPG

So how do you assemble the Pattakon engine? How do you get the crank/counterweights through the piston? Is the shaft in multiple pieces or is the piston split in two parts and which way? If the piston was in two pieces it wouldn't be good to split it through the piston crowns so how is it done? Is the conrod one piece as it would be a bugger to bolt the big end cap together?

The ports are configured like a two stroke engine in the centre so I assume that the combustion is in the centre and it's a two stroke like a common knocker? Is there more detailed pictures out there that explains these questions as I am interested in the construction of this engine?

Cheers

revetec
10-19-2006, 08:20 PM
http://i84.photobucket.com/albums/k6/revetec/pullrodgraph2.jpg

I measured the graphic roughly and worked out it was using a 1.375:1 reverse conrod ratio. Is this graph roughly right? If not right please someone else do it and I'll remove mine.

Comments in regards to breathing and power stroke differences this would cause? A torque lever graph would be useful too...Can anyone do one and post it?

pneumatic
10-19-2006, 09:53 PM
The bearings must be encapsulated in a case due to the fact that the bearing outer wall is too hard and brittle for this type of application, and have a case wall thickness of approximately 2.5mm. I have tried bearings straight on a cam and they fail due to impact shock causing the outer cases to crack.

I and others had picked up running a bearing directly on the lobes would never work and would just result in cracked bearing cases. From the photo's and animations on your website it looked like you were just trying to run deep groove ball bearings (or needle rollers?) directly on the lobes.

The problem is the races are brittle and hard like you say. Due to these properties, the races cannot handle any bending moments / loads. These essentially must be encapsulated so the capsule takes all the bending and contact stress type loads, and the race only ever see compressive loads between the roller and the capsule. This is where you will run into problems. For example, even if you have a rolling element bearing that is a loose fit on the shaft, the inner race will flex enough on that shaft to crack from the resulting fatigue load.

You may want to calculate the contact stresses. This will give an idea if the capsule is thick enough. From the peak contact stress you can also calculate the surface hardness required to prevent pitting of the trilobe / capsule surface.

pneumatic
10-19-2006, 10:00 PM
Note here that the synchronization of the two crankshafts of the PRE engine is not critical and needs not special accuracy, i.e. the PRE will still operate even if you change the phase of the two crankshafts for a few degrees.
And here comes another characteristic / advantage of the PRE : if you deliberately change the phase difference of the two crankshaft more and more, then you have the way to change the compression ratio of the PRE without other complications. If there is interest, I will make some animation to explain the case.

By changing the phase you also change the relationship between the intake and exhaust port timing. But the problem with having them out of phase is vibration.

And added a few gears on looks fine in a concept 3D model, but once you added bearings and other items to support it all then the concept starts to look not so simple.

revetec
10-19-2006, 11:09 PM
Pneumatic:
Your right in your comments. Our animation is just a representation. On our first engine in 1996 we found deep groove bearings to not be suitable. We use cylindrical bearings or solid bushed rollers in our prototypes. Ever since the first prototype we have encased bearings. The material and surface hardening has been the same since. Even though I'm not stating what material we use, the surface hardness or the hardening process, I can tell you that it has not been a problem since. Our software has a calculation base for contact stresses and material selection as well as bearing selection giving us data of bearing life to approximately 1/100 of an hour (Ha ha...well that's what it says although I can't imagine it to be that acurate). The graph was good one for everyone to look at for reference... :-)

pneumatic
10-19-2006, 11:51 PM
Yeah, take some programs with a grain of salt. I use ANSYS for my finite element analysis models, and they are very accurate, but only as accurate as the data that goes in. It calculates contact stresses but I still like to check with a hand calculation just to be sure the FEA is behaving properly.

revetec
10-20-2006, 12:02 AM
We use Solid Edge which is proably the best CAD software for what we do. The Engineers Reference Guide has calculations of just about every mechanical component and SE now has Femap Express which is good FEA for basic checking of components. Other detailed analysis we outsource. We also consult with companies such as SKF if needed.

Cheers
Brad

pneumatic
10-20-2006, 01:06 AM
We have quite a lot of different brands and types of software, but in general I use Solid Edge for the parametric 3D modelling, and export the geometry to ANSYS for analysis. We also use CFX for computational fluid dynamics.

manolis
10-20-2006, 09:40 AM
Brad,


You write:
The axial twist of the drive shafts in the location I showed previously shows a problem? Shafts must be strong in controlling any axial twisting. Any comments?
The U-6 Pattakon GRECO engine you quoted is:
The most compact design I know
It is absolutely balanced (not just as I-6 or V-8 but absolutely as the Wankel rotary engine)
It can use a unique cylinder head, if desirable (like VR-6 of VW)
It can be reduced to a U-4 full balanced - even firing arrangement (removing a pair of cylinders and rotating the cams)
It can turn to a 12 cylinder by just adding six pistons and a cylinder head at the bottom.

If the only problem is the twisting of the drive shafts, all you need to do is to increase the distance of the two drive shafts and the size of the two synchronizing gears. This way you can increase the minimum section of the drive shafts as much as you like.



You write:
The bearings on the guides may be able to handle the load. This is not what I was saying. I said the stop start operation, which will cause wear at the ends of travel. This is where you need the greatest of acuracy on the side load direction change. Too much wear at this point will cause an audible knock. Any comments?
The side rollers begin to decelerate right after the middle of the stroke. I.e. they have plenty of time to completely stop at TDC and then – progressively – to start accelerating at the opposite direction. Then again, after the middle stroke the process repeats. Another way to reduce inertia of the roller is to have the pin on the wall or the cam and the ring on the piston. Such use is shown in the animation http://www.pattakon.com/greco/GrecoSingleCylinderSingleShaftPin.exe.


You write:
The cam design we are using is of a size that reduces the change of bearing speed over the cam face to a point that is reliable. Do you think that the GRECO engine doesn't require the same type of operation given the application and loading is the same?
The only way to reduce the change of bearing speed is by shortening the piston stroke, either in Revetec design or in any other design. In my previous reply I calculate the maximum and minimum speed of the rollers rolling on the cam. Unless I get your writing wrong.


You write:
When a GRECO single cam engine's main bearings contact the drive cam to induce rotation they must contact at an angle to provide rotation. The side thrust generated from this loading is transfered to the guide bearings which need to handle the load, sometimes it is equal when a 45 degree angle is experienced from the piston bearing load contact. As a rule.... over 30 degrees of deviation from the piston(on a single cam engine) causes too much side thrust and is not desirable due to guiding load handling requirements. Given that 30 degrees is the desireable limit for reliability, the result is a low torque lever similar to a swash plate type of arrangement (great as a driven pump but not a drive motor due to high loading of components). This is why I prefer counter rotation of two or three cams. Any comments in this area anyone?
The single lobe cam can be increased in diameter as desirable. In the following plot the three cams are for the same piston stroke.
http://www.pattakon.com/tempman/thrust.GIFIncreasing the size of the single lobe cam, you can get as small thrust loads as you want. It is, as always, a matter of compromise.


You write : Manolis: The design you just showed has the piston bearing boss inbedded into the shaft and it is not at BDC yet. The bearings are too small to handle the type of loads from a piston/capacity of that size. The final design will not be as compact as shown and I'm looking forward to seeing how they address this in final designs as it may relate to some components in our engine.

The rollers are small in diameter but you can use more than three rollers per piston, in parallel (i.e. you can use, as the stroke is too short, three cam lobes in parallel on the one drive shaft and two on the other drive shaft, that is five small rollers in parallel per piston, which distributes the loads on the wide piston directly to the cam lobes making the piston light and nevertheless strong). This way the compactness can remain as shown.


You write:
Looking into the future of how this engine may be configured for production I performed some basic bearing calculations and refered back to data from our own product plus consulted information from our SKF bearing database.

To make the bearings reliable for consumer products the bearings require to handle full loads at the required top RPM for around 5,000+ hours I searched our database. The only bearings that I found in the marketplace at a reasonable cost for manufacture that I have found are cylindrical roller bearings or oil pressure fed rollers (Maybe a bit hard to do but not impossible).
The bearings must be encapsulated in a case due to the fact that the bearing outer wall is too hard and brittle for this type of application, and have a case wall thickness of approximately 2.5mm. I have tried bearings straight on a cam and they fail due to impact shock causing the outer cases to crack. On calculating the operation application and the encapsulation of the bearings, a bearing selection would lead me to selecting a bearing for roughly the capacity shown of a diameter of no less than two and a 1/2 times the size shown in the models. Does anone know of alternative bearings that can be used as I'm very interested in this area?

The bearings being a lot larger changes the configuration to a point that a production model would not be as compact as the one in the concept design. Any comments?



Please Note: I'm not criticizing the design concept. Just looking at compactness of a production model for my reference.

I do realise that they are just models and they may not be displaying their latest designs.
The basic theory looks OK at this point but I cant see a production model being as compact as shown. I maybe wrong.

A final running engine design will have to be made and tested for reliability, at which point we can compare sizes :-)

We have had 4 complete engine versions running and are designing our 5th series of engines now. Wait till you all see how compact our new engine is! It will be on our website next week!

I'm not going to comment any further on other issues as I've spent 10 years researching roller based piston engines and I don't want to disclose any more information gained from our development program that has come as a great expense to our company.

It's hard to compare a concept engine to an engine that has been developed over 10 years, built an tested. What do other people think of the GRECO engine in design? Is there any other comments out there from anyone on their design/prolems/benefits as it may relate to some components in our project?
You know the problems. One of them is the roller bearings reliability. The present state of the art cannot yet guarantee such roller bearings. Maybe tomorrow, and hopefully at an affordable price.
So, it is a matter of new technology.
On the other hand, the PRE engine is based only on yesterday, conventional, tested technology.

Thanks
Manolis Pattakos

manolis
10-20-2006, 09:47 AM
Brad,

You write:
I have seen this type of configuration before. It is better if the combustion process is performed in the middle of the engine to reduce thermal losses. Not a bad design and I have heard there are still a number of these type of configuration engines still on the road such as the Common Knocker.

(Common Knocker)

This can be in the Pattakon configuration and use gears to transfer power and time the engine, such as suggested by Manolis.
In Junkers-PRE, the combustion happens in the middle. Here is the famous, during 2nd world war, Junkers airplane engine:

http://www.pattakon.com/tempman/junkers.JPG

top power concentration and top thermal efficiency (due to the absence of cylinder heads, the through scavenging, the compact combustion chamber etc). The worst is the long distance of the two crankshafts: the required gearing is heavy, expensive and not fault free. Another problem is that it the needs additional scavenging pump.

Pattakon Junkers-PRE is actually a Junkers with short crankshafts’ distance and built in scavenging pumps. More importantly it provides a lot of additional time around TDC, increasing the constant volume portion of combustion thus resulting in improved thermal efficiency and improved power concentration.



You write:
So how do you assemble the Pattakon engine? How do you get the crank/counterweights through the piston? Is the shaft in multiple pieces or is the piston split in two parts and which way? If the piston was in two pieces it wouldn't be good to split it through the piston crowns so how is it done? Is the conrod one piece as it would be a bugger to bolt the big end cap together?
Which one of the PRE arrangements?
Here is a straight four PRE for car engines.
http://www.pattakon.com/pre/PRE.gif

Here is a Junkers-PRE
http://www.pattakon.com/tempman/blueprint.GIFSee also the file www.pattakon.com/pre/blueprint.pdf

In this arrangement, the piston is a single piece.
The crankshaft is single piece too, having a balance web at one side. At crankshaft’s other side the synchronizing gear is cut as the second counter web. The connecting rod is necessarily split as in conventional engines. The block seems reasonable to be in three pieces, a central one comprising the combustion chamber, the intake and exhaust ports and the half of the main crankshaft bearings, while the other two parts comprise the other half of the main crankshaft bearings and the reed valves.
By the way, take a look at one application of the PRE-Junkers engine at www.pattakon.com/fly/Flyer4.exe.

http://www.pattakon.com/tempman/flyers.JPG

Crazy it seems, but who knows.



You write:
The ports are configured like a two stroke engine in the centre so I assume that the combustion is in the centre and it's a two stroke like a common knocker? Is there more detailed pictures out there that explains these questions as I am interested in the construction of this engine?
I see no special difficulties whatsoever in manufacturing or assembling the PRE engine. Take a look at the drawings and the animations in www.pattakon.com/pre/index.html and I will be happy to answer to any specific question.

Thanks
Manolis Pattakos

manolis
10-20-2006, 10:57 AM
http://i84.photobucket.com/albums/k6/revetec/pullrodgraph2.jpg

I measured the graphic roughly and worked out it was using a 1.375:1 reverse conrod ratio. Is this graph roughly right? If not right please someone else do it and I'll remove mine.

Comments in regards to breathing and power stroke differences this would cause? A torque lever graph would be useful too...Can anyone do one and post it?


Brad,

Your plot seems almost right now.
I think it is easier to think about the breathing ‘difficulties’ of the PRE engine not through the piston acceleration plot you use now, but through the piston travel plots.

In the plot below what you see is the piston travel versus the crank angle for a conventional engine, the PattakonPRE (both using conrod to stroke ratio equal to 1.65) and the Harmonic or pure sinusoidal engine.

http://www.pattakon.com/tempman/pre_comp.GIF

If the conventional is revving at 1.35 times SLOWER than the PRE (for instance the conventional is revving at 5600 rpm while the PRE is revving at 7500 rpm), then around TDC the working medium (air or mixture) cannot see any difference. The orange curve in plot below is (around TDC) identical to the blue curve of the PRE.

http://www.pattakon.com/tempman/pre_TDC.GIF

If the conventional is revving at 1,35 times FASTER than the PRE, then around BDC the working medium cannot see any difference again. The orange curve in the plot below is (around BDC) identical to the blue curve of the PRE.

http://www.pattakon.com/tempman/pre_BDC.GIF

So the PRE as regards TDC is nothing but a conventional revving at significantly slower revs, and as regards the BDC, the PRE is nothing but a conventional revving at significantly faster revs.

It is obvious that the valve lift profiles (if valves are used) have to be change to suit to the PRE piston motion, as well as the spark advance (or the injection advance in case of Diesel). If necessary, the PRE can use Pattakon’s Variable Valve Actuation (or VVA) system in order to optimize breathing along the whole rev range (you can see details for this breathing system at http://www.pattakon.com/ ).

In the animation you measured a con-rod to stroke ratio equal to 1.35 but as you understand there is no any limit. As always it is a matter of compromise.

Thanks
Manolis Pattakos

manolis
10-20-2006, 10:59 AM
By changing the phase you also change the relationship between the intake and exhaust port timing. But the problem with having them out of phase is vibration.

And added a few gears on looks fine in a concept 3D model, but once you added bearings and other items to support it all then the concept starts to look not so simple.

Pneumatic

The Junkers-PRE engine is an absolutely balanced engine as regards inertia forces and moments. If in this completely balanced engine the phase of the crankshafts is changed a little, the vibration will still be less than in a conventional having the same number of pistons. The ability of the Junkers-PRE to change the compression ratio is nothing important compared to its rest advantages. It was mentioned as it is in fashion these days and it is easily achieved with PRE.

The synchronizing gears is not a big deal.
Using the PRE for a motorcycle it would be necessary a gear primary transmission. Doesn’t the Yayabusa have a primary transmission with gears? In the PRE this necessary primary transmission is also the synchronization equipment.
So, what is the added complication?

Thanks
Manolis Pattakos

pneumatic
10-20-2006, 04:19 PM
The synchronizing gears is not a big deal.
Using the PRE for a motorcycle it would be necessary a gear primary transmission. Doesn’t the Yayabusa have a primary transmission with gears? In the PRE this necessary primary transmission is also the synchronization equipment.
So, what is the added complication?

It is not a big deal, and can be done. I am just saying by the time you add the supporting bearing and everything the engine isn't as compact as it first looks in the images you posted.

The primary drive between the crank and the clutch basket on a motorcycle engine is relatively compact, because one gear is counterlevered off the crankshaft which is already well supported and stiff. The clutch basket gear is counterlevered off one of the gearbox shafts so it is also already supported and stiff.

I wasn't saying it's hard, I was just saying it's not quite as simple and compact as drawing a few gears on the side.

manolis
10-20-2006, 09:01 PM
It is not a big deal, and can be done. I am just saying by the time you add the supporting bearing and everything the engine isn't as compact as it first looks in the images you posted.

The primary drive between the crank and the clutch basket on a motorcycle engine is relatively compact, because one gear is counterlevered off the crankshaft which is already well supported and stiff. The clutch basket gear is counterlevered off one of the gearbox shafts so it is also already supported and stiff.

I wasn't saying it's hard, I was just saying it's not quite as simple and compact as drawing a few gears on the side.

Pneumatic,
I still try to get the difficulty.
In Junkers-PRE

which is the only PRE that needs synchronizing gears (I hope you saw the rest PRE arrangement animations at http://www.pattakon.com/pre/index.html )
you have an already well supported and stiff crankshaft (as in any conventional motorcycle engine) and a primary gear secured to it (the primary gear could also be cut directly on crankshaft's material).
The Junkers-PRE clutch basket gear is rotatably supported on the block of the engine (it could alternatively be rotatably supported on the gearbox casing too: because Junkers-PRE has a gearbox too).
I can't see any added complication.
Do I miss something?

Yamaha ungrudgingly uses gears and additional counterbalancing shafts in its TDM model just to counterbalance the 1st order inertia forces. And BMW ungrudgingly increases the width of their R motors to get the benefits of the boxer arrangement. I guess Hayabusa, as all big straight four like Honda and Kawasaki - uses one or two second order counterbalancing shafts (and the necessary gearing and bearings) to cancel the second order inertia forces. Just compare their 'simplicity' and their 'balance' to Junkers-PRE.

Thanks
Manolis Pattakos

pneumatic
10-21-2006, 12:34 AM
The outside gears are not a problem. It's the center gear. I have made a sketch to make it more obvious. It won't be very reliable how it is shown in the image below. For that to be possible, the center gear would have to be cantilevered off a single bearing behind the gear (between the gear and the cylinder). This will be very unreliable and/or would lead to a large bearing design. Really it needs a second bearing. You can't set it up like the crankshafts (a bearing either side of the cylinder) because then you'd have a shaft through the combustion chamber. And if you put one in front of the center gear then it can't have a clutch plate in it, because you wouldn't be able to get the clutch plate out.

http://www.offroadvw.net/tech/images/3gears.gif

manolis
10-21-2006, 08:27 PM
Pneumatic,

It is not a problem.

If your argument is correct, i.e. that the center gear does need a pair of bearings at a reasonable distance, then instead of using a shaft penetrating the combustion chamber, it is more simple and functional to move the center gear lower or higher, thereby the supporting ‘necessary’ long shaft with the two bearings to pass outside the combustion chamber. This way the primary shaft of the gearbox can be located lower or higher (whatever seems better) than the crankshaft axes, while the synchronization of the two crankshafts is as good as before. The drawback : a little larger gear diameter.

These in theory, because things are much simpler and easier as you will see in the following.

In my previous reply the Yamaha TDM was mentioned and here is a photo of TDM’s internals.

http://www.pattakon.com/tempman/TDM.JPG

In this photo what makes impression is the ‘complication’.
Count the additional shafts, gears, shock absorbers, bearings and imagine the additional weight, cost, faults and friction. And all these for what? Just to balance the 1st order inertia forces!

In the sane photo one can also see that the clutch basket gear is rotatably supported on a unique bearing (which seems less than 20mm wide). Why so simple? Because the loads it carries do no need something more. If this basket gear had to be used as the center gear in a PRE-Junkers engine, all you need is a projection (like an immovable short shaft) from the center of the block. That simple, compact and robust.


If you still have doubts, just imagine the way a front wheel of a car is rotatably supported to its shaft and then imagine the huge loads – at all directions – the front wheel has to carry.


And regarding bearing loads:

The bearing of the basket gear of a conventional motorcycle is heavily loaded: the force applied to the teeth of the basket gear from the teeth of the crankshaft gear generates:

- a torque that, through the clutch, is transferred to the primary shaft of the gearbox,
- and a force (equal to the force applied to the teeth of the center gear from the crankshaft gear) that heavily loads the bearing(s) of the basket gear.

In the case of the Junkers-PRE the bearing of the center gear remains actually free of loads: the two crankshaft gears apply equal and opposite forces (i.e. a pair of forces) to the center gear (the forces are equal because the two crankshaft share the same instant gas pressure inside the common cylinder), so the center gear’s bearing carries actually nothing. I suppose I could keep the shaft of the center gear of the Junkers-PRE engine by hand.

Thanks
Manolis Pattakos

pneumatic
10-21-2006, 11:52 PM
All I am saying is that it isn't as simple as shown in that image. And it isn't. That is all I am saying.

The motorcycle examples are totally different because you don't have a main component anywhere that is supported by a single cantilevered bearing. The motorcycle clutch basket has the bearing inline with the teeth, but the image above of the PRE-Junker doesn't (as the clutch plate is shown inline with the teeth).

My original quote was "The not so pretty part is connecting the two cranks together to keep them in synch". And it was in regards to the following picture;

http://www.pattakon.com/tempman/fly.JPG

I was just saying that the picture above makes the engine look really really simple. But in reality you need to connect the cranks, which obviously makes the design bulkier. That is all I was saying. I didn't say it was hard to do, or couldn't be done.

manolis
10-22-2006, 06:11 AM
Brad,
here is the plot for the acceleration of the PRE with 1.375 con-rod to stroke ratio

http://www.pattakon.com/tempman/PREacc.GIF

Thanks
Manolis Pattakos

manolis
10-22-2006, 07:09 AM
All I am saying is that it isn't as simple as shown in that image. And it isn't. That is all I am saying.

The motorcycle examples are totally different because you don't have a main component anywhere that is supported by a single cantilevered bearing. The motorcycle clutch basket has the bearing inline with the teeth, but the image above of the PRE-Junker doesn't (as the clutch plate is shown inline with the teeth).

My original quote was "The not so pretty part is connecting the two cranks together to keep them in synch". And it was in regards to the following picture;

I was just saying that the picture above makes the engine look really really simple. But in reality you need to connect the cranks, which obviously makes the design bulkier. That is all I was saying. I didn't say it was hard to do, or couldn't be done.

Pneumatic,

OK, from now on instead of saying 'it is really really simple', we will say 'it is really simple' or just 'it is simple'.

I hope you agree that the center gear of the PRE motorcycle engine (i.e. the PRE13.exe animation) can be rotatably supported on a projection (i.e. an immovable very short pin) at the middle of the block and that this support is very light, really robust and involves no complication.
Sorry if in the animation it is not clear that the teeth of the gears are in the same plane with the bearing of the center gear. But this is 'the' reasonable selection for the location of the bearing, so I supposed it was obvious. I was wrong.
In any case the animations in the pattakon site are made to show, in the international language of pictures, the general idea and not the details.

I would prefer to have your comments on the substance of the PRE idea. Please write your objections.

By the way, take a look at
http://www.pattakon.com/fly/Flyer4.exe
and
http://www.pattakon.com/fly/Flyer5.exe
animations added these days to pattakon site.

Thanks
Manolis Pattakos

pneumatic
10-22-2006, 04:04 PM
Sorry if in the animation it is not clear that the teeth of the gears are in the same plane with the bearing of the center gear. But this is 'the' reasonable selection for the location of the bearing, so I supposed it was obvious. I was wrong.

In the image below, there is a clutch and pressure plate in the middle of the center gear, inline with the teeth. So the "reasonable selection for the location of the bearing" cannot be inline with the gear teeth, because there is a clutch plate there. So it must be cantilevered off a bearing at the back, which would be a bad design.

http://www.offroadvw.net/tech/images/3gears.gif

I know the images are concepts, and because of that they are not worth discussing. It is easy to make a concept, it is hard to figure out all the details and still have a good design.

The Revetec concept is fine, but the details shown thus far haven't been very impressive. It sounds like they are working through the details and making progress, so the final design may still be good, but until then there isn't much point commenting.

Take the flying machine concept. It shows the handle bars out in front of the propellers. That wouldn't work, the handle bars need to be inline with the propellers - which is easy enough to fix.

The concept animations make it look very simple, but when you add all the other bits needed to make it work you realise the actual product would be much much bulkier. For it to be a detailed design, they need to add;
* A fuel tank
* Carb's or EFI
* A starter motor (or starting device)
* a battery
* an alternator / generator (which has to be run off the crankshafts)
* cooling. air cooled fins will make the design much bulkier. water cooling needs a water pump and radiator
* spark plugs, probably 2 (one each side of cylinder)
* ignition system, leads, coil, something to time the spark
* guarding for the fans (as they slow down the machine will want to fall onto the ground unless you are strong enough to hold it up until it stops)

So you can see the animations they show are rather pointless. They only show a very simple concept. It will still have vibrations. Although the pistons balance each other, the conrods will still produce unbalanced vibrations.

To be honest I don't see the point of having the outer piston halfs. Normal two strokes get by just fine using the underside of the firing piston and crankcase to do the same job.

I think a conventional pair of two stroke engines set up so the pistons face each other would probably be better. The advantage of running the two stroke fuel/oil premix through the crankcase is that the premix lubricates the bottom end very well, and cools the piston.

On the PRE-junker the second piston will try to keep the fuel/oil premix out of the crank area. So from what I can gather they are going to use an oil ring and lubricate the crank with engine oil like a 4 stroke engine (advantage is they don't need premix oil). So now you probably need to add an oil sump and oil pump to the list of parts required for the engine. You also have to make sure you don't get too much oil around the cranks, or you will have a lot of power loss due to oil being flung around under the pistons.

So you can see when you start getting into the detail, then the problems with the design will come out.

I am not saying any of it can't be overcome, but I am saying that those animations are deceiving because they make it look really simple.

revetec
10-22-2006, 10:49 PM
Dear Manolis

Your graphs seem to look ok but we have discussed on here previously that a longer conrod ratio is for higher revving engines such as F1. If you look at the graph 1.65:1 is good for 7,000rpm and 2:1 is good for 18,000rpm so what type of characteristics will you get from such a piston acceleration curve?

My point is that an engine running such an acceleration curve must make it only suitable for a lot greater than 18,000rpm? Doesn't it?

revetec
10-22-2006, 10:52 PM
Not really a fan of the way the pistons separate. But I suppose they may come up with alternative designs....

My "bearings" point on the GRECO engine was that if you separate the shafts so they don't hit and the bearings are made at a size that is reliable and those components will not fit up the bore unless the engine is very very oversquare. At that point they'll have trouble getting the piston out the way to open the valves. We'll just have to wait to see how they address it. :-)

revetec
10-22-2006, 10:59 PM
Dear Pneumatic,

I agree with your comments on the bearings on the output shaft of the Pattakon engine. These gears are necessary and it'll be interesting to see how they get it all to work and what the prototype will look like and vary from the concept shown.

I suppose your comments on our engine will be a bit different once our website is updated and our new design is shown. :-)

santostripoli
10-23-2006, 12:24 AM
When will your web site be updated?

What date are you expecting it to be ready so that we can all have an open discussion on the merits of the technology.

Regards
SPT

pneumatic
10-23-2006, 12:30 AM
I suppose your comments on our engine will be a bit different once our website is updated and our new design is shown. :-)

I just hope there's enough info there to figure out what's going on this time :D

manolis
10-23-2006, 01:27 AM
Pneumatic,

You write: In the image below, there is a clutch and pressure plate in the middle of the center gear, inline with the teeth. So the "reasonable selection for the location of the bearing" cannot be inline with the gear teeth, because there is a clutch plate there. So it must be cantilevered off a bearing at the back, which would be a bad design.

This slide is taken from the original CAD file by means of which the PRE13.exe animation was created.

http://www.pattakon.com/tempman/PRE13.GIF

and the following slide is after elevating a little the parts of the clutch

http://www.pattakon.com/tempman/PRE13A.GIF

and here are the detailed support of the center gear (not shown in the animation)

http://www.pattakon.com/tempman/PRE13B.GIF



You write: I know the images are concepts, and because of that they are not worth discussing. It is easy to make a concept, it is hard to figure out all the details and still have a good design.
The Revetec concept is fine, but the details shown thus far haven't been very impressive. It sounds like they are working through the details and making progress, so the final design may still be good, but until then there isn't much point commenting.

If we had the prototype to test, then what the use of asking opinions and critics. We have undergone the same when we asked for opinions and objections about Pattakon’s VVA system. You can’t imagine what the opposition and the snobbery was those days. Now we have the prototype cars ready for anyone to test drive them. And the initial design of VVA was actually the manufacturing design / blueprint (in most details) for all the VVA prototypes. When you get the time, take a look at the video
http://www.pattakon.com/vvar/OnBoard/A1.MOV.

The commenting and criticism of people skilled in the art is worthy only prior to the building of the real thing.



You write: Take the flying machine concept. It shows the handle bars out in front of the propellers. That wouldn't work, the handle bars need to be inline with the propellers - which is easy enough to fix.

If you look at the animations of the flying machine, you will see that there is a hole in the red frame (which comprises also the handle bars) from where – I thought it was obvious – the rider / pilot is hanged from, as in the a parachute or in a parapede, i.e. the rider is hanged exactly as you say, i.e. in line with the two propellers. The handles give the rider the ability to move his body relative to the engine/propellers and so to control his flying machine, just like a rider controls his bike.


You write: The concept animations make it look very simple, but when you add all the other bits needed to make it work you realise the actual product would be much much bulkier. For it to be a detailed design, they need to add;
* A fuel tank
* Carb's or EFI
* A starter motor (or starting device)
* a battery
* an alternator / generator (which has to be run off the crankshafts)
* cooling. air cooled fins will make the design much bulkier. water cooling needs a water pump and radiator
* spark plugs, probably 2 (one each side of cylinder)
* ignition system, leads, coil, something to time the spark
* guarding for the fans (as they slow down the machine will want to fall onto the ground unless you are strong enough to hold it up until it stops)

A fuel tank.
Having an engine of top thermal efficiency (read HONDA’s patents mentioned in my previous replies to Brad. These patents simply start with: ‘in order to increase thermal efficiency by increasing the constant volume portion of combustion it is proposed etc etc’).
It seems that saving, say, one third of the fuel for a specific ride/fly, deserves no discussion.

EFI
I.e. two injectors (for safety reasons) and two spark plugs (in case PRE is not compression ignition), a fuel pump and an EFI unit. How much all these weight? How much weights Hayabusa’s injection and ignition system.

A starter motor
You have the propeller within the reach of your hands to crank the engine, if necessary by both hands. The starter motor is a heavy luxury. Even in small airplanes.

An alternator / generator
Why the alternator cannot be directly driven by the lower end of the one crankshaft? And how much an alternator – with capacity to supply electric power to the EFI unit, to spark plugs (if any) and to a position/safety light – weights?

Cooling
Take a loon at this airplane engine. Through away the cylinder heads with their heavy and long fines – which protect from exhaust valve overheating – and keep only the cylinders with their short and light fins.

http://www.pattakon.com/tempman/Lycoming3.JPG

Overcooling is here the problem, not overheating.

Guarding for the fans
The hope is to have a very light propulsion system. If so, strong or weak riders can keep it in place until propellers stop rotating. A light version for light rider could help (the light rider needs less powerful engine and smaller rotors).


You write: So you can see the animations they show are rather pointless. They only show a very simple concept. It will still have vibrations. Although the pistons balance each other, the conrods will still produce unbalanced vibrations.

Wrong. Analysing properly the con-rod into two masses, the one at the piston pin and the other at the crankpin (both completely balanced as there is another piston making the opposite reciprocation inside the same cylinder) the only that is left is an inertia torque due to the angular acceleration of the con-rod. But again there is another con-rod at the other side of the cylinder producing the same – and opposite – inertia torque. The sum is permanently zero, I.e. if you left the engine run and the rotors rotate, the cylinder / block is absolutely free from vibrations, and this is a must for a portable flying machine.
Use the http://www.pattakon.com/educ/balance.exe program. It may help.


You write: To be honest I don't see the point of having the outer piston halfs. Normal two strokes get by just fine using the underside of the firing piston and crankcase to do the same job.
I think a conventional pair of two stroke engines set up so the pistons face each other would probably be better. The advantage of running the two stroke fuel/oil premix through the crankcase is that the premix lubricates the bottom end very well, and cools the piston.
....
. So now you probably need to add an oil sump and oil pump to the list of parts required for the engine. You also have to make sure you don't get too much oil around the cranks, or you will have a lot of power loss due to oil being flung around under the pistons.

I thought it was a step ahead the two stroke operation with four stroke lubrication. GM with its big Diesels think this way too. In the animations you can see the oil rings, two per piston, which never pass over the intake or exhaust ports. The oiling is as efficient as in the conventional four stroke engine, without oil loss. The piston crowns oil-cooling is as in present state of the art four stroke engines.
Beyond the uncontrolled oiling, the fouling of the plugs, the additional cost of oil, the emissions and the smell, what the premix oiling provides. One of the problems of the Wankel rotary engine is the need for two stroke oiling.
To my thinking, after the thermal efficiency, the best the Junkers-PRE provides is the outside piston crowns. Adding actually nothing, you get the best scavenging pumps I can imagine. They have a minimum dead volume which guarantees a top scavenging at all revs and loads. On the other hand, the large dead volume inside the crankcase is a major problem of the conventional two stroke (anything but flat torque curve).
The pair of the two conventional two stroke you mention, has two cylinder heads to dissipate energy on them, the Junkers PRE has none.
The pair of the conventional two stroke will necessarily use cross scavenging, a far less efficient and far less clean way than the through scavenging of the Junkers PRE engine (take a look at the 2nd world war airplane Junker design in a previous reply). Why to use two crankshafts at a large distance from each other with heavy synchronizing gearing between them? The only difference they make is the through scavenging and the elimination of the cylinder heads.
So yes, an oil sub is necessary – as in all four stroke – and an oil pump at the lower end of the one crankshaft. And the control of the oil quantity at the cylinder is already solved (long ago) in horizontal boxer engines of airplanes (like Lycoming), bikes (like BMW boxers) etc.
Think of Junkers-PRE as a two stroke functioning without the two stroke problems.



You write: I am not saying any of it can't be overcome, but I am saying that those animations are deceiving because they make it look really simple.

Deceiving animation!
For what reason?
A couple of years ago, trying to get thoughts, suggestions and criticism about the Pattakon VVA system, the objection was that ‘putting this system into a Honda B16 and B18 production engines is impossible’. Download the
http://www.pattakon.com/vvar/OnBoard/Assembly.exe collection of photos and think again.

If what you mentioned as problems of the Junkers-PRE are the most serious problems of this propulsion system, my view is that this Pattakon Flying Machine has potential.

Thanks
Manolis Pattakos

pneumatic
10-23-2006, 03:58 AM
Manolis, you need to read my posts and learn to relax. I never said there was anything wrong with any of the design. Everything I have said is true.

The detail of the clutch and pressure plate is too simplified. The pressure plate needs a clamping surface which is not shown. The clutch plate needs friction linings which are not shown. The input shaft that will go through the clutch plate needs a pilot bearing in the flywheel, which there is no room for. A single deep groove ball bearing will not provide enough support for the flywheel. The ball bearings have radial and axial clearances that will be exaggerated by the big diameter of the flywheel, and it won't like the thrust load from the throw-out bearing. Not to mention that the hottest part of the engine (the center) is now covered with a flywheel and bearing support which will make cooling the area more difficult.

You are proving my point that there isn't much point talking about it without all the details, because every time I say something you give a new detail to counter my point.

Everything I said the engine still needed, it still needs. You just don't think the impact of adding those extra parts will be as much as I do. So we have a fundamental difference of opinion. :)

I don't have the time to sit down and calculate your forces in your engine at the moment :( , but from first glance the conrod forces don't look balanced.

I never said your design won't work. I doubt the flying machine will work, as I think you under-estimate the thrust required to lift a person. I think unguarded blades will be dangerous. But they are just my thoughts. I am not the keeper of all knowledge, I am not some expert that you need to gain permission from. If you ask for my thoughts, then accept them when you get them.

I will add that I do like the VVA concept. It is quite interesting. :)

manolis
10-23-2006, 04:18 AM
Dear Manolis

Your graphs seem to look ok but we have discussed on here previously that a longer conrod ratio is for higher revving engines such as F1. If you look at the graph 1.65:1 is good for 7,000rpm and 2:1 is good for 18,000rpm so what type of characteristics will you get from such a piston acceleration curve?

My point is that an engine running such an acceleration curve must make it only suitable for a lot greater than 18,000rpm? Doesn't it?


Brad,

Sorry, it does not.

The piston acceleration data you used (piston acceleration versus crank angle for various con-rod to stroke ratios) were not correct. You wrote “Below 1.5:1 the initial velocity suffers also shown in the plotting of the ratio of 1.2:1 which is too low” and now you know this is far from being true.

As I understand, the connection you make between the piston acceleration and the breathing ability of an engine is not based on some theory, just on intuition. Not enough. If there is a connection between them, I like to know.

Having a specific four stroke PRE engine (i.e. given the con-rod to stroke ratio) I can move the peak torque at my desirable revs (let say 3000 rpm) just selecting properly the valve lift profiles. If I want the peak torque of the same engine to be at 6000 rpm, again I can: by proper selection of the valve lifts profiles (and the rest details that effect the free breathing, like intake manifold etc).
A typical tuner does exactly this work: he takes a normal engine with good torque at low revs and changes the camshafts, the intake manifold, the exhaust etc to finally achieve an engine having peak torque at higher revs and high maximum power at extreme revs, with drawbacks the reliability, the high consumption, the emissions, the poor drivability etc. The con-rod to stroke ratio has, compared to the valve train system, only minor effect on the breathing.

According your writing, a formula1 engine cannot breath well at 2,000 rpm because its con-rod to stroke ratio is too long (2.0 or more). This is absolutely wrong. It cannot breath because the overlap of its valves is selected to give the best at 15000 to 18000 rpm. If you change the camshafts of the formula1 engine with other ones providing no overlap and short lift, the formula1 engine could have a torque peak at – why not – 2,000 rpm. The fact that such engines are extremely over-square will decrease the thermal efficiency.

I.e. breathing is mainly a matter of the valve train system. The power train does have, but only minor, effect on breathing.

I.e. whatever con-rod ratio you choose I can make the engine breath good at your desirable revs.

Thanks
Manolis Pattakos

manolis
10-23-2006, 04:20 AM
Not really a fan of the way the pistons separate. But I suppose they may come up with alternative designs....

My "bearings" point on the GRECO engine was that if you separate the shafts so they don't hit and the bearings are made at a size that is reliable and those components will not fit up the bore unless the engine is very very oversquare. At that point they'll have trouble getting the piston out the way to open the valves. We'll just have to wait to see how they address it. :-)

Brad,

An advantage of the GRECO is exactly that it can, with reasonable height, have a long stroke. Look at the animation of Greco in line three.

I am not sure you got it right what I wrote about the U-6 Greco.
If you want more strong drive shafts, all you need is to increase their distance.
For each mm increase of their distance, the thinner section of each drive shaft increases by exactly the same amount. So an increase of the drive shafts distance by – let say – 15 mm makes them much stronger than necessary in any application.

And as we talk about U-6 drive shafts strength, take into consideration that GRECO’s drive shafts undergoes only the 1/3 of Revetecs three lobes drive shafts torque, for the same pistons and bore (and even less as Revetec’s pistons are necessarily double pistons).

If the only drawback your expertise finds for the GRECO U-6 design is the ‘weakness’ of the drive shafts, U-6 GRECO has potential. Doesn’t it?

Thanks
Manolis Pattakos

manolis
10-23-2006, 06:19 AM
Manolis, you need to read my posts and learn to relax. I never said there was anything wrong with any of the design. Everything I have said is true.

The detail of the clutch and pressure plate is too simplified. The pressure plate needs a clamping surface which is not shown. The clutch plate needs friction linings which are not shown. The input shaft that will go through the clutch plate needs a pilot bearing in the flywheel, which there is no room for. A single deep groove ball bearing will not provide enough support for the flywheel. The ball bearings have radial and axial clearances that will be exaggerated by the big diameter of the flywheel, and it won't like the thrust load from the throw-out bearing. Not to mention that the hottest part of the engine (the center) is now covered with a flywheel and bearing support which will make cooling the area more difficult.

You are proving my point that there isn't much point talking about it without all the details, because every time I say something you give a new detail to counter my point.

Everything I said the engine still needed, it still needs. You just don't think the impact of adding those extra parts will be as much as I do. So we have a fundamental difference of opinion. :)

I don't have the time to sit down and calculate your forces in your engine at the moment :( , but from first glance the conrod forces don't look balanced.

I never said your design won't work. I doubt the flying machine will work, as I think you under-estimate the thrust required to lift a person. I think unguarded blades will be dangerous. But they are just my thoughts. I am not the keeper of all knowledge, I am not some expert that you need to gain permission from. If you ask for my thoughts, then accept them when you get them.

I will add that I do like the VVA concept. It is quite interesting. :)

Pneumatic,

Believe or not, I deeply appreciate your replies.
You are of the few that risk a question about a technical matter.
I do thank you.


The motorcycle Junkers-PRE engine (i.e. PRE13.exe) with the center gear is not necessarily air cooled, so the projection that rotatably supports the center gear does not spoil the cooling.
On the other hand, the Flying Machine (Flyer1.exe) which needs to be air cooled (for lightweight) does not need clutch neither supporting shaft on the middle of the block.


But it seems we cannot agree on matters like the width of the clutch, the type of the roller bearing of the center gear, the weight of the cooling fins etc.
So let us concentrate on a matter of pure mathematics.

I clearly claim that the Junkers-PRE with the opposite rotating crankshafts is absolutely balanced, i.e. on its cylinder-block there are neither inertia forces, nor inertia moments, nor inertia torques of any order (at least as these terms are defined in Taylors books). In a nutshell, there are no inertia vibrations at all.

The Junkers-PRE with the opposite rotating crankshafts (like the one in the Flying Machine) is, with respect to inertia, as balanced as the Wankel rotary engine and a little better than the best V-12.
Furthermore: As long as the load is divided equally to both opposite rotating crankshafts (it is the case of the proposed Pattakon Flying Machine, it is the case of a single cylinder stationary dual electric generator, it is the case of an outboard engine driving two screws etc etc) the block/cylinder is absolutely free – as a whole – from inertia vibrations AND from power vibrations (notice here: a single crankshaft Wankel electric generator suffers from heavy power vibrations).

So the two counter-rotating crankshafts that share the same combustion chamber (i.e. they see the same instant pressure) have advantages in several applications.

The previous are applicable to the typical Junkers engines, too. These engines prevail in thermal efficiency over the single crankshaft conventional engines.

The Junkers-PRE with the long dwell around TDC, further improves the already top thermal efficiency of the typical Junkers engines. And besides Junkers-PRE brings the two crankshafts closer (making the synchronizing gearing shorter-simpler-lighter-quieter and reducing considerably the bending moments on the cylinder block) it also has an excellent built-in scavenging pump.

If I am true, doesn’t Junkers-PRE deserve a little attention?

Thanks
Manolis Pattakos

PS: beleive it or not I prepaired this reply based on your original - not the edited - message.

revetec
10-23-2006, 02:57 PM
As we discussed before about conrod ratios, it does have a marked effect on the operation of an engine. If it didn't, then we would see F1 using shorter conrod ratios such as 1.3:1 to make an engine more compact and save weight. A selection of conrod ratio is made with consideration to operational RPM. I have tried a sine wave cam in one of our engines which is half way between a conventional engine and the Pattakon selections. We needed to supercharge the engine to get it to perform. I know that the Pattakon engine's outer piston supercharge's the centre end of the piston, but the pumping losses of supercharging will probably result in little benefit to overall efficiency when compared to a conventional engine with no supercharger. I'll be interested in the final design and look forward to seeing results once a Pattakon engine is built and tested.

There is plenty of ways to design and make an engine. I have seen many designs that look ok from a CAD model, but many fail in prototyping due to unforseen problems. I think this discussionis taken the wrong way! All we are doing is discussing possible points of failures of the project. Healthy discussion only results in good information and/or opinions that might spur on further thoughts and innovation that will help your cause. In our early development many people put in their opinions which helped me with further thoughts on which way the development program should be headed. Knowing all the possible faults with a product helps you design a better product.

Please note: If it isn't cheaper to produce, doesn't require too much retooling to manufacture, fit most existing applications layouts ( size / weight /c onfiguration / Rev range / peak power and torque RPMs, fit transmissions ), cheaper to run, more reliable than what we already have and marketable to the general public, then it's a big upward battle.

These days emissions and efficiency of conventional engines is pretty optimised. It takes a lot more research and development these days to reach a level that will be accepted by any engine manufacturing company(Usually 5-10% better). This means that an initial engine will just be an evaluation engine because no one can be expected to get it right the first time. Usually the forth version engine is getting it almost right. Costs vary from $300,000 to $1.5 million for each of any serious engine prototype. With each prototype, the design varies greatly due to innovation with the technology and feedback from testing advances and failures.

I'll be watching the Pattakon engine in the future to see how they travel.

revetec
10-23-2006, 03:03 PM
Oh...Here is a little help.... The centre drive shaft... lower it to below the cylinders (you can still gear the cranks to it) and you can run a shaft under the combustion chamber and get the shaft long enough to be supported well. See a good free tip for you, which has resulted from healthly discussion on this forum.

revetec
10-23-2006, 03:10 PM
My IT guy says our website update will be in two days. :-)
I will post the link when it's up and running.

pneumatic
10-23-2006, 05:25 PM
Ok, I will make more comments. But they are just my thoughts at this stage.

I don't think the PRE-Junker engine will ever be useful for a car or motorcycle, as it is too wide for it's capacity. It is simply the wrong geometry to be practical.

I don't think air cooling will work with this layout, because the gears are in the way of the air flow.
http://www.pattakon.com/fly/img4.jpg

You'd either need some complex shrouding, or to move the gears to the lower side.

I actually don't think air cooling will work at all, because as the center part of the cylinder thermally expands, the crankshafts move further apart and the gears will lose their mesh. I think Junker had a similar problem in his earlier engines.

I think you need a more rigid outer casing with water cooling to keep the expansion under control. Or you need a rigid case to run around the cylinders to the crankshafts, and let the cylinders grow in towards each other. Or you need to get rid of the gear connection and use a chain / belt with a tensioner. There are lots of options, but they all effect the size and practicality of the final design.

Having opposing pistons gave thermodynamic advantages back in the 30's, but I don't think the advantage is as significant these days. There are better ways to reduce thermal losses through the cylinder head, like ceramic coatings and even ceramic engine parts. Ceramic coatings on piston crowns, combustion chambers and valves are very common performance modifications.

I think the one-way valves will be troublesome and difficult to to control. If they don't close in time they will hit the piston. Reed valves on a normal two stroke can stay open at high rpm with no problem.

The "exhaust" side (not a very good name, but you should know what I mean) will pose problems. There is no room in the port for it to open. It needs a space to fold back into.

What will the one-way valves be made from, and how will they have a spring force applied?

Starting the device by the propellor will be hard. Since there is no guard, you can't sit it in the ground and crank it over. You need to hold the entire machine over your head with one hand, and crank it over by the propellor (which is probably out of reach) with your free hand.

As for efficiency, two-stroke petrol engines are not as efficient as two-stroke diesels. In a two stroke you get good power when you get to the point that some of the intake charge completely flushing the combustion chamber and starts to go into the exhaust (before the compression stroke). On a diesel engine this is fine because a diesel is direct injection, and only injects the fuel it needs. Therefore by wasting intake charge out the exhaust you only waste air, not fuel.

If you inject fuel (petrol) into the intake port, then losing intake charge out the exhaust is inefficient. If you use direct injection petrol you still need to figure out how much air is in the combustion chamber to inject the correct mixture of fuel. It is hard to do if some goes out the exhaust.

So two-stroke intake/exhaust timing and efficiency generally only go together in diesel engines. A diesel would be too heavy for the flyer.

Some interesting info on the junker;

The Junkers aircraft 2-stroke diesels comprised 6 in-line vertical cylinders, 12 pistons and 2 crankshafts coupled by a gear train, also used for the propeller reduction gear. The lower pistons opened the intake ports, the upper ones opening the exhaust ports. In order to get the optimum timing, the lower (intake) crankshaft was about 11° retarded relative to the upper exhaust one. So the latter received roughly 3/4 of the power and it was geared directly to the propeller shaft.

I'm sure retarding it 11degrees didn't do much for the balancing either.

kingofthering
10-23-2006, 05:31 PM
hmmm. with an engine like this, it would be possible to create a scooter with the power of a motorcycle.

manolis
10-24-2006, 02:15 AM
Brad,


You write: As we discussed before about conrod ratios, it does have a marked effect on the operation of an engine. If it didn't, then we would see F1 using shorter conrod ratios such as 1.3:1 to make an engine more compact and save weight. A selection of conrod ratio is made with consideration to operational RPM.

The typical formula1 engine has, as they say, a piston stroke of about 40 mm.
If the piston pin is 20 mm in diameter, the piston pin bosses have to be at least 30 mm in diameter. The crankshaft webs need to be less than
2*(conrod length – 0.5*(piston stroke)- radius of piston bosses),
i.e. 90 mm in diameter when the conrod to stroke ratio is 2 (i.e. con-rod center to center distance equals to 80mm). If the conrod ratio decreases to 1.5 (i.e. con-rod length decreases to 60 mm) the diameter of the crankshaft webs decreases to 50 only mm otherwise the crank hits the piston. I suppose their main crankshaft journals are near 50 mm in diameter.

I.e. the use of less than 2.0 con-rod to stroke ratio in such over-square engines is impossible spatially

Looking from another point of view, the 40 mm stroke means – for 2500 cc 8 cylinder capacity – a bore of 100 mm.
Most formula engines are in V-90 arrangement.
Take a crankpin of the crankshaft and connect two con-rods of 60 mm (center to center) at a 20 mm offset (i.e. the wirth of the con-rod) each one having one piston of 100 mm bore at their other ends.
When the pistons are close to their BDC, their piston skirts hit each other.
If this is confusing, take a look at the

http://www.pattakon.com/pre/PRE3.exe animation.

I.e. in formua1 the a con-rod to stroke ratio of around 1.5 is not possible, neither it offers more compact design or less weight.
I.e. the 2.0 or more con-rod to stroke ratio is not a choice, it is a necessity.



You write: I have tried a sine wave cam in one of our engines which is half way between a conventional engine and the Pattakon selections. We needed to supercharge the engine to get it to perform. I know that the Pattakon engine's outer piston supercharge's the centre end of the piston, but the pumping losses of supercharging will probably result in little benefit to overall efficiency when compared to a conventional engine with no supercharger. I'll be interested in the final design and look forward to seeing results once a Pattakon engine is built and tested.

How did you optimise the breathing of the harmonic revetec engine?
How many valve lift profiles (i.e. how many different camshafts) did you use to find the optimum camlobes?
I you had a pattakon VVA system on the cylinder head (like the one on the Pattakon Civic prototype) then you could easily optimise the breathing of your harmonic VVA at your desirable revs.
Optimising the breathing of an engine by manufacturing and replacing camshafts is nothing but a nightmare.

I.e. keeping ‘some’ camshafts (which are optimised for other than harmonic piston travel profile) and expecting the harmonic to breath well, is not correct.

I.e. the Pattakon PRE, which is not necessarily of Junkers-PRE design (take a look at the four stroke PRE versions) does not need supercharging to breath well. With the VVA as the tool, the optimisation of the breathing is a relatively simple and a really low cost procedure. When the final optimum valve lift profile is reached, the relevant valve lift profile is recorder and the correct cam shafts are designed.

Thanks
Manolis Pattakos

manolis
10-24-2006, 02:23 AM
Pneumatic


You write: I don't think the PRE-Junker engine will ever be useful for a car or motorcycle, as it is too wide for it's capacity. It is simply the wrong geometry to be practical.

A 500cc Junkers-PRE engine (50+50=100mm stroke, 80mm bore) has a maximum dimension of 557 mm

http://www.pattakon.com/tempman/blueprint.GIF

The power and the torque of this engine are close to those of a conventional 1000 cc four stroke.
I measured the width of the Honda Civic VTEC engine. This engine has at its top a width of about 530 mm (670 with the distributor). This engine has also a depth of about 240 mm and a height of about 540 mm (if you can please please let me know the Hayabusa’s engine dimension).

In case of twin Junkers-PRE (i.e. two cylinders sharing the same crankshafts (having crankpin at 180 degrees for even firing) the maximum dimension of the Junkers-PRE remains at 557 mm while it becomes 1000 two stroke cc in capacity. I.e. more powerful and more smooth than the civic 1600 straight four. The rest dimensions of the Junkers-PRE are beyond comparison.

The compactness and the external form of the Junkers-PRE are advantages not drawbacks.

Compare the Junkers-PRE 500 cc with BMW’s Boxers 800 cc or 1000cc: the one is like the mother of the other, in all dimensions. In case of Junkers-PRE the engine could be mounted on a motorcycle even longitudinally as a part of the frame (this for Kingofthering).



You write: I don't think air cooling will work with this layout, because the gears are in the way of the air flow.

You'd either need some complex shrouding, or to move the gears to the lower side.

I actually don't think air cooling will work at all, because as the center part of the cylinder thermally expands, the crankshafts move further apart and the gears will lose their mesh. I think Junker had a similar problem in his earlier engines.

I think you need a more rigid outer casing with water cooling to keep the expansion under control. Or you need a rigid case to run around the cylinders to the crankshafts, and let the cylinders grow in towards each other. Or you need to get rid of the gear connection and use a chain / belt with a tensioner. There are lots of options, but they all effect the size and practicality of the final design.

The synchronizing gears is preferable at the top, close to the rotors. The four stroke lubrication helps here: the gearing case has oil that can cool the cylinder below as necessary. Many Suzuki aircooled motorcycle engines use the air-oil cooling.

As for the thermal expansion:
The thermal expansion was a problem for the typical Junkers PRE because the distance of the two crankshafts was huge compared to Junkers PRE. The typical Junkers long gearing had also to carry half of the power to the output shaft. The gearing of Junkers-PRE carries no power.
On the other hand, The synchronizing gears in the plot above are not in line. If you keep their centers at constant distance, no matter how much the distance of the crankshaft enlarges, their operation remains correct. But this is luxury.


You write : Having opposing pistons gave thermodynamic advantages back in the 30's, but I don't think the advantage is as significant these days. There are better ways to reduce thermal losses through the cylinder head, like ceramic coatings and even ceramic engine parts. Ceramic coatings on piston crowns, combustion chambers and valves are very common performance modifications.

I hear about adiabatic engine for some twenty years now. If they succeed, the Junkers-PRE will also take advantage of them. Today they are not in use despite the vast amounts of money that have been spend on this technology. Their investors know.



You write: I think the one-way valves will be troublesome and difficult to to control. If they don't close in time they will hit the piston. Reed valves on a normal two stroke can stay open at high rpm with no problem.

What will the one-way valves be made from, and how will they have a spring force applied?

The existing reed valves of the two stroke motorcycles are more than adequate for the Junkers-PRE as they operate reliably over 15,000 rpm.
By the way take a look at some other kind one way valves at

http://www.pattakon.com/vva/VVA_Idle/VVA_Idle.htm


You write: The "exhaust" side (not a very good name, but you should know what I mean) will pose problems. There is no room in the port for it to open. It needs a space to fold back into.

Sorry, be more specific. I don’t understand.



You write: Starting the device by the propellor will be hard. Since there is no guard, you can't sit it in the ground and crank it over. You need to hold the entire machine over your head with one hand, and crank it over by the propellor (which is probably out of reach) with your free hand.

OK, here is a problem. Maybe something like a kick starter.


You write: As for efficiency, two-stroke petrol engines are not as efficient as two-stroke diesels. In a two stroke you get good power when you get to the point that some of the intake charge completely flushing the combustion chamber and starts to go into the exhaust (before the compression stroke). On a diesel engine this is fine because a diesel is direct injection, and only injects the fuel it needs. Therefore by wasting intake charge out the exhaust you only waste air, not fuel.

If you inject fuel (petrol) into the intake port, then losing intake charge out the exhaust is inefficient. If you use direct injection petrol you still need to figure out how much air is in the combustion chamber to inject the correct mixture of fuel. It is hard to do if some goes out the exhaust.

So two-stroke intake/exhaust timing and efficiency generally only go together in diesel engines. A diesel would be too heavy for the flyer.

What we actually think is to use in the flying machine Diesel Junkers-PRE for the sake of fuel economy. I hear you saying ‘but the additional weight’. If the fuel weight can be reduced more than 3 Kp, the take off weight will be less than using petrol. Junkers-PRE can operate at lower compression than normal Diesels because of the dwell at TDC.
If it was the typical Junkers, the Diesel cycle would have a marked increase on engine’s weight. In case of the Junker-PRE the two close to each other crankshafts make the bending moments on the cylinder weaker etc etc. So all you need is a reinforced cylinder and two stronger crankshafts.

If direct petrol injection is used, the lambda sensor gives the feedback to the EFI and the injection duration is adjusted as in the present car. When the Pattakon Civic prototype uses ‘closed loop’ control, it automatically reads the Oxygen concentration at exhaust and adjust the injection duration.


You write: Some interesting info on the junker;
Quote:
The Junkers aircraft 2-stroke diesels comprised 6 in-line vertical cylinders, 12 pistons and 2 crankshafts coupled by a gear train, also used for the propeller reduction gear. The lower pistons opened the intake ports, the upper ones opening the exhaust ports. In order to get the optimum timing, the lower (intake) crankshaft was about 11° retarded relative to the upper exhaust one. So the latter received roughly 3/4 of the power and it was geared directly to the propeller shaft.

I'm sure retarding it 11degrees didn't do much for the balancing either.

If the absolute balance is necessary, the asymmetric timing is not the case. If necessary, a clap at exhaust can offer the control.
If the asymmetric timing is advantageous a little vibrations is the price.
In the flying machine it is better to have Diesel cycle with absolute balance.

Thanks
Manolis Pattakos

pneumatic
10-24-2006, 03:32 AM
A 500cc Junkers-PRE engine (50+50=100mm stroke, 80mm bore) has a maximum dimension of 557 mm. ..... .... The power and the torque of this engine are close to those of a conventional 1000 cc four stroke.

A 500cc two stroke is not equivalent to a 1000c four stroke. That used to be a rule of thumb, and they used it for sizing the new capacity when motogp went from 500cc two-strokes to 1000cc four strokes. They were getting around 200HP from the two strokes, and 250HP from the four strokes which aren't tuned as hard. A 500cc two stroke is closer to a 800cc four stroke in practice (my observations).

You shouldn't say the maximum dimension is 557mm, because in reality it won't be. That sketch shows no material thickness on the ports or anything. It reality it will be a bit longer, how much longer depends on how everything will be detailed. But your right it can be made to fit in a car, but I don't think it's shape is practical and would be used in a car (just my opinion).


In case of twin Junkers-PRE (i.e. two cylinders sharing the same crankshafts (having crankpin at 180 degrees for even firing) the maximum dimension of the Junkers-PRE remains at 557 mm while it becomes 1000 two stroke cc in capacity. I.e. more powerful and more smooth than the civic 1600 straight four. The rest dimensions of the Junkers-PRE are beyond comparison.

Compare the Junkers-PRE 500 cc with BMW’s Boxers 800 cc or 1000cc: the one is like the mother of the other, in all dimensions. In case of Junkers-PRE the engine could be mounted on a motorcycle even longitudinally as a part of the frame (this for Kingofthering).

As I mentioned before, I think a 1000cc twin junkers-pre will only be comparable with a 1600cc engine power wise anyway. You are correct, you could lay it across the frame like a BMW boxer, but I don't think that's a good layout for a bike. That's why no other manufacturer does it. BMW do it because it's their trade-mark (and they are doing it less and less, introducing more conventional engines all the time).

I think the biggest problem for car or motorcycle use is that it is a 2-stroke. So it either needs to compete with a convential 2-stroke, or show a lot of advantages over a 4-stroke.

People buy two-stroke motorcycles because of their outright performance and light weight. A J-PRE engine will be bigger than a conventional 2-stroke, and won't make a significally different amount of power to offset the size and increase in complexity.

And these days two-strokes are being phased out. Why - because 4-strokes are more efficient, have more than ample power and require less maintenance. The extra complexity and extra weight / size is not a problem. And, they have a more user-friendly power band.

This is the big question mark over the J-PRE that no-one can answer until one is built. What will the power delivery be like? Will it be like a traditional 2-stroke?

I think in the end this engine would have to compete with another "alternative" engine design, offering similar size and power advantages. That engine is the Rotary (Wankel). The wankel has never been widely accepted despite it's size and power for size.


The synchronizing gears is preferable at the top, close to the rotors. The four stroke lubrication helps here: the gearing case has oil that can cool the cylinder below as necessary. Many Suzuki aircooled motorcycle engines use the air-oil cooling.

yes many motorcycles use oil / air cooling, but they still have fins for some air cooling. And if it uses oil cooling then it needs an oil cooler. So if you use oil cooling in the flyer then you need to add an oil cooler to the list of parts.


The gearing of Junkers-PRE carries no power.

If the J-PRE is used for a motorcycle or car, then it will transmit 50% power like the junker.

In the flyer it will transmit whatever power you have drawn off one of the cranks to drive the ancillaries of the engine (oil pump, alternator, etc).


On the other hand, The synchronizing gears in the plot above are not in line. If you keep their centers at constant distance, no matter how much the distance of the crankshaft enlarges, their operation remains correct. But this is luxury.

I don't know what you mean by "are not in line". They look in line. If the crank case heats up and grows, then the distance between the crank centres will grow and meshing will be a problem.


The existing reed valves of the two stroke motorcycles are more than adequate for the Junkers-PRE as they operate reliably over 15,000 rpm.

Have you seen existing reed valves? They won't fit in the space you have allocated. Reed valves have steel plates that are permanently in the "open reed valve" position. So you can't have the reed valves opening into the cylinder, as then the steel limit plates would be hit by the piston.



You write: The "exhaust" side (not a very good name, but you should know what I mean) will pose problems. There is no room in the port for it to open. It needs a space to fold back into.

Sorry, be more specific. I don’t understand.

If the exhaust reed or valve is oval like the port, then it cannot swing open on a pin. It simply won't open. The port needs a recess for the reed to open into. Draw it in 3D and you will see what I mean.

And if you change to traditional reeds, then you won't get the "zero volume" at TDC on the outer pistons. It will also make the engine a little bigger in width too. Again, this area needs to be detailed to see what problems will arise.


OK, here is a problem. Maybe something like a kick starter.

I think it needs a start motor and battery. Manual starting is not marketable.

revetec
10-24-2006, 03:41 PM
Our REVETEC website has been updated!

The link to our Latest News page for the X4 is: http://www.revetec.com/?q=engine-dev

http://i84.photobucket.com/albums/k6/revetec/RLX407.gif
Four cylinders drive two cams. Output shaft is the lower shaft providing two strokes of each piston per 360 degrees of rotation (Same as a conventional and our previous engine).

Pistons are inline and balance out 2/3's of each other's weight. Top balance shafts balance out the other 1/3 (up and down movement).

Most downforce applied to and lost into a conventional engine's main journal is deflected into the opposing cam gaining more rotational force. Torque lever is extended throughout the stroke which transfers torque more effectively. As the point of peak presure moves up and down the stroke due to RPM, Load and fuel mixtures, the transfer is always kept at a higher amount than a conventional engine.

http://i84.photobucket.com/albums/k6/revetec/X4mark4-opt.jpg
2.4 litre X4 engine; currently being designed (Shown without cylinder heads)
International patents on the X4 engine have been lodged.

Block is only 160mm front to back (2.4 litre) and is about 40% the size of most equivalent engines being currently manufactured.

Cheers

pneumatic
10-24-2006, 04:31 PM
http://i84.photobucket.com/albums/k6/revetec/RLX408-small.gif
{from website}It was found that the cylinders could be arranged in a 60 degree X configuration using only two trilobe cams.

That's pretty cool :D. Using two cams for 4 pistons should be able to offer weight and space saving.

I can see the engine will offer the space and weight saving, but I am still not so sure about the magnitude of the efficiency advantages. Some of the efficiency gain of the trilobe vs crankshaft design will be lost by the need to gear the output shaft down, and also run the 2nd trilobe through two gears to make it spin the other way. We could talk theory until the cows come home, but test data will be the final word. :)

It will be interesting to see how noisy those gears are too, and if you need to go to helical gears (less efficient but quieter). Motorcycles use straight cut gears which do make a lot of whining noises, but motorcyclists love the mechanical noises so it is ok. The aircraft and trike guys probably won't care either, but car manufacturers and buyers might.


The power and the torque of this engine are close to those of a conventional 1000 cc four stroke.

Manolis, just one more thing on this subject. Yes a 2 stroke will make more power and torque than an equivalent sized four stroke, but in the real world the differences aren't so big.

Have you ridden many motorcycles before? Try riding a 250cc 2-stroke and a 250cc 4-stroke. The 2-stroke will ultimately be faster, but the 4-stroke is easier to ride around on, with a more gentle and easy to use power delivery.

Therefore just because a 1000cc two-stroke is enough to move a car as fast as a 2000cc (or 1600cc maybe) four-stroke, it doesn't mean it will be as nice or easy to drive.

There are a lot of factors that decide whether an engine is successful, and outright power and torque is only a small part. Manufacturers could make all engines very very powerful, but they don't. They want an engine to be smooth (power delivery and vibration wise), quiet, have good fuel efficiency, long service life, and a whole heap of other factors. A lot of these factors you will not know until you run a proto-type. The Junker-PRE might show advantages in all of these areas, it might not.

Trucks are a good example. Some trucks want a cheap light powerful and relatively efficient engine (workhorse type trucks), so they go for a supercharged 2-stroke diesel (which has oil in the crank area like the Junker-PRE). It meets that manufacturers criteria, but the engine is harsh and noisy.

Another manufacturer might want efficiency with refinement and quiet operation (more expensive long haul trucks), so they go for a turbo-diesel four stroke engine.

So the question is, what engine will the Junker-PRE compete with? I think it will need to compete with a supercharge diesel.

A supercharged diesel uses a positive displacement blower to do the 2-stroke scavenging. The Junker-PRE uses the outer pistons and some one way valves to do the same thing. I think a screw-type positive displacement blower would probably do the same job more efficiently, so I don't think the Junker-PRE will successfully compete with the tried and proven supercharged 2-stroke designs.

And since no-one uses supercharged 2-strokes in cars or motorcycles, I don't think anyone would want to use a Junker-PRE either.

revetec
10-24-2006, 04:46 PM
Pneumatic: We have used helical and spur gears previously. Nothing in the geartrain has changed in layout or design. We have not experienced any gear noise since our last gearset design and the efficiency losses through the geartrain are marginal compared with our gains.

Cheers

pneumatic
10-24-2006, 05:10 PM
Ok. I had noticed spur and helical combination on the previous engines.

The only difficulty with that engine in a car is the center of gravity and engine height is quite high compared to the centreline of the output shaft.

So to take advantage of the engine shape you would really need a custom transmission with a low input shaft, and then run a small diameter multi-plate clutch flywheel combo?

Do you have any plans for this area?

revetec
10-24-2006, 06:29 PM
The height is not a problem. The engine is actually shorter than conventional inline engines. The engine is only 470mm from the top of the engine to bottom of sump. Output shaft to bottom of sump is about a standard distance :-)

pneumatic
10-24-2006, 06:46 PM
Ok, you must have a real deep relatively empty sump like a Subaru :D

When people stick the Subaru motors into VW's or rally cars they cut anything up to 85-100mm out of the sumps. :eek:

I think they have such a deep sump to stop the oil sloshing around behind the horizontal pistons when the car is cornering hard, or even when the car is parked on a side angle. VW's (older flat 4 VW's) have shallower sumps, after you park them on a side angle and then start them up they blow smoke (because the sump oil actually spills into behind the piston and seeps past the rings while the car is parked).

The X4 Revetec might notice a similar thing on the bottom 2 pistons, but not from sump oil, just the small amount in the cylinder at the time (which won't be much). I doubt it will be noticeable.

revetec
10-24-2006, 06:56 PM
We are using total seal rings so any oil will be pushed back to sump from the cylinders on cranking. This engine is for an aircraft so it requires a deep sump. We have got this engine so compact....I'm very happy with it.
Cheers :-)

Revetec Latest News...the X4 (http://www.revetec.com/?q=engine-dev)

santostripoli
10-24-2006, 07:18 PM
Pneumatic

You make references to the packaging effeciencies of the engine in addition to its weight reduction and note that you can not see the mechanical effeciencies. This is obvious, given that we have not been given test results.

However, even if the engine is capable of offering the same power and torque as per a conventional engine, the X4 is still far more superior due to its weight advantage (power to weight ratio) in addition to its compactness; this all makes the X4 concept quite remarkable.

In todays day of age of making things smaller and weigh less this is a positive step.

If what Brad is saying is correct (whcih he will prove some time soon with official test results), this engine will offer
(1) torque and power delivery advanatges
(2) power to weight advantage
(3) packaging effeciencies

It ticks all the boxes for a new age engine.

Well done Brad, just keep us all up to date on the engine stats so that we can sit comfortable and watch this engine concept show its true merits.

Regards
Santos

manolis
10-24-2006, 08:19 PM
A 500cc two stroke is not equivalent to a 1000c four stroke. That used to be a rule of thumb, and they used it for sizing the new capacity when motogp went from 500cc two-strokes to 1000cc four strokes. They were getting around 200HP from the two strokes, and 250HP from the four strokes which aren't tuned as hard. A 500cc two stroke is closer to a 800cc four stroke in practice (my observations).

......

If the exhaust reed or valve is oval like the port, then it cannot swing open on a pin. It simply won't open. The port needs a recess for the reed to open into. Draw it in 3D and you will see what I mean.

And if you change to traditional reeds, then you won't get the "zero volume" at TDC on the outer pistons. It will also make the engine a little bigger in width too. Again, this area needs to be detailed to see what problems will arise.



I think it needs a start motor and battery. Manual starting is not marketable.


Pneumatic,

The cover of the ‘scavenging pumps’ is so thin because the pressure is very low. A blade of 2.5 to 3 mm thick is more than necessary. Onto this blade there are the ‘holes’ than form, with additional thin blades like razors, the one way valves. These thin blades will be taken by reed valves of conventional two stroke motors, i.e. from the reed valves of a motorcycle only the blades will be used not the case.
There are countless ways to make a one way valve of very short height and still streamlined. Normally the one way valve blades shown in the Flyer1.exe animation have to be nailed at one side on the scavenging pump cover plate, being at their ‘restore’ or ‘idle’ position closed (their own material is the restoring spring). This way the dead volume can be as small as desirable.


’500 cc two stroke is comparable to 800 cc four stroke’ is not a bad relation for the Junkers-PRE, given the four stroke lubrication and reliability of the Junker-PRE, the lightweight, the absence of cylinder heads etc.
But the ‘four stroke like’ lubrication, the built-in scavenging pumps with the minimized dead volume, the through scavenging, the reduced thermal loss and friction at the eliminated cylinder heads and the increased thermal efficiency due to slow piston motion during high pressure make me think the 1000cc Junker-PRE can make more than the 2000cc four stroke.
The bad reputation of the conventional two stroke is because the disadvantages the PRE comes to eliminate.
Yes, practice has to show whether the theory about PRE and Junkers-PRE is wrong. A prototype Junkers-PRE has to be made.
The usefulness of the discussion is to reject the project in the case something looks wrong in the first place. For instance, if Brad’s argument that ‘a long con-rod engine can never breath efficiently’ was correct, the four stroke PRE had to be rejected. If premixed lubrication was necessary in the Junkers-PRE, again this version of PRE had also to be rejected too. If PRE’s thermal efficiency was theoretically less than four stroke, again PRE project had to be rejected. Etc. Until now neither theory, nor experience can kill PRE’s idea. Future will show.
A hopeful thing about PRE is that it needs no new technology to be manufactured. What I mean is that we cannot make rollers for the GRECO crankless engine. If the conventional rollers are not good enough for such an application, forget GRECO. But we can use the piston rings of the Honda Civic VTEC as the piston rings of the Junkers-PRE. Or the blades from two stroke reed valves as the one way valves of the PRE. Etc. ETC. So a PRE engine could be built and operate into days without having hidden problems to be solved: I know a well equipped machine shop can built it in a few days, not in weeks.


Wankel has specific disadvantages that were never cured:
The extreme consumption caused by the attenuated combustion chamber which leaves no chance for acceptable thermal efficiency (the last model of Wankel in RX-8 consumes 1.2 l/hour at idling, a great step ahead compared to the 1.6 l/hour of the previous model RX-7 but still more than double compared to the typical engines)
the piston/rotor pressure ‘rings’ leakage
the two stroke lubrication
the thermal and cold regions on the engine walls


With the alternator at the lower end of one crankshaft and the oil pump at the lower end of the other crankshaft, the imbalance of power on the two crankshaft is not worthy to mention.


Take a look at the last plot I sent to this forum, not at the animation. In the plot the centers of the four synchronizing gears form something like Z, not like I. Keeping each one of the three pairs of intermeshing gears (i.e. the two left, the two middle and the two right) in constant distance, the mechanism is not affected by the change of the distance of the two crankshafts. But such complication is more than necessary. The small distance of the two crankshaft keeps the absolute thermal expansion acceptable.
As for the starter, it is a luxury. To make easier the starting and the take-off for the rider, a pillar (column) on the ground can be used to secure, to check and to start (manually) the Flying Machine. Then the rider is secured to the Flying Machine and leaves the ground and the pillar.

Thanks
Manolis Pattakos

revetec
10-24-2006, 09:01 PM
Pneumatic

You make references to the packaging effeciencies of the engine in addition to its weight reduction and note that you can not see the mechanical effeciencies. This is obvious, given that we have not been given test results.

We have given the results in the power/torque graph posted. We are producing almost the same torque as the Hayabusa engine at about half the RPMs which greatly saves fuel. Everone did notice that didn't they?



However, even if the engine is capable of offering the same power and torque as per a conventional engine, the X4 is still far more superior due to its weight advantage (power to weight ratio) in addition to its compactness; this all makes the X4 concept quite remarkable.

In todays day of age of making things smaller and weigh less this is a positive step.

If what Brad is saying is correct (whcih he will prove some time soon with official test results), this engine will offer
(1) torque and power delivery advanatges
(2) power to weight advantage
(3) packaging effeciencies

It ticks all the boxes for a new age engine.

Well done Brad, just keep us all up to date on the engine stats so that we can sit comfortable and watch this engine concept show its true merits.

Regards
Santos

Thanks Santos :-)

revetec
10-24-2006, 09:25 PM
Manolis:

I don't know much about flying aircraft but I imagine that this flying machine would need to operate similar to a helicopter. You need to pitch the blades in a twin rotor helicopter in any direction to manuvre around. This makes things more complex...especially the controls on such an idea.

Plus with this design...If it stops you'll die.

Far better to strap an engine to your back with a parachute.

It's definitely one thing I wont be having a go of.

pneumatic
10-24-2006, 09:56 PM
We have given the results in the power/torque graph posted.

Which power/torque graph was that, and which engine was it from?

The only graph I saw didn't seem to be comparing apples with apples. :confused:

Manolis, Rotaries do not use two-stroke lubrication, and have perfectly reliable apex seals these days. :)

I didn't follow what you were saying about adapting reed valves. Perhaps you will need to draw a diagram.

revetec
10-24-2006, 10:13 PM
This one... Which is correct because it is running 2 strokes of the piston per 360 degrees of rotation of the output shaft.

Remember that these are two vastly different engines. Our one was setup for automotive use. But we were still delivering more power at our test RPMs. Higher revving engines will come in the future but currently they are not our target market.

http://i84.photobucket.com/albums/k6/revetec/busa_vs_revetec.gif

We are producing almost the same peak torque as the Hayabusa engine at about half the RPMs which greatly saves fuel. Everone did notice that didn't they?

http://i84.photobucket.com/albums/k6/revetec/RLX407.gif

pneumatic
10-24-2006, 11:07 PM
You can't compare those two, they are like chalk and cheese. I used that graph to show that you can't compare an engine that is essentially internally geared. That was when the revetec information was saying 6 strokes per 360 crank revolution, that is why I made that comparison, because if the revetec was doing that many strokes than it was compariable in piston and valve train speed to a hayabusa.

But as has been said, all that Revetec info has been superseded, so the discussion was no longer valid.

All that graph shows is the hayabusa is a far more high performance motor making huge amounts more power.

The Revetec needs to be compared to something of a similar state of tune. With the info available at the time that appeared to be a Hayabusa, but apparently it isn't.

revetec
10-24-2006, 11:18 PM
I'll post some target market comparisons when I have time :-)

santostripoli
10-24-2006, 11:18 PM
Pneumatic, one tick though, if the Revetec engine produces a significant torque value at a lower rpm, what does it matter what enegine it is compared to? Whether it is compared to a Hayabusa or a jet engine, the Revetec engine produces a high amount of torque and does so with an engine that weighs less and is smaller.

I have stated in the past that I am not an engineer, I have an interest in cars. My interpretation of this Revetec engine is that it has similar characteristics to a diesel engine (in the sense that it has low down torque) however unlike Diesel it can run on unleaded petrol therefore making it cleaner and friendlier to the environment.

Brad, you said you may have some results by Xmas, so for now all we have is the table that charts the power and torque of your prototype engine that was NOT developed for performance, just a proof of concept.

Pneumatic, do you not agree that the torque figure is somewhat impressive?

pneumatic
10-24-2006, 11:55 PM
Pneumatic, one tick though, if the Revetec engine produces a significant torque value at a lower rpm, what does it matter what enegine it is compared to?

Yes it does matter. A lot of people don't understand horsepower and torque, and what it all means.

Where an engine makes it's peak torque is dependant on how it is tuned. If it is tuned for high performance it makes it's torque high in the rev range. If it is tuned for reliability and drivability then it makes the torque much lower.

The higher you can keep making the torque in the rev range, the more power you get.

The engine size and efficiency effects the torque. And as far as peak torque goes, the Hayabusa makes more (and it is a smaller motor).

You see there is a negative to making torque low in the rev range, and that is that you need to select a taller gear to run at the same speed. And torque is effected by gear ratio's, therefore the issue gets confused.

santostripoli
10-25-2006, 12:20 AM
Pneuamtic said:
Where an engine makes it's peak torque is dependant on how it is tuned. If it is tuned for high performance it makes it's torque high in the rev range. If it is tuned for reliability and drivability then it makes the torque much lower.

Response & Question
Brad said that his engine is tuned for an aircraft application, not automotive. He has tuned this engine to deliver torque low in teh rev range. This equates to good fuel economy.

Pneuamtic said:
The engine size and efficiency effects the torque. And as far as peak torque goes, the Hayabusa makes more.

Response & Question
Brad's engine has not been designed for peak torque, it is designed for economy. Therefore Revetec engine is more effecient becuase its torque is reached at an earlier RPM.


Pneuamtic said:
You see there is a negative to making torque low in the rev range, and that is that you need to select a taller gear to run at the same speed. And torque is effected by gear ratio's, therefore the issue gets confused.

Response & Question
How do diesel engines deal with thsi problem then? They have torque low in the rev range yet they manage to get away with it doent they. But they dont do it with an engine that weights less and is smaller in size.


Now, I am looking at this as a casual observer reading the facts and Pneumatic based on what you have said I cant really see your point?

Brad, what is your response on this?

Regards

Santos

pneumatic
10-25-2006, 12:42 AM
I just thought I would copy this edit over from the previous page;

The Revetec announcement with the dyno curve in it (4 May 2006) compares a Revetec RHL4 with a Toyota Prius, which is not fair as the Prius is a very low performance high efficiency hybrid car. The Prius is 57kW and 115Nm from a 1.5L. Compare this to an Opal 1.4L engine which has 66kW and 125Nm. There is a big variation in conventional engines, so comparing the Revetec to them will be difficult.

Any comparisons need to be fair comparisons, they must both be tested to the same international standard. This will dictate what ancillarys are on the engine at the time (if you have no alternator or water pump on one engine, it will make more power because no power will be lost to those ancillaries). I don't know if the Revetec has a water pump or alternator on it at the time of the test. I am sure Brad will let us know :)

revetec
10-25-2006, 12:45 AM
You are right.

We design engines to suit a certain application which is automotive which usually has a rev range up to 6,000rpm.
Trucks are heavier and have engines that have a lower RPM range (Diesel) so they run closer ratio gears and in the larger types of trucks, more gears.

Have you noticed a trend in automotive transmissions that we are seeing more and more gear ratios? Some automotive companies are now supplying 6 and 7 speed transmissions to lower the operating rev ranges to save fuel.

So having such a wide rev range is not so important anymore.

Our production model will see further gains. We are shooting at a launch engine with around 30% increase in power and torque compared with comparable featured engines. We can then look at variable valve timing and intakes etc to better address the performance markets. Also note that no development was done on breathing at the stage those figures were produced. Power in the top end rev range will increase in our next engine.

pneumatic
10-25-2006, 12:45 AM
How do diesel engines deal with thsi problem then? They have torque low in the rev range yet they manage to get away with it doent they. But they dont do it with an engine that weights less and is smaller in size.


Most of what you said proves my point. You can't compare chalk and cheese.

The Revetec test engine did not look set-up for aircraft use at all. I am pretty sure it was aimed at the automotive market.

I will explain the diesel analogy later. It will take some diagrams I think :D

pneumatic
10-25-2006, 12:46 AM
Have you noticed a trend in automotive transmissions that we are seeing more and more gear ratios? Some automotive companies are now supplying 6 and 7 speed transmissions to lower the operating rev ranges to save fuel.


I think that is also marketing driven, people like to say they have a "6-speed" for wank value. :D

revetec
10-25-2006, 01:10 AM
I think that is also marketing driven, people like to say they have a "6-speed" for wank value. :D

Look...I have joined this forum so I can let you all know some information that was misinterpreted on this thread. I supose there are people who think we are innovative and the results show we are getting there. Some people will always be argumentative and suffer from tall poppie sindrome. Just accept that our project has merits, our new design is good and compact, we have a major automotive company interested which is impossible to do if you can't prove there will be gains in fuel efficiency.

We are working hard to complete our pre-production prototype and we look forward to showing it off to the world when completed.

We can chat for years about engines. Our technology has nothing to do with an engines top end or breathing. If you ever get the opportunity to actually turn one of our engines by hand you will feel the efficient transfer/torque lever and be totally sold, like everyone that has done it.

Cheers :-)

BTW. JP8, CNG and Diesel versions are coming.

manolis
10-25-2006, 03:41 AM
Pneumatic,

The current Wankel Mazda motor – the most advanced rotary engine ever – needs oil inside the combustion chamber otherwise the ‘rings’ of the rotor/piston fail. This oil is lost at the exhaust. Mazda recommends one check of the oil every two fill up of the fuel tank. And there is an alarm light for low level of lubricating oil.
So the Wankel rotary engine does has two stroke lubrication.



Brad,

The control of the Pattakon Flying machine is already mentioned and it doesn’t need any complication like pitching the rotors. The body of the rider/pilot is more than adequate, just like a rider drives his bike.
As for safety: that is why the moving parts (say cylinder heads, camshafts, timing belts etc etc) have been eliminated in Junkers-PRE engine.
In any case a light safety parachute is always an option.
An engine to your back and a parachute cannot go fast, cannot go long, and you are always at the merci of any gust of wind.



Santostripoli,

Both the torque and the power are important quantities.
Think simply:
As long as you drive into the town traffic, what you really need is torque at low revs. This makes you life easier and less costly.
But when you want to accelerate fast, what you need is plenty of torque at high revs i.e. you need as much power as possible (power is nothing but the torque en engine provides times the revs).
So the good engine is the one having plenty of torque at a wide band of revs, i.e. plenty of torque at low, medium and high revs. If it has good behavior at partial loads too, so much the better.



Brand,

You made already a few essential mistakes in your previous replies. Read your replies once more and you will see you learned a few things through the present discussion. Therefore don’t blame Pneumatic for ‘tall poppie syndrome’.
The hope is that tomorrow we will have more ‘Pneumatics’ to give us tips and judgments and ‘a fresh view point’, for free.

Thanks
Manolis Pattakos

pneumatic
10-25-2006, 04:50 AM
Pneumatic: How about comparing our engine to the current Mazda 1.4litre. And please note that we are improving with every modification. Currently we are 20% better in peak power and torque up to 4,500rpm than Mazda's production engine.

Brad,

I am hoping you have made an honest mistake, or I am reading something wrong, because this a something quite fundamental.

It's just that the image you have posted above looks a lot like what you get if you get a Mazda 2 CHASSIS dyno curve, a lot like this one;
http://www.offroadvw.net/images/mazda2.jpg

And then take the Revetec RHL4 ENGINE dyno curve (from Revetec website);
http://www.offroadvw.net/images/rle4.jpg

and put the two together.

This would be a silly thing to do, because as you know you cannot compare engine power (measured with an engine dyno) with wheel power (measured with a chassis dyno), because wheel power is the engine power less the transmission losses.

Now most dyno operators will work on a number somewhere around 17% for the transmission losses. So that number is basically the same as the 20% gain you are claiming for the Revetec.

You are not comparing apples to apples. If you put your engine in a vehicle, and got a chassis dyno reading, it would be close to that of the Mazda 2.

I am being totally realistic in this thread. I am being pessimistic because if I came on here and was an optimistic we'd all just be saying how great things will be. I am attempting to be some sort of reality check.

I am keeping an open mind, I do like the X4, but there still isn't any good test data to discuss at this stage. When you provide some positive test results, I will be the first to congratulate you.

Manolis,

Ok, I thought you meant the rotary uses a pre-mix with the fuel like a 2-stroke. The consumption of engine oil is very minimal. A normal 4-stroke consumes engine oil too, it is needed to stay in the cylinder wall to lubricate the piston skirt and rings. It also lubricates the valve guides.

Santostripoli,

A diesel is not used because it makes good torque at low rpm, it is used because the diesel is a naturally efficient engine (mostly due to the very high compression ratio it runs). The low rpm is a side effect of the bulky engine design required to handle the high compression, and the time needed to properly combust the injected diesel. European car manufacturers are working out how to use new injection technologies and develop relatively high revving diesels, combining the good efficiency of the diesel with the ability to produce good torque over a very big rpm range (like a petrol engine).

There is an article on the web I will try to find, that discussing power and torque in detail. It asks if you'd rather an engine that makes 100Nm at 2000rpm or 100Nm at 4000rpm (or similar). Basically the 100Nm at 4000rpm is much better as it is twice the power. The second engine can run gearing twice as low to achieve the same speeds, and this means it will actually have twice as much torque at the wheels at a given speed.

Making torque at low rpm isn't the (only) key to good fuel economy.

revetec
10-25-2006, 04:17 PM
Dear Pneumatic: That was an honest mistake...Sorry!

You stated 17% losses but that's for a rear wheel drive car. In a front wheel drive car, the losses are more like 12-15%.

On our next engine we will get a further 10% initially and after testing and mods we expect up to 20% gain. Car manufacturers are happy with a 5-10% increase so it is all good.

Pneumatic: Sorry again....I don't really have enough time to read the whole websites I visit....but I should. I wont post so often so I can verify everything I post from now on. :-)

revetec
10-25-2006, 04:30 PM
It's also hard to get comparison figures as most engine tests are performed in vehicles. Most Chasis Dyno manufacturers and operators factor in 20% drivetrain losses which overstates engine flywheel power and torque. Many major automotive manufacturers have been caught out doing this and overstating engine power. There are new standards world wide coming into effect soon which should help to address this issue.

Every car has different drivetrain losses so to properly check the losses, the engine must be removed and tested on an engine dyno then installed into the vehicle and compare those figures. Not many people remove a standard engine to perform a dyno test so it is hard to get acurate data to compare.

As well as this the two engines must have exactly the same test conditions so should really be performed at the same facility at the same ambient temperature, humidity, fuel quality, fuel temperature etc.

Usually all this information is not released with dyno graphs so how can it all be compared acurately.

Might I also state that when those graphs were produced that the lambda was set at a static 14.7:1. We didn't have time to enrichen and fully program the injection and timing because the engine was packed up and sent OS. I'm looking forward to getting that engine back so I can play with it a bit more.

pneumatic
10-25-2006, 04:44 PM
Dear Pneumatic: That was an honest mistake...Sorry!

You stated 17% losses but that's for a rear wheel drive car. In a front wheel drive car, the losses are more like 12-15%.

Ok. I won't debate the transmission loss issue, as that is a whole different discussion that is regularly argued :) You only know if you do a dyno run on an engine, put it in a car and then redo the dyno run. This is rarely performed.

The problem you will have is finding an actual engine dyno curve for a 1.4L engine. Again, you need to be running the same ancillaries for the comparison to be fair.

There is certainly nothing wrong with the current torque figure of the Revetec, but I also don't see it as out of the ordinary either (yet).

I do find it a little strange that the test engine is apparently having trouble breathing at the higher rpm, considering it is using the cylinder heads and intake manifold from a 2L subaru motor that flows enough air to make over 160kW in turbo form, and 112kW @ 6800 in naturally aspirated form. :confused:

pneumatic
10-25-2006, 04:47 PM
lol, we did the last posts at the same time as each other. It's good to see we said the same thing about dynos and the difficulty of finding good data. :D

I've heard a lot of the manufacturers are understating power now, to be on the safe side and ensure the customer gets what they expect. But who knows what is really going on...:confused:

revetec
10-25-2006, 05:12 PM
lol...we are thinking alike on some topics.
Back to the torque discussion:
If Engine A produces 200 pounds-feet of torque at 2,000 RPM, and Engine B produces 200 pounds-feet of torque at 5,000 RPM, Engine A will have more towing or hauling capability at lower speeds, because it reaches its maximum torque at the lower RPM. Engine B will have more towing or hauling capability at higher speeds, because it reaches its maximum torque at the higher RPM.
But the higher the RPM, the more fuel is consumed. Generally torque is important from an acceleration off the mark point of view. The heavier the vehicle or load, the more benificial higher torque at low RPMs.

If you look at the top end of scenarios like F1, you have to rev the engine at 15,000-18,000rpm to get the vehicle off the mark and not bog down or stall. In the lower end, a truck can accelerated well from just above idle. Higher torque at lower RPM's on the same capacity engines saves fuel. What is preferable is holding that high torque over a wide RPM range to give good performance right through the desired rev range. But most engines that have high torque at lower rpms usually have poor torque or are unable to operate at high RPMs such as a large truck engine. As a result many large truck engine have far more gear ratios in the transmission to deal with the narrow torque band.

revetec
10-25-2006, 05:18 PM
Hey! Even though I made a mistake with the graph, I didn't delete the post...where the hell did that disappear to?

So let's look at what type of driving that torque is all important.
My view from driving my car is Towing, Accelerating from a cruise situation and/or driving at a constant speed and then going up a hill. (higher torque mostly results in not having to select a lower gear)

Both situations are around 2,000-2,500rpm.

Anyone have any other thoughts on this?

pneumatic
10-25-2006, 09:07 PM
Ok, to explain the whole torque and horsepower thing will take quite a while, and a lot of examples and graphs to prove. Unfortunately I don't have time to do this just yet. So until then here is some light reading for those interested. It is a good discussion on the subject;

http://vettenet.org/torquehp.html

There are countless other discussions out there.

A good engine has a big area under the torque-rpm curve. You need lots of torque, and you need to be able to maintain that over the rpm range of each gear. The higher the rpm you can maintain that torque, the better (as it gives more power).

The engine that makes good torque down low will be fine for towing. But try to overtake and you will find you can't rev the engine, so need to change up a gear. This drops the torque at the wheels and you will accelerate slower in the next gear. An engine with good torque at high rpm will be able to keep revving out in that gear, not needing to change up a gear, and therefore being much faster.

The thing you need to remember is that just because an engine can make good torque at high rpm, doesn't mean it doesn't make good torque at low rpm. However an engine that makes good torque at low rpm doesn't make good torque at high rpm.

Just because you have an engine that makes torque at low rpm, doesn't mean it will be more fuel efficient at low rpm than an engine that makes it's peak torque at high rpm. The engine with the torque at high rpm may have good fuel economy down low, and up high. However an engine with torque at low rpm cannot have good economy at high rpm.

Confusing? :D

One engine may be as efficient at 3,000rpm as another engine is at 2,000rpm. This gives the 3,000rpm engine the advantage as it can be geared lower. You see in order to get good efficiency from the vehicle, you'd gear it so you cruise at the most efficient rpm. One car would cruise at 3,000rpm, the other at 2,000rpm. Both getting the same efficiency.

But the engine that can cruise efficiently at 3,000rpm would be better. If both engines made say 100Nm of torque at their cruising rpm, the 3,000rpm engine would actually have 150% more torque at the wheels than the 2,000rpm engine (as it would be geared 150% lower).

If you weren't confused before you probably are now :D

santostripoli
10-26-2006, 12:06 AM
Isnt the issue here FUEL ECONOMY not performance orientation?

So from a fuel economy perspective, are we better having torque down low or up high???

pneumatic
10-26-2006, 12:21 AM
One engine may be as efficient at 3,000rpm as another engine is at 2,000rpm. This gives the 3,000rpm engine the advantage as it can be geared lower. You see in order to get good efficiency from the vehicle, you'd gear it so you cruise at the most efficient rpm. One car would cruise at 3,000rpm, the other at 2,000rpm. Both getting the same efficiency.

But the engine that can cruise efficiently at 3,000rpm would be better. If both engines made say 100Nm of torque at their cruising rpm, the 3,000rpm engine would actually have 150% more torque at the wheels than the 2,000rpm engine (as it would be geared 150% lower).

When I was talking efficiency above, I was talking fuel efficiency. Try looking up brake specific fuel consumption. Engines have an efficiency point (curve/map really). Some engines have it low in the rev range, some have it higher in the rev range. If you cruise at a rpm lower or higher than the optimum, then you will use more fuel. So just because you are doing lower rpm doesn't mean you will be using less fuel. The rpm can be too low.

So there is no rule of thumb that says having the torque higher or lower is the best for fuel economy.

revetec
10-26-2006, 12:28 AM
(as it would be geared 150% lower)
But in a sense the 3,000rpm engine would be like driving in third gear compared to the 2,000rpm engine in forth gear?

Pneumatic: yes it would have more torque at hand as you said at the roughly the same throttle opening.

But my experience of driving a car for almost 28 years, if I was to drive down the freeway in forth gear at 100kph and did a fuel consumption test and then did it in third gear it would use more fuel. If I was to do this the throttle would not be open quite as far but not 33% less. And let's assume we are driving a vehicle with a reasonably flat torque curve.

This is all good discussion but does it relate hand in hand with engine efficiency?

An engine does have a point where it is most fuel efficient, but if it is at 2,000rpm and another engine is more efficient at 1,000rpm higher say 3,000rpm with the same capacity etc, your throttle is slightly more closed in the case of third gear but not 33% less. If they produce the same torque at their individual fuel efficiency optimum points then the 3,000rpm engine would have to be alot more efficient to have the same outcome in overall fuel consumption when driven similarly wouldn't it?

This is all confusing but I know in real driving that when you drive down the freeway at 100kph in third gear you use more fuel than in forth gear, no matter how much torque you have at hand and where the peak is. In actual driving, as long as you have a good flat torque curve, it all comes back to good torque at a lower RPM is better for fuel economy doesn't it?

I agree with your comments on driving with a too low RPM. It is not good for overall fuel efficiency to operate an engine too far below the point when an engine has low torque and low efficiency, but let's assume that we're not doing this.

Did all that make sense? :-) Hopefully you get my drift.

revetec
10-26-2006, 01:22 AM
BTW. Everyone is so concerned with peak power and torque when most of the driving occurs at a lower RPM range and at part throttle, and we normally look for good fuel economy especially on the freeway. :rolleyes:

It would be good for car manufacturers to show power and torque figures at cruise or normal driving such as from say...10-30% throttle opening. This would give someone an idea of the engine's characteristics when driven normally.

I know this is a personal preference but I would much rather drive a vehicle with higher torque at a lower RPM because it is nicer to drive. I know there are many rev heads out there that like to give an engine a hard rev and I like to do it once and a while. But we are not looking for good fuel economy when we do this. When fuel efficiency is a concern then you don't hit the throttle as hard and you don't rev the ring out of it. Most people don't like to thrash their engine in day to day driving. Also higher RPM = more wear.

That's why I drive a 5.7 litre Caprice.....No old fart jokes please...I do enjoy a squirt of the throttle now and then. :-)

How many people operate their vehicle with their engine speed at the point of peak power and torque say 4,500rpm and 5,500rpm most of the time at full throttle when driving? I would probably imaging that you would operate your vehicle at these points less than 5% of the total time you drive wouldn't you? I am refering to an average driver, not an 18yo or race car driver ok?

pneumatic
10-26-2006, 04:35 AM
That's why I drive a 5.7 litre Caprice.....

That is the reason why your perspective is somewhat distorted. A big V8 is more efficient at low rpm, they are torque monsters :D

I drive a 1968 VW Baja, with a 1992 Mazda MX6 quad cam V6 in the back (I built it myself). It makes peak torque at about 5500rpm, peak power at 6500rpm and revs to 8000rpm. Now it is a high performance motor that revs very hard, but it's also very very torquey. It's torque curve is relative flat from 2000rpm to 6000rpm. I drive it offroad and it will happily crawl around at 500rpm (seriously!). I put a custom 4th in it so it cruises on the highway at about 2250rpm to get good economy. So just because an engine is revvy and produces torque at high rpm, doesn't mean it can't produce sufficient torque at lower rpms to move the car along and get good low rpm efficiency.

Besides, not all engines are the same. Not all engines like cruising around at 2000rpm (or less). Most small (and efficient) cars are designed to cruise at highway speeds at around the 3000rpm mark. They wouldn't accelerate and would get bad economy at 2000rpm. Just like your V8 will get bad economy revving at 3000rpm, past it's efficiency point. My motorcycle is designed to cruise at 4,500rpm on the highway, this gets good economy and is how it's designed to run.

So what I am saying is that where the peak torque is has absolutely nothing to do with how fuel economic the engine is or will be, or even at what rpm it will be most fuel economic.

The throttle opening can also not be compared in the way you are talking about. If it takes 30HP to push a car through the air and travel at 100kph, then it takes 30HP no matter what gear your in (ignoring the different mechanical losses). Think of the throttle butterfly as a flow orifice. 20% throttle opening might relate to flowing 30HP worth of air. This will be the same for any gear. The problem is you need to take into account the higher mechanical losses (inertia related) at higher rpm, and also the effect of the manifold vacuum changing (which changes the volume of air flow for a certain restriction size). So basically the relationship between throttle opening required to maintain speed and rpm the engine is at is quite complicated and not a simple relationship. It isn't simple enough to make the kind of comparisons that you were thinking about. :)

manolis
10-26-2006, 04:38 AM
The image below is made from some results and plots created by “Pattakon RoadLoad DOS program”.

It is for a two stroke Kawasaki 125cc and for a RHL4 Revetec propelling a typical family car.

http://www.pattakon.com/tempman/roadload.GIF

To download the Pattakon RoadLoad program, create a folder in your computer and save there the files you see in the
http://www.pattakon.com/educ/roadload folder.
With this program it is easy to find, among others, the best gearbox ratios, the revs of best gear shift, the expected best possible performance etc etc.


Kawasaki 125 has plenty of torque (compared to its capacity) at extreme revs. But if you leave the revs of maximum torque, it is ‘chaos’.

Beyond the maximum torque and beyond the revs at which the maximum torque is provided, the distribution of the torque is also – if not more – important. Furthermore, the torque curves at partial loads (partial load response) greatly affect the drivability of the vehicle (the typical torque and power curves are with the throttle valve wide open, i.e. 100% of the load).

The fuel consumption is not directly related to low revs peak torque, as many comparative drive tests show. I.e. things are more complicated than just saying “low revs torque guarantees low consumption”.

The best is to have an engine with flat torque (and good response at partial loads) along a wide range of revs, from let say 800 to 10,000 rpm.
The max-min ratio 10.000/800 gives a good idea for the drivability of the vehicle.
A calculation of the max-min ratio of the engines of this discussion would be interesting.

Thanks
Manolis Pattakos

revetec
10-26-2006, 03:14 PM
This theory all looks and sounds good but......

I drove my car last night showing the instantaneous fuel usage on my trip computer. I picked the rpm band that the torque of my engine is in it's flatest point. I maintained 100kph in fourth gear and the trip meter said 11.9 litres per 100kph. I then put it in third gear and travelled the same stretch of road and maintained the same road speed and the fuel consumption was reading 12.8 litres per 100kph.

Maintaining the same speed in the same vehicle would make you assume that the same work was being done so the power usage would be similar, with a 2% variation from the extra transimission losses. Wind and rolling resistances are the same. That's a 5% fuel saving in 4th gear.

Can anyone else do this with their vehicle and post results?

Comments for?: I was consulting with a chassis dyno specialist and he said that if a factor of 12-15% transmission losses are to be factored in for a front wheel drive car then the test must be carried out in third gear. If you use a 1:1 ratio (usualy forth gear) as many dyno testers use, then the transmission has no gearing losses as such. There are final drive losses which are a constant and there are of course is losses from driving all the transmission shafts around. Any comments on this subject as I'm interested if any have you experienced tests and whether they were carried out in 3rd or 4th gears?

pneumatic
10-26-2006, 05:19 PM
With this program it is easy to find, among others, the best gearbox ratios, the revs of best gear shift, the expected best possible performance etc etc.

My Excel program does exactly the same thing, but is a bit easier to use (DOS programs aren't very user friendly :) ).


The fuel consumption is not directly related to low revs peak torque, as many comparative drive tests show. I.e. things are more complicated than just saying “low revs torque guarantees low consumption”.

That is exactly what I was saying! :)


Maintaining the same speed in the same vehicle would make you assume that the same work was being done so the power usage would be similar, with a 2% variation from the extra transimission losses. Wind and rolling resistances are the same. That's a 5% fuel saving in 4th gear.

Can anyone else do this with their vehicle and post results?

Brad, as I said above, you are only looking at your engine which has it's most efficient point low in the rev range. So of course if you operate it above the most efficient point it will use more fuel. But you have to understand not all engines are big lazy V8's. Most small fuel efficient cars will need to sit closer to the 3000rpm mark to be the most efficient.

But as I and Manolis have said, the point where a car makes peak torque doesn't necessarily equate to the point where it is most fuel efficient. Your car is the perfect example. A 5.7L Holden Caprice makes peak torque at about 4800rpm!!! :eek: I am sure your engine wouldn't be very fuel efficient at that rpm. ;)

So basically the torque curve of the revetec isn't saying anything about whether it will be more fuel efficient than another engine with it's peak torque at higher rpm.

You cannot say that just because the revetec has torque low in the rev range, that it will get good economy.


If you use a 1:1 ratio (usualy forth gear) as many dyno testers use, then the transmission has no gearing losses as such..... ....Any comments on this subject as I'm interested if any have you experienced tests and whether they were carried out in 3rd or 4th gears?

I think your dyno operator is getting confused by some transmissions (only some rear wheel drives I think) that have an exact 1:1 gear that actually locks the input shaft and output shaft together (bypassing the countershaft and not running though any gears in the gearbox itself). So this makes a perfectly efficient gearbox, but it still has to go through the diff (which is inefficient).

For those that are interested, there are two basic types of dyno's, inertial and load types. Inertial are usually the cheapest and are more prone to the effects of gear selection, because each gear multiplies the drivetrain inertia differently (a square of the ratio).

A dyno dynamics dyno is a load type dyno and is more accurate. The company has also made what they call "shoot-out" mode. They have made it as an industry standard method of testing HP, so no matter which dyno you test the car on you get the same results (or so they say).

The load type dyno is still effected by drivetrain inertia but not as badly. The operator will enter the vehicles drivetrain inertia from a standard list of vehicles, however if the drivetrain or engine is modified the figure will be slightly out. This can lead to a small difference in HP figures between gears.

Some gears are also slightly different in efficiency than others. Generally the lower gears like 1st and 2nd are coarse teeth gears for strength, and the higher gears have finer teeth for efficiency and quieter operation.

So dyno guys will dyno the car in the highest gear possible, without exceeding the max roller speed. The max roller speed on most dynos is between 200-250kph, so third gear on most cars is normally used. Using low gears means you notice the effect of the drive train inertia quite a lot, but it also means you have more chance of wheelspin on the rollers.

A gear set only has a certain efficiency for transmitting the power. Spur gears are the most efficient (but cars don't use them because they are noisy, but race cars do use them because they want the efficiency). Most cars have helical gears. These produce a thrust load which is inefficient is wastes power.

You do notice a difference between front wheel drive and rear wheel drives. This is because most rear wheel drives have hypoid diff ring and pinion gears. These are very inefficient, but quite strong. Front wheel drives just have another helical gear which is more efficient that the hypoid.

revetec
10-26-2006, 06:35 PM
I know that front engined/rear wheel drive cars have a 1:1 gear ratio, usually 4th in a manual and 3rd in a 4 speed auto.
Front wheel drive cars usually don't. You're right by saying hypoid are not as efficient as helical, and spur gears are even more efficient. I know that your VW baja doesn't have a 1:1 ratio in any gear either.

Gear ratios and efficiencies change with each vehicle and it also changes with load, so all this shows that a chassis dyno is just a guide unless you know exactly what the drive train losses are under all conditions.

revetec
10-26-2006, 06:58 PM
http://i84.photobucket.com/albums/k6/revetec/gearratios.jpg

I will try and get some FWD & 4WD ratios....

pneumatic
10-26-2006, 07:41 PM
Just be careful, that table above may be a little misleading.

Just because a gearbox has a 1:1 ratio doesn't mean it is the type of 1:1 ratio that locks the input shaft and output shaft together (to get the good efficiency).

The VW transaxle I have has the input shaft and output shaft in different planes (not inline). Therefore you cannot couple the two together.

Front wheel drive transaxles have the same problem, the input shaft and output shaft are in different planes and cannot be coupled together.

It is only possible for rear wheel drive transmissions that have the input shaft and output shaft inline with each other. And even then it doesn't garantee that it has that type of locking shaft design. If it has this feature it is termed "direct drive", and if it doesn't it is termed "indirect drive".

So you might think a "direct drive" gearbox would be the best option, but this isn't necessarily so.

You see a direct drive gearbox goes from an input shaft, to a counter (or lay) shaft through a pair of gears, and then back from the counter shaft to the output shaft through another set of gears. So for all ratio's other than 1:1, they have the efficiency loss of going through 2 sets of gears.

An indirect drive gearbox has an input shaft and an output shaft that aren't inline with each other. Therefore the power only ever goes through 1 set of gears, so will be more efficient in every gear other than the direct drives 1:1 gear.

revetec
10-26-2006, 10:25 PM
www.fueleconomy.gov (http://www.fueleconomy.gov/feg/driveHabits.shtml)


Use Overdrive Gears

When you use overdrive gearing, your car's engine speed goes down. This saves gas and reduces engine wear.

Estimates for fuel savings from sensible driving are based on studies and literature reviews performed by Energy and Environmental Analysis, Inc., Washington, DC.

Quote taken from the EPA....

If you have a manual transmission, the lower the shift speed, the better the fuel economy.

Quote taken from Ezine Articles

Use Higher Gears: This might not be of particular importance to those driving automatic transmissions, but getting a car up to cruising speed and putting it in the highest effective gear available uses a lot less fuel.

Quote from MSN

Use a high gear or overdrive when driving at highway speeds. The high gear will reduce engine speed, saving gas and cutting engine wear.

Quote NBC

Get A Manual-Shift Car: Manual-shift cars allow you to change to the highest gear as soon as possible, saving gas.

Everyone else seems to agree on the point that the taller the gear...the more fuel you save (as long as engine RPM isn't too low and the engine is labouring).

Quote from Pneumatic:


If you cruise at a rpm lower or higher than the optimum, then you will use more fuel.

My Quote from before:


I drove my car last night showing the instantaneous fuel usage on my trip computer. I picked the rpm band that the torque of my engine is in it's flatest point. I maintained 100kph in fourth gear and the trip meter said 11.9 litres per 100kph. I then put it in third gear and travelled the same stretch of road and maintained the same road speed and the fuel consumption was reading 12.8 litres per 100kph.

Maintaining the same speed in the same vehicle would make you assume that the same work was being done so the power usage would be similar, with a 2% variation from the extra transimission losses. Wind and rolling resistances are the same. That's a 5% fuel saving in 4th gear.

pneumatic
10-26-2006, 11:15 PM
Everyone else seems to agree on the point that the taller the gear...the more fuel you save (as long as engine RPM isn't too low and the engine is labouring).

I agree with that too, which is why I said "If you cruise at a rpm lower or higher than the optimum, then you will use more fuel" (as you quoted). No-one is debating any of those statements.

The point is;

The most fuel efficient cruising RPM is NOT related to where an engine makes peak torque.

AND

Cars have different top gear ratios depending on the engine and vehicle. Some can be very low like 1,500rpm, others can be quite high like 3,500rpm. Motorcycles even higher...

manolis
10-26-2006, 11:28 PM
Pneumatic,

the RoadLoad program is for those who have not your excel nor your background, especially for the youngsters.

Here is a plot for your discussion (I have ‘stolen’ the basic BSFC plot from internet and added the rest).

http://www.pattakon.com/tempman/BSFC.GIF

Thanks
Manolis Pattakos

revetec
10-26-2006, 11:55 PM
Pneumatic: My point is that if you produce better torque in a lower in the rpm range (which will lower the point in RPM when the engine labours) then you can use taller gearing which then saves fuel. A performance engine which has a higher RPM torque and power band labours at a much lower RPM.

pneumatic
10-27-2006, 12:08 AM
the RoadLoad program is for those who have not your excel nor your background, especially for the youngsters.

Yeah, it is a pity mine needs Excel. I have been learning VBA to make it a stand alone program. :)


Here is a plot for your discussion (I have ‘stolen’ the basic BSFC plot from internet and added the rest).

Ah, that's what we need. You can see that engine is actually at it's most efficient at medium load at about 2,500rpm. Highway cruising is a medium load for most cars (light load for really powerful cars)

You can see with the curves that Manolis drew that light loads it would be most efficient at ~1200rpm (downhill cruising).

But at higher loads like going uphill, it is most efficient operating about 3,500rpm.



My point is that if you produce better torque in a lower in the rpm range (which will lower the point in RPM when the engine labours) then you can use taller gearing which then saves fuel.

That isn't right. Can't you see your own car is the perfect example. It's peak torque is 4800rpm yet it is quite efficient operating low in the rev range. Your car has a performance engine, and it doesn't labour at low rpm. If you retuned it with a very mild cam, so you got peak torque at 3,000rpm, do you think it would make your fuel economy any better?

If an engine has enough power to pull a tall enough gear to allow it to operate at it's most efficient cruising rpm, then it has power to do it. It doesn't matter that it's peak torque is at 1000 or 8000rpm. So long as it has sufficient torque down low to pull the necessary gear ratio to get it to cruise at it's most efficient rpm.

You should be able to tune your Revetec better (generally tuning and better breathing etc), and get it to run higher in the rev range. This will move your peak torque higher and make a big improvement in horsepower. Doing this shouldn't reduce the torque it's producing low in the rev range much at all (it will reduce it a bit, but not much - not enough to cause you to need to select a lower top gear ratio).

revetec
10-27-2006, 12:58 AM
You're moving around the point again....I am not talking about peak torque, I'm talking about low down torque.

Your quote:

So long as it has sufficient torque down low to pull the necessary gear ratio to get it to cruise at it's most efficient rpm.

Your quoting what I'm quoting but then you argue the point against it.

My Caprice has good torque at low RPM and it cruises very nicely at 100kph with the engine doing around 1,300rpm. If a small engine had higher torque down low then instead of being geared to cruise at 100kph doing 2,500rpm, it can be geared taller before it labours, to maybe operate at 2,000rpm. Which saves fuel.
Do you agree because I'm sure that you get better fuel economy in 5th at 100kph than in 4th, or manufacturers would not bother putting an overdrive gear in the transmission?

pneumatic
10-27-2006, 04:24 AM
Your quoting what I'm quoting but then you argue the point against it.

No, we just don't quite understand what each other is saying. I like what I said, that's why I wrote it :p


If a small engine had higher torque down low then instead of being geared to cruise at 100kph doing 2,500rpm, it can be geared taller before it labours, to maybe operate at 2,000rpm. Which saves fuel.

So why do some manufacturers put in an overdrive that makes the engine sit on 2,500rpm, and not 2000rpm?

Part of the answer is that in some cases the car that sits on 2500rpm doesn't have the torque to sit on 2000 in top gear. But a lot of the time you will find they actually do have the power to do that.

The other part of the answer is the engine might not be at it's most efficient at 2000rpm anyway. Manolis's BSFC diagram shows that.

So what I am saying is there are no clear rules of thumb.


Do you agree because I'm sure that you get better fuel economy in 5th at 100kph than in 4th, or manufacturers would not bother putting an overdrive gear in the transmission?

Yes, but not all overdrives are equal either. Manufacturers set-up the gearing so the engine will run at it's most efficient rpm, and be able to pull the tall gear. What I am saying is this rpm varies, and it is almost always below where the engine makes peak torque anyway.

You see you want to be able to accelerate past the cruising speed. If you are cruising at peak torque, then your acceleration will get slower and slower the faster you go. Part of this is because the wind resistance gets greater, but another part is that you are running down the torque curve. The combined effect is rapidly slowing acceleration.

If you cruise below peak torque, then your acceleration may not get slower. The wind resistance will get greater and try to slow your acceleration, but you are running up the torque curve, so you are getting more torque to combat the greater wind resistance. So you may actually end up accelerating faster. And this is what you want. When you go to overtake you at least want the acceleration to stay constant. And it's great if the acceleration gets faster and faster.

On the other hand if you have an engine that the acceleration gets less and less as you try to overtake, it gets a little worrying. You have to plan the overtakes and drop down gears more often, but even when you drop down gears your running on the down slope of the torque curve again (but an even steeper down slope - as you are higher in the rpm).

Does that make any sense? :o



Ok, the thing you said that started all this is that because the Revetec makes good torque down low, it will be better than an engine that makes it's torque higher in the rev range. This is not correct. This is what I object to. I think I have explained the reason why pretty well, but maybe not :confused:

manolis
10-28-2006, 12:03 AM
Brad,

take a look at the plot of Brake Specific Fuel Consumption.
It was posted exactly to expain that the higher gear (and so the lower revs) is not necessarily equivalent to lower consumption.

Take for instance the case of the brown heavy load curve.
Suppose you are driving on a long uphill road with constant speed V Km/h.
So the resistant the engine has to win is constant (let say P1 KW).
To keep the V speed you can:
1. Use 1st gear in gearbox and keep the engine revving at 5000 rpm (pressing as necessary the gas pedal). For each hour you consume P1*0.35 Kg of fuel -as the empty red cycle indicates.
2. Use 2nd gear in gearbox, keep the engine revs (pressing properly the gas pedal) at 3600 rpm. As the resistance to the car motion is the same P1 KW, according the plot your fuel consumption becomes: P1*0.3 Kg / h (the specific consumption at 3600 rpm and 600 units of torque is 300 g/KWh). So you save some 15 to 20% of fuel compared to the case with the 1st gear.
3. Use 3rd gear in the gearbox, keep the gas pedal completely pressed to keep the engine revving at 2400 rpm. Now you have a consumption of around P1*0.35 Kg/h, which is as much as with 1st gear and 15 to 20% more than with the 2nd gear.
With 4th and 5th gear the car cannot continue moving with V Km/h and just decelerates.
So the rule "use the longer gear ratio for economy is not applicable here.

Taking the case with the medium load (the blue dashed curve) you see the same things, i.e the consumption is
with 1st gear : P2*0.52 Kg/Kwh
with 2nd gear : P2*0,33 Kg/Kwh
with 3rd gear: P2*.275 Kg/Kwh
with 4th gear: P2*.320 Kg/Kwh
while 5th gear cannot keep the V speed and the vehicle decelerates.
As you see the best economy - in this case - is achieved with 3rd gear, neither with 2nd nor with 4th (the "rule" says 4th).

In the case of the light load (red curve) the 5th is the gives the best economy with P3*0.280 Kg/Kwh or (P3*280 Kg/Kwh)/V if you prefer the consumption in Kg / Km.

So, according the speed of the vehicle and the resistance of the road, using the BSFC plot of the specific engine you can decide for which gear of gearbox to use.

With the BSFC plot of a specific engine and given the gearbox ratios, you can decide when to shift gear in gearbox to get the best economy. With the RoadLoad program you can decide when is the best moment to shift gears in order to move as fast as possible.

It seems reasonable to create BSFC plots for Revetec engines in order to compare immediately their economy to any other engine's economy, without general rules and long lasting discussions.

Pneumatic,
I was thinking to transfer the RoadLoad from Q-Basic (originally created) to Visual Basic but I never did. If you want the QBasic code to use it as the base for your V-Basic RoadLoad just say so.

Thanks
Manolis Pattakos

kingofthering
10-28-2006, 12:16 AM
so... engineering people, is it possible to install this into a Fiat 500? With it's low weight, it should be pretty fast, but you'd have to create custom mounts.

pneumatic
10-28-2006, 07:43 AM
It seems reasonable to create BSFC plots for Revetec engines in order to compare immediately their economy to any other engine's economy, without general rules and long lasting discussions.

I agree (and said the same thing pages ago). We can argue theory forever, but what we need is some actual test data on this engine.

Manolis, thanks for the offer on the Roadload program. Unfortunately I haven't learnt VB (stand alone version), so wouldn't know what to do with the code yet :rolleyes:

manolis
10-28-2006, 08:58 PM
Kingofthering,

In order to keep the existing mounts of Fiat 500, I erased some zeros from the Sepcific Fuel Consumption Plot.
As it is now, the BSFC plot seems not far from the BSFC plots of the current 1000 cc auto engine, with the torque in Nt*m.
A plot like BSFC is the way (i.e. the tool) to think about consumption and then about maximizing economy.
By the way one more animation regarding PRE was added to the pattakon web site at http://www.pattakon.com/pre/droplet.exe. Comments?

Thanks
Manolis Pattakos

kingofthering
10-28-2006, 09:11 PM
well... It seems that this engine has been discontinued, the website is gone.

revetec
10-30-2006, 03:02 PM
For your information...Maintaining Constant Speed with a accuracy of +/- 5%

http://i84.photobucket.com/albums/k6/revetec/Mathlab_Taurus_3L.jpg

The graph shows an increase in fuel consumption after peak torque is reached.

Rockefella
10-30-2006, 03:09 PM
We should get Revetec, Pneumatic, and Manolis a hotel room.