A work of pure genius! - Brilliant "Revetec" Engine

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

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.

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

I came across this thread today.

Please take a look at [URL="http://www.pattakon.com/greco/index.html"]http://www.pattakon.com/greco/index.html[/URL] or start from [URL="http://www.pattakon.com"]http://www.pattakon.com[/URL]
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 [URL="http://www.pattakon.com/pre/index.html"]http://www.pattakon.com/pre/index.html[/URL] (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 [URL="http://www.pattakon.com/pre/PRE13.exe"]http://www.pattakon.com/pre/PRE13.exe[/URL] or
[URL="http://www.pattakon.com/pre/PRE14.exe"]http://www.pattakon.com/pre/PRE14.exe[/URL] or [URL="http://www.pattakon.com/pre/blueprint.pdf"]http://www.pattakon.com/pre/blueprint.pdf[/URL] .

Thank you
Manolis Pattakos

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
[B][COLOR="Red"][I]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! :-)[/I][/COLOR][/B]

Dear Brand,

Thank you for your reply.

[INDENT]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.[/INDENT]

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).



[INDENT]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.[/INDENT]

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 [URL="http://www.pattakon.com/vva/VVA_Idle/VVA_Idle.htm"]http://www.pattakon.com/vva/VVA_Idle/VVA_Idle.htm[/URL] and the video [URL="http://www.pattakon.com/vvar/OnBoard/A1.MOV"]http://www.pattakon.com/vvar/OnBoard/A1.MOV[/URL] etc, etc in [url]www.pattakon.com[/url] 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.



[INDENT]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.[/INDENT]

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 ( [URL="http://www.uspto.gov/patft/index.html"]http://www.uspto.gov/patft/index.html[/URL] ). 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

what the.........

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.

[B]I have been talking about breathing not about the combustion cycle.[/B]

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.

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

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.
[IMG]http://i84.photobucket.com/albums/k6/revetec/conrodratio.jpg[/IMG]

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 [url]http://www.revetec.com[/url]

[I]PS. Never doubted the benifits of variable valve timing and theirs is probably good.[/I]

[QUOTE=revetec]...
[IMG]http://i84.photobucket.com/albums/k6/revetec/conrodratio.jpg[/IMG][/QUOTE]

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

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;
[quote]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.[/quote]

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.

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

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

[quote]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. [/quote]

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;
[quote]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.[/quote]

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.

[quote]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), [/quote]

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.

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?

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.

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.

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.

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

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

[QUOTE=santostripoli]Pneumatic
I think you are being a little unfair with Brad[/QUOTE]

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.

[quote=revetec]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. [/quote]

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.

[quote=revetec]same fuel consumption at 4,000rpm as at 2,000rpm and doubled the power[/quote]

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).

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.

[quote]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[/quote]

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.

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.

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.

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.

[QUOTE=revetec]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. [/QUOTE]

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 ;)

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.

[B]Gents[/B]

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:

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%.

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.

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;
[URL="http://www.offroadvw.net/exceldyno/"]http://www.offroadvw.net/exceldyno/[/URL]

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.

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!

[QUOTE=revetec]Everything you need to design a Revetec or standard engine.[/QUOTE]

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.

[B]A few corrections[/B]

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.

[IMG]http://www.pattakon.com/tempman/piston_acc.GIF[/IMG]

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.


[B]PRE engine[/B]

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.

[URL="http://www.pattakon.com/pre/PRE13.exe"]http://www.pattakon.com/pre/PRE13.exe[/URL]
[URL="http://www.pattakon.com/pre/PRE14.exe"]http://www.pattakon.com/pre/PRE14.exe[/URL]
[URL="http://www.pattakon.com/pre/blueprint.pdf"]http://www.pattakon.com/pre/blueprint.pdf[/URL]

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.


[B]Harmonic engine[/B]

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

[IMG]http://www.pattakon.com/ppe/ppe_files/image003.jpg[/IMG]

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 [url]www.pattakon.com/educ/harmonic.exe[/url] (details at selection 15). It seems it manages breathing too well for an 'infinite' rod - or pure sinusoidal - piston motion.


[B]Pattakon's GRECO engine[/B]

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):
[IMG]http://www.pattakon.com/tempman/TRI_SINGLE_lobe.GIF[/IMG]

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.
[IMG]http://www.pattakon.com/tempman/greco_single.JPG[/IMG]

The application of the previous in a four in line GRECO engine having a unique shaft
[IMG]http://www.pattakon.com/tempman/I4.JPG[/IMG]

Pattakon's 8 cylinder in H arrengement GRECO engine having two counter-rotating camshafts
[IMG]http://www.pattakon.com/tempman/greco8.JPG[/IMG]

At [URL="http://www.pattakon.com/greco/index.html"]http://www.pattakon.com/greco/index.html[/URL] 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

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:

[IMG]http://www.pattakon.com/tempman/pre_junkers.JPG[/IMG]

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:

[IMG]http://www.pattakon.com/tempman/fly.JPG[/IMG]

Thanks
Manolis Pattakos

[QUOTE=manolis]But think of a Junkers-PRE engine (with Otto or Diesel cycle). Like this one:[/QUOTE]

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.

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.

[IMG]http://i84.photobucket.com/albums/k6/revetec/grecomulti.jpg[/IMG]

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

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?

[QUOTE=pneumatic]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.[/QUOTE]

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:
[IMG]http://www.pattakon.com/tempman/pre_junkers_supercharged.JPG[/IMG]
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

[IMG]http://www.pattakon.com/tempman/pre_junkers_clutch.JPG[/IMG]

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

[QUOTE=revetec]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[/QUOTE]

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:
[IMG]http://www.pattakon.com/tempman/greco_short_stroke.JPG[/IMG]

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

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.

[B]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.[/B]

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.

[IMG]http://i84.photobucket.com/albums/k6/revetec/greco_s_stroke.jpg[/IMG]

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?

[B] Please Note: I'm not criticizing the design concept. Just looking at compactness of a production model for my reference. [/B]

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.

[B]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?[/B]

Cheers

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.

[IMG]http://i84.photobucket.com/albums/k6/revetec/common_knocker.jpg[/IMG]
(Common Knocker)

This can be in the Pattakon configuration and use gears to transfer power and time the engine, such as suggested by Manolis.

[IMG]http://www.pattakon.com/tempman/pre_junkers_clutch.JPG[/IMG]

[IMG]http://www.pattakon.com/tempman/pre_junkers_supercharged.JPG[/IMG]

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

[IMG]http://i84.photobucket.com/albums/k6/revetec/pullrodgraph2.jpg[/IMG]

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?

[QUOTE=revetec]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. [/QUOTE]

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.

[QUOTE=manolis]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.[/QUOTE]

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:
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... :-)