-
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?
-
[QUOTE=Matra et Alpine]Not sufficient to prevetn some bypass and limiting it's anti-pollution capability.[/QUOTE]
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.)
[QUOTE=Matra et Alpine]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 ?[/QUOTE]
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.
[QUOTE=Matra et Alpine]j'ai les voitures francaises. J'ai du apprendre comment lire et parler le francais[/QUOTE] so you like renaults and Puegeots? and congradulations with being able to read and speak and write french!
Right on to the main attraction:
[QUOTE=stian1979]The rigid reciprocating piston assembly is not balanced.[/QUOTE] Yes it is balanced but the way it moves will create vibration.
[QUOTE=stian1979]Sure, the cams are balanced (they would be even if they weren't counter-rotating), but so is a crankshaft.[/QUOTE] 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!
[QUOTE=stian1979]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.[/QUOTE] 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!
[QUOTE=stian1979]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.[/QUOTE] 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.
[QUOTE=stian1979]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.[/QUOTE] 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.
[QUOTE=stian1979]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:[/QUOTE] 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.
[QUOTE=stian1979].. but provide no information regarding how their device, which [B]never pushes at a tangent to the travel of the cams[/B], 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.[/QUOTE]
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.
[QUOTE=stian1979]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:[/QUOTE] 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!
[QUOTE=stian1979]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.[/QUOTE] 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!
-
[quote=hightower99]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.)[/quote]
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 :(
[quote]There is a movie on the website that is an episode from a french discovery channe[/quote]
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.
[quote]so you like renaults and Puegeots? and congradulations with being able to read and speak and write french![/quote]
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 !!!!!
[quote]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![/quote]
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
-
[QUOTE=stian1979]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?[/QUOTE]
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
-
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.
[QUOTE=hightower99]
BTW has nobody figured out that HP is TorqueXRPM where as Torque is a stationary measure of force? HP is what moves the car![/QUOTE]
Exsactly
[QUOTE=hightower99]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![/QUOTE]
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.
[QUOTE=KnifeEdge_2K1]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[/QUOTE]
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.
[QUOTE=hightower99]
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!
[/QUOTE]
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.
[url]www.cmcpower.com[/url]
-
[quote=stian1979]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[/quote]
THIS was covered before.
A boxer has OPPOSING pistons and so s self-balanced.
You are confusing a V180 configuration.
[quote]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.[/quote]
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
[quote]To be honest I like the Sytec engine design bether.
[URL="http://www.cmcpower.com"]www.cmcpower.com[/URL][/quote]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.
-
[QUOTE=stian1979]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.
[/QUOTE]
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
-
[QUOTE=Matra et Alpine]THIS was covered before.
A boxer has OPPOSING pistons and so s self-balanced.
You are confusing a V180 configuration.[/QUOTE]
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.
[QUOTE=KnifeEdge_2K1]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[/QUOTE]
Yes so what is the magic of 2,9 times the torque when you nead 3 times the work cycles to perform it?
[QUOTE=KnifeEdge_2K1]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[/QUOTE]
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?
-
[QUOTE=stian1979]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?[/QUOTE]
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 ... :(
-
There is alot of things out there.
New ways of transfering work from combustion to rotation.
[url]www.revetec.com[/url]
[url]www.quasiturbine.com[/url]
[url]www.cmcpower.com[/url] (I kind of like this one myself even it has the balance problem)
[url]www.splitcycle.com.au[/url]
Some guys trying to make V configuration with Scotch Yoke cycle [url]www.sliderengine.com[/url]
New top and valve designs.
[url]www.jack-brabham-engines.com[/url]
[url]www.coatesengine.com/index.html[/url]
[url]www.rcvengines.com[/url]
[url]www.new4stroke.com[/url]
Thanks Matra et Alpine I have totaly forgoten about the rand cam.
I was looking at it some years ago.
[url]www.regtech.com[/url]
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?
[url]www.plug2work.com/angellabsllc/index.html[/url]
This one is simpe
[url]www.archerengine.dabsol.co.uk/detail.htm[/url]
What is up with the australians and crankshafts?
The all mighty australian crank less engine (aksial crank I would call it)
[IMG]http://i43.photobucket.com/albums/e353/stian1979/bxtai0489t.jpg[/IMG]
[IMG]http://i43.photobucket.com/albums/e353/stian1979/crankless-figure.jpg[/IMG]
[IMG]http://i43.photobucket.com/albums/e353/stian1979/crankless80cm.jpg[/IMG]
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.
-
[quote=stian1979]What is up with the australians and crankshafts?
The all mighty australian crank less engine (aksial crank I would call it)[/quote]
It's words that rhyme with wank that cause them problems.
It goes back to childhood and being caught at it :D
[quote]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.[/quote]
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
-
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.
-
[quote=stian1979]Stirling engine has a limited use since it can't take quick changes in load. [/quote]
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 !!!!
[quote]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.[/quote]
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.
[quote]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.[/quote]
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.
[quote]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.[/quote]
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 !!!
-
[QUOTE=Matra et Alpine]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 !!![/QUOTE]
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
[IMG]http://i43.photobucket.com/albums/e353/stian1979/torqueandbearing.jpg[/IMG]
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
[IMG]http://i43.photobucket.com/albums/e353/stian1979/Napier_deltic_animation.gif[/IMG]
And with compund where you can inject fuel into the exhast to get some extra hp out of the turbine when neaded
[IMG]http://i43.photobucket.com/albums/e353/stian1979/Napier_Nomad.jpg[/IMG]
The smal english companys really know how to make engines, to bad they are gone or close to.
-
[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, 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 :(
[quote]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. [/quote]
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
[IMG]http://8w.forix.com/altpower/williamscvt.jpg[/IMG]
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 ???
[quote]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.[/quote]
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 :)
[quote]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[/quote]
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 ??
[quote]The smal english companys really know how to make engines, to bad they are gone or close to.[/quote]
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.
