Novice
It was written:
“And that should give Manolis heaps of time to get the proper software and provide everyone with decent modern day data for his engine rather than relying on Pythagoras, Archimedes and Aristotle for his flawless mathematical theories.”
. . . and Plato, and Tales, and Pittakos and over a thousand others like them, born 2,500 years ago, still alive and leading.
Thanks
Manolis Pattakos
Novice
Evetec wrote:
“BTW...we balanced out only 50% of the reciprocating mass as we were instructed to do by a leading performance engine balancer, and the engine runs silky smooth (Same as a conventional engine balancing). I will post a video soon on our website.”
The 50% reciprocating mass was proposed because the two “double” pistons reciprocate in phase, with their cylinders inclined for 60 deg from the vertical axis. The two double pistons, as regards the inertia forces they produce, are equivalent to a unique mass (of weight equal to the sum of the weights of the two double pistons) reciprocating along the vertical axis at a stroke half of the stroke of each piston alone (in other words, the center of gravity of the two pistons is always in the vertical axis and performs a reciprocation of half stroke of the actual stroke of the X4 engine).
And here is something good for Revetec engines.
In a conventional engine, the piston dwells at the BDC for longer than at TDC (the smaller the con-rod to stroke ratio, the longer the dwell at BDC and the shorter the dwell at TDC).
In Revetec’s engines, the piston dwells at TDC exactly as at BDC.
This results from the fact that the two pistons move as a single body: the motion one piston makes at TDC, is the exact motion its mate piston makes at BDC.
The necessary symmetry of the piston motion profile of the Revetec engine is significant for its balancing: the Revetec engines are free from 2nd order inertia forces (as well as any other “even order” inertia force). Simple trigonometry says so.
I.e. there is no inertia force of second or fourth or sixth or . . . order.
Thanks
Manolis Pattakos
Member
Manolis: You are still wrong about the bore and stroke, so no need for your maths.
Please note: Compression ratio stated is a rounded figure to 9:1. You don't know my Non-zero deck volume, head volume, piston design/volume or anything else. So you are wasting your time guessing. All I can say is that you are off a fair bit.
BTW: By the end of the week the compression ratio will be changed again for further tests, without changing the head gaskets.We can actually play around with the non-zero deck volume or piston TDC height. Part of our design we are not showing off currently and is why our engine is actually called the Controlled Combustion Engine (CCE). Have you ever wondered why we called it the CCE? Soon.... just be patient...
You'll be interested in our combustion technology when we release the details later this year.
I didn't say that the gasket was a different size, just stated that you don't know.I think you would better use your time working on your designs.
The two piston assemblies balance out 66% of each others reciprocating mass. We are balancing out 50% of the remainder. This is normal in engine balancing due to the recoil experienced by the cylinders and heads. We were consulted on this by a leading performance engine balancer, and is a good starting point. We have designed the balance weights in a way we can alter them in the fine tune/balance step (mid year). Our balancing is also quite different from a conventional engine.
You are right about the second order balancing.
Novice
Hi! the forum. I've been looking over this thread of Egg Nog's about the brilliance of the revetec engine. Things seem to get a little heated from time to time. I don't think any great advances in internal combustion engines will come out changes in geometry unless a specific change allows the imposition of a different combustion paradigm such as oxidising fuel below the flammability limits. A SI engine is an SI no matter what the shape.
Cheers Gaz.
Member
We have run our engines with maximum performance with an air/fuel ratio at 4,000rpm full load between 14.7:1 to almost 30:1. No other reciprocating ICE to my knowledge can run this lean with the performance we are achieving.Originally Posted by Gaz.Guzzle
Enthusiast
Doesn't that mean that the "Maximum performance" (whatever that means) that you get out of it when running on 14.7:1 AF ratio, sucks?
Power, whether measured as HP, PS, or KW is what accelerates cars and gets it up to top speed. Power also determines how far you take a wall when you hit it
Engine torque is an illusion.
Member
No. It means that the higher the revs we go, we're increasing power but fuel consumption remains the same. It's part of our technology and at the moment it is not achievable at lower revs. We reported on this on our Mahindra report posted on our website.
2.4 litre X4 Aircraft Engine 1st Start and Running
Last edited by revetec; 03-27-2007 at 08:25 PM.
Enthusiast
I see so any advantage in efficiency is only achievable at higher revs in your engine to date...
Also it means that from idle up to where you are making good power per unit fuel consumed you are operating at lower efficiency than a typical car engine.
Power, whether measured as HP, PS, or KW is what accelerates cars and gets it up to top speed. Power also determines how far you take a wall when you hit it
Engine torque is an illusion.
Member
No. We have an overall mechanical advantage of torque all the way through the range (as the dyno graph showed that was previously posted) but we also have a very new combustion technique that allows us to start off with the same air/fuel ratio as a conventional engine and then lean the mixture off as the revs increase.
Enthusiast
Ok so if you are making more power as rpm rises then you must only lean out the mixture slowly... at least slower than you increase revs.
EDIT: I can't find the dyno chart....
Power, whether measured as HP, PS, or KW is what accelerates cars and gets it up to top speed. Power also determines how far you take a wall when you hit it
Engine torque is an illusion.
Member
We were running 14.7:1 air/fuel ratio at 2,000rpm and about 30:1 air/fuel ratio at 4,000rpm which keeps the fuel consumption constant throughout that range, although the Hp almost doubled. As part of our system, the Lambda sensor always reads that we are running 14.7:1 ratio which is great for our feedback control. This was proved at an independent automotive company's test cell, and reported on our website regarding Mahindra visit.
Enthusiast
How is that possible?We were running 14.7:1 air/fuel ratio at 2,000rpm and about 30:1 air/fuel ratio at 4,000rpm which keeps the fuel consumption constant throughout that range, although the Hp almost doubled. As part of our system, the Lambda sensor always reads that we are running 14.7:1 ratio which is great for our feedback control. This was proved at an independent automotive company's test cell, and reported on our website regarding Mahindra visit.
How can a lambda sensor show 14.7:1 a/f ratio when you are running almost 30:1? How do you know you are running 30:1?
If power "almost" doubled that means you are making slightly less torque at 4000rpm, correct?
Have you released ratings for lbs. of fuel used per HP per hour when you are running at 14.7:1 a/f ratio (at 2000rpm)? If not I hope that you will soon.
I am honestly interested in this perculier phenomena
Power, whether measured as HP, PS, or KW is what accelerates cars and gets it up to top speed. Power also determines how far you take a wall when you hit it
Engine torque is an illusion.
Member
I can't really go into how we do it too much but a Lambda sensor reads OX2 not fuel. Usually a rich mixture shows no OX2 and a lean mixture shows some OX2. We are running a very lean mixture with our burn control and the small amount of OX2 gives a false Lambda reading. We know how much fuel we are putting in from injection tables in previous engine ECUs and independent fuel tests.
After we release all our figures (Over the coming months we will release several lots of information regarding our latest tests) I will explain how we achieve this.
Cheers
Rookie
How about the American designed and made MYT engine.......all I can say is wow. Revetec smevetec, not even close to the MYT.
http://www.youtube.com/watch?v=kGlUZg2pC0Q
Member
I've seen this before:
Lets look at the manufacturing of this MYT engine. To get the pistons in the donut chamber has to be split, this is not good for sealing with rings running around in there and the tolerance would have to be below 1 thou. Secondly the heat dissipation from the pistons would be a problem. The machining of the pistons and chamber would be difficult. How would you hone such a shape to bed the rings in? Cooling this engine will be a difficult task. At the moment it as cooling fins on the outside, but how about the sides and inside of the donut? The fins would have to be huge to use it as an engine (Remember that the more air and fuel burnt the larger the amount of heat has to be dissipated.)
Why do you think the demonstration is using air to drive it? He says the idle and friction is so low, this is when it has no pumping pressures. This engine would not run this low rpm firing normally. You can get any engine running below that speed as an air motor. I could build a very large air vane pump that has no stop/starting components that would not only be more efficient but would have a larger operating RPM.
Even though he says it is running only running half of the engine, it jumps around with a huge out of balance.
I will also comment that holding the piston from one side, I would doubt that it would be reliable enough to operate, especially at 25:1 quoted on their website.
Anyway...US$4 million in 5 years and no engine running on their website. Is this an air motor or an engine?
Anyway I'll keep an eye on it to see if they actually get some combustion happening inside it. My thoughts is that it maybe a long time coming if it comes at all, but then again I don't know too much about this company or where they are at presently.
Where are all the ancillaries on the MYT engine like manifolds etc? Not a good comparison of size.
What is the Rev range?
Last edited by revetec; 04-01-2007 at 06:15 PM.
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