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

  1. #256
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    Manolis: Your engine ain't that small. Shown below is the Revetec X4 scaled to a 500cc engine with sump and all. I would fit bigger valves and heads but it'll still be smaller. Do a final CAD design with sump and all, then we will compare sizes ok?

    Last edited by revetec; 10-31-2006 at 08:11 PM.

  2. #257
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    Quote Originally Posted by revetec
    The graph came from "The Georgia College of Tech Engineering" Maybe you all should contact the professors there and have a talk with them. It was the 24 valve engine, picked because of its flat torque curve.

    It's fitted with an auto.
    gear ratio 1st gear: 2.77:1
    gear ratio 2nd gear: 1.54:1
    gear ratio 3rd gear: 1.00:1
    gear ratio 4th gear: 0.69:1
    Differential with a gear ratio of 4.266 to 1.

    That was what was in the paper. If you don't agree, take it up with the college professor.
    What was the name of the paper, and do you know if it is [publicly] available online?
    "In theory, theory and practice are the same. In practice, they are not."

  3. #258
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    Quote Originally Posted by revetec
    That was what was in the paper. If you don't agree, take it up with the college professor.
    Brad,

    What exactly was in the paper? The graph is fine, we agree with the graph.

    It was the interpretation of the graph and the rpm at a certain speed for a certain gear that is wrong.

    As I suspected it is an auto gearbox, so the gearing is even taller than I quoted, and therefore the rpm figures you quoted are even further off the mark.

    Do some calc's on those gear ratio's yourself. You said;
    3rd gear - Approx 60kph@4,300rpm and 4th gear Approx 80kph@4,300rpm
    Those figures are wildly inaccurate. Even someone that doesn't understand the math at all would know a V6 family car in top gear (4th in the auto) would not be revving it's guts out at 4300rpm at 80kph.

  4. #259
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    Ooopps....Ha ha ha. just checking if you were all awake. I did it again! I'm kind of addicted to this forum but at the same time I'm flat out designing. I estimated the wheel rolling diameter and stuffed completely up. Ha ha! Oh well....teach me to try and work, while checking on what you guys are posting. Hehehehe!

    The paper was a task sheet to see if the students could work out all the forulaes and come up with the correct figures given as per the graph. It can be accessed from the university. I just found it online but didn't bookmark it sorry.... I'll try and find it again.
    Last edited by revetec; 10-31-2006 at 09:41 PM.

  5. #260
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    Hey I got an idea...Instead of all you arguing with me, how about you guys find actual test figures in different gears and rev ranges and post them here. Because I don't have the time at the moment. How about it?

  6. #261
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    Please note: Heads are just a representation at the moment. Port sizes are the same as similar aircraft engines but would be alot bigger on a motorbike.
    Last edited by revetec; 10-31-2006 at 10:09 PM.

  7. #262
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    Quote Originally Posted by revetec
    Manolis: Your engine ain't that small. Shown below is the Revetec X4 scaled to a 500cc engine with sump and all. I would fit bigger valves and heads but it'll still be smaller. Do a final CAD design with sump and all, then we will compare sizes ok?
    Brad,

    As regards your plot:
    Just think of going from a town at sea-side to a village on the mountain. Think how many times you use 4th gear or 5th gear in your gearbox (maybe none). Think how often you press deeply the gas pedal (too often). The load is heavy not because the speed is high but because you often have to brake and then accelerate quickly on the uphill roads. There is little difference from having the car on a inertia dyno and make repeatedly dyno measurements. This type of loading / driving is more realistic than cruising on a level road with constant speed (the last is the case in a boat or an airplane).

    As regards the external dimensions of Junkers PRE.
    The Junkers-PRE engine has two stroke power concentration (with actually four stroke operation, think about it or take a look at http://www.pattakon.com/pre/index.html to see why). So your X4 engine has to be of 800cc (according Pneumatic) or over 1000cc (according me) to be comparable in terms of torque and power output.
    From the Junkers-PRE the only that is missing is the oil pan. OK.
    From your X4 there are missing four cylinder heads.
    If you remove the two cylinder heads from a BMW boxer, you get an acceptable bike, but as they are now the BMW's boxers are almost as wide as cars.
    Think also about the weight of the Junkers-PRE and its cost. I know that the cylinder head is the most expensive part of Honda Civic DOHC VTEC (B16A2 1600cc and 1800cc) to buy, and its weight is some 23 Kg. A look at http://www.pattakon.com/vvar/OnBoard/Assembly.exe may help. We estimate the Junkers-PRE 500cc weight be around that number.

    Thanks
    Manolis Pattakos
    Last edited by Egg Nog; 12-06-2006 at 03:34 AM.

  8. #263
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    Quote Originally Posted by manolis
    Brad,

    From the Junkers-PRE the only that is missing is the oil pan. OK.
    From your X4 there are missing four cylinder heads.
    The cylinder heads are on the engine! hahahahhah! They are exactly the same dimensions and layout of a competitor's cylinder heads except I have liquid cooled them. Because they are aircraft heads, they are only two valve heads.

    BTW: It'll take more than an oil pan to get your line drawing to work. The X4 model has oil pump, water pump, alternator and everything else to make it run. Far out! Our cylinder heads are 2.2kg each making a total of 8.8kg.

    BTW: Increasing it another 300cc changes the dimensions by about 15mm.
    Last edited by revetec; 10-31-2006 at 10:56 PM.

  9. #264
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    Quote Originally Posted by revetec
    Please note: Heads are just a representation at the moment. Port sizes are the same as similar aircraft engines but would be alot bigger on a motorbike.
    Brad,

    Using push rods and side camshafts (how many camshaft? where located? how many valves per cylinder?) is not a step ahead, I think. If you can achieve good aspiration, high revs limit etc with such short cylinder heads, you could save BMW's boxer and Moto-Guzzi's V-90 from being as wide and as tall as they are now.

    Thanks
    Manolis Pattakos
    Last edited by Egg Nog; 12-06-2006 at 03:34 AM.

  10. #265
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    Dear Manolis:

    This is an aircraft engine. They only do 3,500rpm tops because if they did more the prop would cavitate. Between each side's cylinders there is a camshaft (2). Aircraft suffer from a wide range of thermal expansion so hydraulic lifters are preferable and fitted. Only 3,500rpm hydraulic lifters are good and low maintanance.

    Again. Just stuck it in your bike picture for scale. I'm not looking at fitting it into a bike for a while.

    Cheers
    Last edited by revetec; 10-31-2006 at 10:59 PM.

  11. #266
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    Brad,

    Just in case X4 is going to fit into this bike:



    Thanks
    Manolis Pattakos

  12. #267
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    Cool! But the heads are a bit bigger than the scale of the engine but that's ok. The Yamaha head is a five valve I think? I've seen one and it's a piece of work! But anyway, we are not looking at bikes at the moment.

    Cheers
    Last edited by revetec; 11-01-2006 at 01:41 AM.

  13. #268
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    Quote Originally Posted by santostripoli
    X4 is still far more superior due to its weight advantage (power to weight ratio)
    So is gasturbines + they have less moving parts and therfor more reabile. What did you solve?

    Quote Originally Posted by revetec
    lol...we are thinking alike on some topics.
    Back to the torque discussion:
    If Engine A produces 200 pounds-feet of torque at 2,000 RPM, and Engine B produces 200 pounds-feet of torque at 5,000 RPM, Engine A will have more towing or hauling capability at lower speeds, because it reaches its maximum torque at the lower RPM. Engine B will have more towing or hauling capability at higher speeds, because it reaches its maximum torque at the higher RPM.
    But the higher the RPM, the more fuel is consumed. Generally torque is important from an acceleration off the mark point of view. The heavier the vehicle or load, the more benificial higher torque at low RPMs.

    For towing capasety we have gears. And rpm is not interesting, but cylinderstrokes per second. The big friction losses is in cylinderwall vs piston and air resistance in the valves.


    Quote Originally Posted by revetec
    This theory all looks and sounds good but......

    I drove my car last night showing the instantaneous fuel usage on my trip computer. I picked the rpm band that the torque of my engine is in it's flatest point. I maintained 100kph in fourth gear and the trip meter said 11.9 litres per 100kph. I then put it in third gear and travelled the same stretch of road and maintained the same road speed and the fuel consumption was reading 12.8 litres per 100kph.
    and the reason is that you use higher piston cycles and not rpm.

    Try the revetec and run it on 100kph in 3 and 4't gear while making shure your gearing betwen pistons and the weels are the same in both experiemts.

    I mean that both engines should make the same piston strokes per cylinder per rpm on the weel.

    And theory is allways right. If the result is not corect it's because it's used wrong.

  14. #269
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    In response to your quote:

    [QUOTE=stian1979]So is gasturbines + they have less moving parts and therfor more reabile. What did you solve?

    My response:
    Are gasturbines as flexible as the CCE concept? No
    Are gasturbines capable of being integrated within conventional engines? No
    Is gas a viable alternative to petrol/diesel? No
    The Revetec engine appears to have
    (1) effeciency (power & torque)
    (2) the flexibility to be integrated within existing engine platforms
    (3) packaging effeciencies
    (4) weight saving
    (5) fuel economy

    = a very exciting development in the development of the international combustion engine.

    Automotive companies get excited when there is a weight gain of 10kg; this engine will save more weight + improve effeciency + fuel economy.
    Last edited by santostripoli; 12-04-2006 at 06:46 PM.

  15. #270
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    Quote Originally Posted by stian1979
    For towing capasety we have gears. And rpm is not interesting, but cylinderstrokes per second. The big friction losses is in cylinderwall vs piston and air resistance in the valves.

    and the reason is that you use higher piston cycles and not rpm.

    Try the revetec and run it on 100kph in 3 and 4't gear while making shure your gearing betwen pistons and the weels are the same in both experiemts.

    I mean that both engines should make the same piston strokes per cylinder per rpm on the weel.

    And theory is allways right. If the result is not corect it's because it's used wrong.
    Dear stian1979, I think you should go back and read all previous postings before you just quote one part of a discussion.

    The discussion is about changing the gearing ratios to suit different charateristics from different engines and the effect on fuel economy it makes. Not keeping the ratios the same

    BTW: We don't use higher piston cycles than a conventional engine, we use the same. (ie. Two piston strokes per piston per RPM) This has been discussed previously in this thread.

    Cheers
    Last edited by revetec; 12-05-2006 at 08:25 PM.

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