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Thread: Influence of engine configuration over its performance

  1. #16
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    we all had a good chat about engine types at

    http://www.ultimatecarpage.com/forum...ad.php?t=10545

  2. #17
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    [B]OPPOSED PISTON IN HEAD

    (1) The 6-stroke engine is fundamentally superior to the 4- stroke because the head is a net contributor to, and an integral part of the power generation within the engine, unlike a cam only absorbing power.
    (2) The 6stroke is thermodynamically more efficient because the change in volume of the power stroke is greater than the intake, compression, & exhaust strokes.
    (3) The compression ratio can be increased because of the absence of hot spots in the combustion chamber.
    (4) The rate of change in volume during the critical combustion period is less than in a 4stroke.
    (5) The absence of valves within the combustion chamber allows design freedom.
    (6) A one-piece engine from crankshaft to upper shaft becomes feasible. No head gasket.
    (7) Fewer components, 15 per cylinder compared to 40 for a 4-stroke. Therefore the cost of manufacture is much less.
    (8)Can be fitted to standard engine blocks so the market is much larger than the OEM sector, also includes the retrofit aftermarket sector.
    The engine has proven to be robust on the racetrack, & have significant advantages over 4-strokes
    (1) The valving is desmodromic
    (2) There are no valves to drop or bounce.
    (3) The rev limit is only what the bottom end can stand.
    (4) Gas flow on intake increase of 20%.
    (5) No possibility of engine damage if the timing belt slips or snaps
    (6) the reed valves are so close to the intake ports that their tips become the virtual port opening. This achieves variable port area & variable engine demand valve timing. The tips open late & small amounts with low throttle settings & open early & fully at full throttle
    www.sixstroke.com
    Last edited by malbeare; 02-10-2007 at 01:36 PM.

  3. #18
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    Quote Originally Posted by pimento
    You're making sense, but there's a lot of information to divulge here. Have you tried www.howstuffworks.com yet? A good basics there. Also, you could trawl the technical forums here for similar threads, there have been several on this kind of topc.
    lol a classic response, "visist the website howstuffworks.com" lol
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  4. #19
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    Let's say you are designing a car from the ground up.
    You have to decide what you want out of the car performance wise.
    You then have to decide what you want as a package. Passengers, interior space, footprint etc . . .
    Then you will have to decide the target market, and cost of the vehicle. Taking into consideration the competition.
    You will then have to go back and forth to get the best possible compromise.
    You'll either have to take into account what engines your company currently has or if you are building a new engine it will have to fit into a platform stratergy to make it feasable.

    But then you may be asking say for a three liter engine what's the best option.
    V6, inline 6, Inline 4, V4, V5.
    But now you are working with off the shelf engines and again you are dealing with a million different variables and you have to take into account what market that engine was aimed at when it was designed. Unless you are building a bespoke engine, but you are still look at life cycle, cost . . . it goes on.

    The only engines that seem to comply with your question would be racing engines that are limited by there capacity only. Do they exist?
    The most relevant example has been brought up already.
    The Moto GP class. But still there is the massive variance in team budget. And because they are bikes it is hard to tell as so much is dependent on the rider, chassis and general setup. Then there's the riders condition, comfort level and feel on any given day.
    Ontop of which you have no idea what gear ratios they are using how their tyres are performing etc. So you have to take them out of the vehicle and do a side by side comparison on the dyno. But now ram air isn't factoring in la la la la . . .
    I think the question is almost unanswerable.

    Let's not forget 2 or 4 stroke.
    Last edited by 90ft; 02-16-2005 at 06:51 AM.

  5. #20
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    Quote Originally Posted by pimento
    In a zig-zag arrangment, I think. It's probably the VR6 block with one cylinder lopped off. The point is a larger engine than the 2 litre I4, yet it can share parts with it.
    but wouldnt a V5 be off balance?
    pondering things

  6. #21
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    Quote Originally Posted by targa
    but wouldnt a V5 be off balance?
    depends on the crank and the firign order.
    In one configuration it's possible to have an OVERLAP of the combustion cycles which actually helps smooth some of it out.
    I dont' know what the VW does.
    The Honda V5 bike is raced with differeing crank angles and firing orders to suit different tracks performance needs
    "A woman without curves is like a road without bends, you might get to your destination quicker but the ride is boring as hell'

  7. #22
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    Quote Originally Posted by Matra et Alpine
    depends on the crank and the firign order.
    In one configuration it's possible to have an OVERLAP of the combustion cycles which actually helps smooth some of it out.
    I dont' know what the VW does.
    The Honda V5 bike is raced with differeing crank angles and firing orders to suit different tracks performance needs

    Doesn't Honda also has different sized pistons in the two banks.
    The bank with two pistons are larger than those in hte bank of three.

  8. #23
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    Quote Originally Posted by malbeare
    [B]OPPOSED PISTON IN HEAD

    (1) The 6-stroke engine is fundamentally superior to the 4- stroke because the head is a net contributor to, and an integral part of the power generation within the engine, unlike a cam only absorbing power.
    (2) The 6stroke is thermodynamically more efficient because the change in volume of the power stroke is greater than the intake, compression, & exhaust strokes.
    (3) The compression ratio can be increased because of the absence of hot spots in the combustion chamber.
    (4) The rate of change in volume during the critical combustion period is less than in a 4stroke.
    (5) The absence of valves within the combustion chamber allows design freedom.
    (6) A one-piece engine from crankshaft to upper shaft becomes feasible. No head gasket.
    (7) Fewer components, 15 per cylinder compared to 40 for a 4-stroke. Therefore the cost of manufacture is much less.
    (8)Can be fitted to standard engine blocks so the market is much larger than the OEM sector, also includes the retrofit aftermarket sector.
    The engine has proven to be robust on the racetrack, & have significant advantages over 4-strokes
    (1) The valving is desmodromic
    (2) There are no valves to drop or bounce.
    (3) The rev limit is only what the bottom end can stand.
    (4) Gas flow on intake increase of 20%.
    (5) No possibility of engine damage if the timing belt slips or snaps
    (6) the reed valves are so close to the intake ports that their tips become the virtual port opening. This achieves variable port area & variable engine demand valve timing. The tips open late & small amounts with low throttle settings & open early & fully at full throttle
    (7) air assisted fuel injection has unsurpassed (5 micron with 20% air premix) fuel mixture preparation directly into the cylinder without the inhibiting poppett valve in the way, just a lovely big port. And the injector is protected from combustion.
    Malbeare
    http://www.jack-brabham-engines.com/
    This indeed looks very interesting, and welcome to UCP. I hope moderators will not delete this as spam (unwanted commercial activities) because this goes beyond the ordinary. Not being an engineer I will have to study very carefully how the concept works, but the idea of being able to adapt exisiting engines is very interesting. Nevertheless, I was not too impressed with the computer expected output for the Ducati twin (86 BHP) compared to what the conventional version produces. What stage of development are you in? Where do you see further room for improvement?
    "I find the whole business of religion profoundly interesting, but it does mystify me that otherwise intelligent people take it seriously." Douglas Adams

  9. #24
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    Quote Originally Posted by 90ft
    Doesn't Honda also has different sized pistons in the two banks.
    The bank with two pistons are larger than those in hte bank of three.
    Not accordgin to the tech articles in the racing papers.
    BUT you never know with Honda WHAT they might have developed.
    Logically it doesn't make much sense as it introduces an imbalance that has to be countered.
    Do you have any references or links on it ??
    "A woman without curves is like a road without bends, you might get to your destination quicker but the ride is boring as hell'

  10. #25
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    Quote Originally Posted by Matra et Alpine
    Not accordgin to the tech articles in the racing papers.
    BUT you never know with Honda WHAT they might have developed.
    Logically it doesn't make much sense as it introduces an imbalance that has to be countered.
    Do you have any references or links on it ??

    I can't get into Moto GP.com but if there is anything it would be on that site in the archives.
    I was sure the first V5 was as I described.
    I'm not sure now though.

  11. #26
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    henk4,
    Thankyou for your comments.
    Alan Cathcart quote after testing the Ducati Beare sixstroke
    "One thing he certainly doesn't need to worry about is torque, which together with the crisp responsive throttle pick-up and the reduced vibration - even compared to a smooth-action 90 degree V-twin - are three strong points of the six-stroke motor. The Beare engine is unbelievably muscular in terms of torque, and from very low revs, to
    This is in part due to the upper piston cancelling out some of the motion imparted to the block by the main piston , the disks also play a part in keeping vibration low.
    1 the piston speed of the upper piston is lower than the main piston so the wear rate is lower.
    2 Mechanically the engine is silent as there is no tappet noise. The scotch yoke is a silent sliding action with no sudden changes in direction. The shape of the exhaust lip can be designed to give any desired effect to the exhaust note, from a sharp crack with a flat lip to a soft thump with a rounded lip.
    3. The disk has no problems as carbon buildup is wiped off to the desired clearance. There is a protruding boss that the disk has minimal clearance to affect a low-pressure labyrinth seal. During the initial run in period the disk may rub this soft bronze to a clearance of 1 to 2 thousandth of an inch.
    The Beare head offers an array of advantages, but it specifically offers a compact combustion chamber with a 50 per cent squish. Thus, the combustion in the center of the piston is concentrated, increasing the flame speed and the speed of combustion. In doing so the thermal stress on the piston is actually reduced.
    2. An added benefit of this configuration is that it allows a higher bore stroke ratio, due to a lesser expansion of the piston. As there are no cut outs for valves, the crown of the piston can be slightly domed for higher strength and less weight. The 50 per cent squish factor keeps the edges of the piston from being exposed to the flame. By doing so, it allows the use of a gapless L shaped compression ring to be implemented right to the top of the piston. Therefore ring flutter is reduced or even eliminated. The main source of hydrocardon emitions is also reduced as the Crevices – these are narrow regions in the combustion chamber into which the flame cannot propagate because it is smaller than the quenching distance.
    Crevices are located around the piston, head gasket, spark plug and valve seats and represent about 1 to 2% of the clearance volume.
    The crevice around the piston is by far the largest, during compression the fuelair mixture is forced into the crevice (density higher than cylinder gas since gas is cooler near walls) and released during expansion.
    The Beare head eliminates most of these Crevices.
    The valving is really piston porting augmented by disks and or reed valves. First the upper piston opens the exhaust ports. No other ports are exposed for 20 to 30 degrees to allow for a blowdown period. When the intake ports are exposed the reed valves prevent backflow and the intake disk is blocking its port. The exhaust stroke continues and towards TDC the exhaust disk begins to close its port and the intake disk begins to open its port. The intake reeds open whenever pressure differentials between intake manifold and cylinder allow. The disks are set in timing for the desired overlap. The exhaust system design plays a large part in evacuating the cylinder and starting the intake, as the ports are fully open at this stage.
    The exhaust disk closes and intake continues.
    The upper piston closes all the ports at aprox 60ATDC and compression begins. I have found it to be most advantageous to retard the upper piston in its relationship with the main piston by between 10 and 20 degrees to have peak cylinder pressure at the upper pistons TDC or aprox 15degs ATDC ignition timing advance seems to be best at aprox 25 degs advance.
    The cycle has some similarities to the Miller and Atkins cycle in that the intake volume is less than the expansion volume.




    further development
    To help keep a cap on power and, hence, speed, the MSMA has decided to propose a reduction in engine capacity from 990cc to 900cc. "The intention is not to reduce performance but to prevent a continuous improvement in speed and lap times," according to the press release.

    2004 2007 weight changes
    2 Cylinders 135 Kg 133Kg - -2Kg
    3 Cylinders 135Kg 140.5 Kg +5.5Kg
    4 cylinders 145 Kg 148Kg + 3Kg
    5 cylinders 145Kg 155.5 Kg +10.5 Kg
    6 cylinders 155Kg 163 Kg +8Kg


    The proposed changes to the rules also affect the minimum weight standards, adding more weight to engines with more than two cylinders from 2007.


    The proposed changes above may indicate the technical direction that some manufacturers are pursuing for the future. As Honda is the most powerful voice among the companies, it is interesting that the proposed minimum weight for five-cylinder machines, such as the Honda RC211V (and Proton KRV5), has been increased the greatest amount. This may indicate that Big Red is already working on new engine configurations and is looking to abandon the V-5.

    And, as two-cylinder bikes are the only ones to get a minimum weight decrease, might we see the introduction of a 900cc MotoGP V-Twin? If so, it wouldn't be as powerful, no doubt, but it would enjoy nearly a 50-pound weight advantage over a V-5-powered machine. And, as a Twin would have a 66-pound advantage over a six-cylinder-powered bike, it looks like the rumors of a Honda V-6 will not be fulfilled.

    The MSMA is also looking at perhaps reducing the 2005 rule for a 22-liter fuel tank capacity (down 2 liters from current rules) for the 2007 season.

    The introduction of 4-stroke machines to MotoGP has resulted in a huge amount of newfound interest in the class. Now, with revised regulations again on the table, the series might get even more interesting.


    The Testastretta engine fitted to the Ducati 998R 2002 version, the bore is 104 mm.
    Unfortunately, such a large bore currently causes combustion problems with dramatically decreased efficiency.
    This stems fundamentally from the need to augment the injection advance and from the worsening of the "shape factor" of the combustion chamber which, with the reduction of the bore/stroke ratio, becomes ever broader and flatter. The "shape factor" is a critical synthetic value to check a combustion chamber's good operation, and a good indicator of its compactness and "thermal efficiency".
    It should be borne in mind that aspirated racing engines require rather extreme valve lift and overlap angles, therefore, cavities are made in the piston crowns to prevent contact with the half-open valves. The combustion chamber is therefore practically contained in the piston cavities, such cavities becoming bigger as the stroke/bore ratio decreases, which makes it hard to obtain the high compression ratios required by high specific power engines.

    The Beare sixstroke does not have these limitations because the main lower piston does not have valve cutouts and the combustion chamber is a compact design with squish contribution from both upper and lower pistons. The shape is much more like a fist than a flat hand hence thermal efficiency is high .
    Combustion chamber diameter oprox 75mm
    The main piston is lighter and stronger than the 4-stroke, because the lack of cutouts allow a thinner slightly domed top
    Malcolm does believe that the sixstroke 15kg weight advantage will be a major benefit for the Beare Sixstroke, much more so than the 30kg handicap enjoyed by Twins in 500cc twostroke racing. "Working on the assumption that all these four-strokes are going to make enough horsepower, 15 kilos is a lot," he says. It’s straightforward enough, the Twins will have a 10 percent weight advantage and force equals mass times acceleration, so it is a big difference.


    Sixstroke Beare 900cc Vtwin MOTO GP

    Bore 116.25 mm stroke 42.5 upper bore 82mm upper stroke 34mm
    compression ratio 12.25 to 1
    power 337HP @ 15000 RPM
    torque 74.6Ft/Lbs x80% x2 = 118Ft /Lbs
    piston speed at 18000 is 5019 Ft/min or 25.4965 Mtre / sec
    XL engine file
    Torque 101.2 NM or 74.6 Ft /Lbs discount by 20% and multiply by 2 for twin cylinder is 118 FT/ Lbs
    6 port design with 3 exhaust ports leading to a rotary disk, 3 intake ports,One intake rotary disk and 2 reed valves with air assisted injectors. 2 or 4 10mm plugs per cylinder.
    The port area is oprox 20% to 30% more than a 4 valve head
    Results of XL file sixstroke touque calculator

    Based on Dual Cycle
    Total Torque
    Fourstroke 62.00

    Main Top
    66.05 35.15 101.20

    Increase in torque 63.23%




    Things are a little more complicated than you would expect
    During the intake stroke the main piston is increasing the cylinder volume while the upper piston is decreasing the volume (half of its stroke) so the net change in volume is +722cc . During the compression stroke the upper piston is still reducing volume (half its stroke) while the main piston is also reducing volume, net change -1082cc.
    During the expansion stroke the upper piston is increasing the volume (half of its stroke) while the main piston is increasing volume, also net change +1082cc.
    During the exhaust stroke the upper piston is increasing volume (half of its stroke) while the main piston is decreasing volume, net change -722cc
    if you add all the strokes together and average them you get 900cc
    The story changes again when you phase the coordination of upper and main pistons but the average remains constant.
    The combustion chamber is only aprox 75 mm in diameter maybe 2 plugs will be OK.
    http://www.sixstroke.com/
    malbeare
    Last edited by malbeare; 02-10-2007 at 01:38 PM.

  12. #27
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    Quote Originally Posted by malbeare
    The proposed changes above may indicate the technical direction that some manufacturers are pursuing for the future. As Honda is the most powerful voice among the companies, it is interesting that the proposed minimum weight for five-cylinder machines, such as the Honda RC211V (and Proton KRV5), has been increased the greatest amount. This may indicate that Big Red is already working on new engine configurations and is looking to abandon the V-5.
    No, Ducati will ahve bleated again and like 'other' Itlaian racing firms has a loud coive in the international forums.
    Honda have variants of the V5 engine puisign over 250bhp and Ducati know they can NEVER match that in a V twin or V4 configuration aso ahve managed to get an inordinately high weight penalty onthe V5 to pull Honda back the furthest.
    What will happen - as it always has - is that Honda will respond and Ducati will again end up a has-bean in the world of MotoGP.

    Thanskfully in WSB the restrictors on the Suzuki's ahve finally been increased form the timy openings Ducati fought for to keep their V-twins winning. NOW it's a well balanced race with Honda, Yamaha and Suzuki fighting for places in the first races and the Ducatis now running adrift as they can't get the same usable power out of the desmo engines as the others can oiut of I4s.

    DUCATI have distorted motor racing for the last 10 years on the world circuits. As evidence I cite the REAL races in Isle of Man and the NorthWest200 in Ireland where the limits are engine capacity and that is IT. Get the most from 1000 cc and race. Ducati's dont' win then
    And, as two-cylinder bikes are the only ones to get a minimum weight decrease, might we see the introduction of a 900cc MotoGP V-Twin? If so, it wouldn't be as powerful, no doubt, but it would enjoy nearly a 50-pound weight advantage over a V-5-powered machine. And, as a Twin would have a 66-pound advantage over a six-cylinder-powered bike, it looks like the rumors of a Honda V-6 will not be fulfilled.
    Well if it ends up with Ducati's having the huge benefits from the days in WSB when they had 1000cc bikes racing against 750cc bikes it will either be the demise of the series oor the demise of real racing - as Honda proved when they showed they COUDL do a big v-twin to fit the Ducati rules but preferred to show that V-twins were dead ends.
    The introduction of 4-stroke machines to MotoGP has resulted in a huge amount of newfound interest in the class. Now, with revised regulations again on the table, the series might get even more interesting.
    More ?
    I t has ALWAYS been interesting - unless you were a died-in-the-wool Ducati bigot

    Intersetign stuff on the beare engine, but jsut as they did with rotaroies, they will have to tweak the formula for equivalancy until it's a good match. So just as the Norton Rotaries had their "day in the sun" and won everthing, so may the Beare engines until the equivalency gets worked out and the limits tweaked to provide a match. HOWEVER, if Ducati can benefit from it, then it will no doubt be tweaked in their favour and nobody outside the racing circle will know about it.

    I used to love hearing Ducati guys talk down the pub how much faster 'their' Duc was because Ducs beat the rest on track adn they did not even know the Ducs were allowed to run 1000cc ( and did ) against the 750cc rest And in the last few seasons the BIG restrictors on the Suzukis wre the only reason Ducs won - and hence why most teams wanted to run Ducs to take advantage of the (mis)rules
    "A woman without curves is like a road without bends, you might get to your destination quicker but the ride is boring as hell'

  13. #28
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    Far out Matra.... you lost me at "No,"
    The Datto will rage again...

  14. #29
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    This isn't the first time I've heard about the 6-stroke idea, and it does interest me...
    An it harm none, do as ye will

    Approximately 79% of statistics are made up.

  15. #30
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    Quote Originally Posted by Blue Supra
    Far out Matra.... you lost me at "No,"
    Jeez, my typing's getting worse - that won't have helped
    [ Note to WOUter, PLEASE can we have a spell checker ?? ]

    Simpler answer.

    No. Ducati are cheating b*****ds. Honda have a numebr of optiosn to respond if needed. Ducati are cheating b*****ds. They may well run an engine configuration to gain and avanatage in the rules. Ducati are cheating b*****ds. They'll get caught in the end and everyone will laugh - again.
    Ducati are cheating b*****ds and fool people thinkign their machines are faster when really they're only bigger or less restricited. Ducati are cheating b*****ds.

    Does that help BS ???
    "A woman without curves is like a road without bends, you might get to your destination quicker but the ride is boring as hell'

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