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Thread: Influence of engine configuration over its performance

  1. #1
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    Influence of engine configuration over its performance

    Excuse my ignorance, but can someone here explain this to me.

    1st, let me limit what i mean by "performace" into:
    1. peak HP
    2. peak torque
    3. max rev
    4. powerband range (HP)
    5. torque range in powerband
    6. vibration levels

    The question is, given a fix amount of displacement (though varying bore x stroke), say 3000cc, which engine configuration (single piston, v-twin, v3, I4, v4, boxer 4, v5, v6, v12 etc etc etc) will excel in each category? which configuration will give the best compromise?

    why are v8's regarded as torquey?

    also, for the sake of argument, all engine will be naturally aspirated though any cam technology can apply (vtec, vtc, variocam, etc etc).

    am i making any sense?

  2. #2
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    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.

  3. #3
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    This is a VERY complicated issue, because in a perfect world, all the configurations should behave the same, but in real life, this is not even close to the truth. There are a lot of physical factors which alter characteristics and I can't even begin to get into them.

  4. #4
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    From what I have read, engine packaging for everyday cars are mostly influenced by packaging constraints, tooling and cost.

    However, for performance cars and racing cars, the engine configuration has something to do with the performance it delivers. Back in the days when F1 had a wider choice of engine configuration, it is said that V8's have the highest torque ratings, but lowest revs capability (thus lesser power) that's why they mostly exceled in twisty circuits (monaco for example). While a V12 is the smootest and where best suited for long straights (monza?) but suffer from to much frictional loses that's why V10's where the best compromise... I am just wondering why this is so?

  5. #5
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    ok ........for starters theres it no such thing as a V5 engine.....and everything else has been said that is in my vocabulary
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  6. #6
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    Quote Originally Posted by GTR Dreamer
    ok ........for starters theres it no such thing as a V5 engine.....and everything else has been said that is in my vocabulary
    I thought VW had a V5?
    An it harm none, do as ye will

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  7. #7
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    Quote Originally Posted by GTR Dreamer
    ok ........for starters theres it no such thing as a V5 engine.....and everything else has been said that is in my vocabulary
    Oh but there is. The new Jetta V will have a 2.5 liter V5 motor.

    http://www.motoring.co.za/index.php?...879&fSetId=381
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  8. #8
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    Honda's motogp contender is a V5... I think ducati uses a V3 or V2...

  9. #9
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    but how does that work? and whats the point?
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  10. #10
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    what's the point of what? a V5? I dunno, that's why I asked. There is a point, I am sure of that, since a top MotoGP contender like honda chose to do it... The same thing that other teams chose to go another route (Yamaha has an I4, Ducati a V2orV3?)... Obviously, there's a difference, but what? that's what I want to know. what's to compromise of going one way from the other...

  11. #11
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    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.

  12. #12
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    I can see why a V8 of the same displacement as a V10 or 12 would have more torque; to make up for the lost cylinders, there would probably be a longer stroke. Longer stroke = torque.
    An it harm none, do as ye will

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  13. #13
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    Too big an issue and most of it gets VERY technical

    To answer some, 'most' V8s are torquey because they are a long stroke engine. Long stroke produces torque, short stroke/large bore produces revs and power ( to a first approximation anyway )

    Differning V configurations allow the timing of the combustion cycle to be varied. This allwos an engine designer to balance out natural harmonics and to control te delivery of power. The latter point is a BIG issue in MotoGp as they have bikes weghing 100kg and a power of 250hp all going to a relativesly tiny contact patch on ONE wheel. So an engine that produces a constant high power by virtue of an equitimed ingition cycle measn it's harder to contrll the tyre breakawy. So originally Honda developed the 'big bang" V4 idea in the 60s where the iming means that the combuistion surge all come close together and then thre is a larger gap before the next set of cylinder combustions. This 'big bang' actually makes the power delivery on the bike easier to handle - the theory goes that the 'rest' in between allow the tyres to 'bite' again.
    The V5 in MotoGp has run with at least 3 different firing orders and timing to match the needs of the track and the rider. It was this fliexibilty that was reported one of the reasons for them going V5. MotoGP is more guarded than even F1 in engine technology so some of the information on different stroke and bore used for development arent' released. but Honda seemingly had MANY configurations of the same setup and producing up to 300hp if they wanted it ( it just wasn't controllable )

    Modern materials are enabling designers to return to engine configurations dropped in the past because of vibration, torsional stiffness and strength issues.

    THIS is going to be a long thread, that'll do to grasp just now
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  14. #14
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    Thanks for the great insight Matra!

    I did a bit of "googling" on motoGP engines and found this gem:

    http://www.maclean-nj.com/2002motogpengines.htm

    Then got interested with ducatis demo valves which i read more about here:
    http://www.ducati.com/bikes/techcafe...hnical&artID=2

    Anyway, hope to hear more insights...

  15. #15
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    Also, how's this for an engine configuration?

    http://www.revetec.com

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