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Automotive Torque/hp philosophy (infinant gear ratio)

  1. Aug 19, 2012 #1
    I am still trying to visualize horsepower and torque seen on the racetrack, and its hard. Obviously torque is a component of horsepower. Without enough torque, a car would take forever to reach its power-band. With a lot of torque, but merely no horsepower, a car would have a very steady acceleration curve, however, it would be slow.

    so far correct?

    I hear the car guys talking about how torque wins the races, (which annoys the **** out of me) when in reality, the truth to that is that smaller engine cars have a shorter powerband, and it takes longer to approach that powerband, when compared to muscle cars, correct?


    What if in a completely theoretical situation, car had an infinitely variable gear ratio (such as a cvt), calibrated in a manner that kept the engine speed at its optimum powerband, regardless of the vehicle speed. So Im saying from a complete stop to a half mile, a vehicle goes full throttle while the computer adjusts the engine speed to remain at a constant rate.

    Would torque be utterly useless in this fairytale situation? Obviously with no torque, it would be theoretically impossible to get something moving. But with negligible torque, could a small sized combustion engine with a significant amount of horsepower be used to tug a tractor, just as well as a larger sized diesel engine with the same hp output? (taking vehicle weight out of the equation)

    This helps someone visualize that torque rating (on dyno sheets) is only useful for having a steady powerband for a duration of acceleration before changing gears. Which obviously on most production sports cars, is highly sought after.

    This theoretical situation could shut up the torque enthusiasts, right? Obviously its only theoretical, but if you want a real life application of this, its called a race transmission. Many top end race cars have transmissions geared so close that they are merely in there powerband 100% of the time. Rendering bottom end torque not that important.

    I MUST STRESS that I am only speaking relatively here. Its obvious with todays technology, performance cars need a good amount of torque to compensate for gear changes, ect. But consider the future, if we could design a continuously variable transmission strong enough to withstand lots of horsepower, and able to keep an engine at its optimum power band merely 100% of the time.

    Please correct me if i'm wrong, and I would love discussing this, further.
    Last edited: Aug 19, 2012
  2. jcsd
  3. Aug 19, 2012 #2
    Another person from a similar thread said something that I thought was interesting:

    Given a conventional geared transmission, supposedly best momentary acceleration is at peak wheel torque. This comes from F=MA, arranged as A=F/M. Acceleration is highest when force (torque) is highest.

    Based on this viewpoint, optimal average acceleration would happen if an infinitely-variable, lossless continuously variable transmission kept the engine at torque peak throughout the acceleration run.

    So to further reinforce my point, the optimal engine speed set by the theoretical governor would be set at the engines highest torque output, usually around 6-8000rpm in a smaller sized engine.

    So it doesn't matter WHAT the peak torque is, as long as you have enormous amounts of horsepower, and you can stay in that range between max torque and max hp, your vehicle puts out a steady and vicious acceleration.

    Acceleration is what racers want, as long as they have lots and lots of horsepower, and they can stay in their optimum engine powerband (at max torque output), engine torque is negligible.
  4. Aug 19, 2012 #3
    My god, not this again.

    Why do you keep making threads waffling on about the same topic? This is exactly the same as the last two topics you've opened.

    You set up a the single scenario where you can disregard torque output, and then try to extrapolate that to all situations. You also keep discussing torque and power as though they are in no way linked.

    If you have a question, why can't you just ask it simply. So it can be answered and then you can stop asking repeat questions.
    Last edited: Aug 19, 2012
  5. Aug 19, 2012 #4
    Thats only because Im trying to come to a consensus among people.

    I think I made 1 or 2 other threads about this, and that was several months ago, do you really loaf around the forums that much to give a f***? Cmon.
  6. Aug 19, 2012 #5
    The threads are virtually identical. Just from a 'forum cleanliness' perspective, it may be better to bump the existing thread. That way you don't get the same thing posted over and over, as people can follow the discussion and progress can be made.

    A new thread hits the reset button.
  7. Aug 19, 2012 #6
    When people re-quote 'power sells cars, torque wins races' and apply that to 'power is meaningless' most are misunderstanding a simple, but very eloquent phrase.
    The phrase actually means, peak values are largely meaningless. It's how the engine operates throughout it's range.

    Further to this, what you appear to discuss is engine operating range.
  8. Aug 19, 2012 #7
    ok ok ill give you that one, not a bad idea ill admit.

    I don't think they always misunderstand the meaning, but they limit their experience to traditionally geared transmissions, where nowadays aftermarket transmission suppliers are involving larger varieties of gearing/clutch setups. You can only argue torque theory so much, at least until someone shows up with a smaller engine that pulls harder primarily because of the high final drive and close geared transmission. While its certainly less common on the track, its still proving american muscle heads wrong.
  9. Aug 19, 2012 #8


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