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      06-04-2013, 03:31 PM   #76
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Drives: E92 M3
Join Date: Sep 2006
Location: San Diego, CA USA

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Originally Posted by CanAutM3 View Post
I beg to differ. Maximizing average power generated over an acceleration run is what needs to be done to optimize acceleration. Now there are several ways to calculate and figure this out and I agree that the method you suggest is one of the most straight forward ones.

The only difference between propulsive force and wheel torque is the wheel radius (this is pretty much a constant on a street cars, mybe not on a top fuel dragster though ). You need the engine torque curve and gear ratios to plot propulsive force vs road speed. Saying that torque is irrelevant is not really accurate.

You will find that when the force lines of two gears cross, the power generated in the lower gear is equal to the power generated at the higher gear at that speed. Thus maximizing average power.
I don't disagree with what you've said. It is a matter of simplicity and clarity.

Certainly wheel torque and propulsive force are related by wheel radius, which less dragsters remains close to constant. However, the further back we go in the drive train; wheel, driveshaft, transmission, crankshaft, etc. and the more you speak about torque (unless you are concerned about the strength and stiffness requirements of these components) the more torque becomes a bit meaningless. Clearly we agree that torque at the crank (without taking into account all gearing in the drivetrain) really tells you NOTHING about vehicle performance. Thus why stop at the axle! The simplest and must fundamental concept is indeed propulsive force.

Next, why worry about averaging when you can focus more simply about maximizing instantaneous propulsive force? It just adds conceptual and mathematical complexity that is not required to understand the issue to worry about averaging and/or power, the former technically requires numerical integration of a curve...

No worries, we're pretty well on the same page here.
E92 M3 | Space Gray on Fox Red | M-DCT | CF Roof | RAC RG63 Wheels | Brembo 380mm BBK |
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