> Have we kicked this horse to death yet, or is it still twitching?
>
Yes.:-) I was trying to think of the source of confusion here and it may have
to with the following.
A very simple equation for determining force available for acceleration is...
F = torque * overall gear ratio * efficiency / wheel radius
Now, the same equation can also be represented by...
F = power * efficiency / vehicle speed
...where power = torque * rpm, so F changes to ...
F = torque * rpm * efficiency / vehicle speed
...where rpm = velocity * gear ratio / wheel radius, so F changes to ...
F = torque * velocity * gear ratio * efficiency / (wheel radius * velocity)
which reduces to (back where we started)....
F = torque * gear ratio * efficiency / wheel radius.
For *instantaneous* acceleration (all else being equal), torque is what
matters. Integrating that inst. acceleration over time will give you your new
velocity. So, as stated by others and I agree, it's the area under the torque
vs. rpm curve that matters for average acceleration. However, too many people
confuse the area with just looking at a peak hp number, which only tells the
story at one specific rpm. Locating that area higher on the rpm range allows
taller gear ratio choices to maintain equivalent ground speeds than a lower rpm
range engine, thus greater overall acceleration.
Funny thing is, I wanted to set Mike off with a specific theoretical statement
that would clash with general reality (though true) and it worked all too
well.:-) Then I get sucked into my own stupid argument. Ah well. We managed
to go back and forth making statements that agreed with the same physical laws,
yet also use words like "NO" and "WRONG".:-) Reminds me of Corvette's vs.
Miatas.;-)
-Andy
Do You Yahoo!?
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