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      11-27-2013, 05:28 PM   #110
swamp2
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Quote:
Originally Posted by CanAutM3 View Post
Sapper got it. The area under the torque curve has nothing to do with power. Torque and power only correlate for each individual RPM points on the graph.

Distance in the polar referential is rotations (rads, a non-dimensional unit; 1 rotation = 2 pi rads). So rotations in the polar referential is a "real distance".
+1

Lot's of internet car experts like to talk about good old "areas under the curves"...torque or power. They are largely meaningless physically but the point folks are trying to talk about is somewhat relevant. They are basically meaningless because in any accelerating vehicle rpms don't grow linearly with time and they way they do grow with time depends on gear and drag... Comparing two torque curves where one is always making more torque does indeed have more area under its curve of course said engine is also consistently making more power and that is what matters...

I think the confusion generally goes like this:

How quickly velocities can grow depends on the work done (ΔE = W, work-energy theorem). When forces vary work must be integrated. You can integrate F*v dt (power vs. time) or F dx (force vs. position). Both expressions contain force the instantaneous force applied to the ground depends on the engines torque. Q.E.D. let's just integrate torque (in some loose definition vs rpm) vs. the only thing we typically see torque plotted against - rpm.

To discuss anything in regards to integrating one must carefully distinguish between engine parameters (rpm, rotations, etc.) vs. "real world" parameters (time, distance, etc., these are what the car does, not the engine).
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Last edited by swamp2; 11-27-2013 at 05:33 PM..
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