Timberwolf

I was helping a friend do some math for his downhill racing bike. We were trying to determine actual tq at the diameter of the tire based on length of the crank arm, gear ratio etc.

This got me to thinking...is the rear differential in our car a torque multiplier? In theory it would seem to be. But if this is the case, would doing a dyno with 2.73 gears and 4.10 gears make a significant change in RWTQ? And would that be in the actual numbers or just in the RPM range?

I guess the way I look at it is the dyno actually may "see" a big difference in tq from the low gears to the high gears, but compensates with inputs of final drive ratio (gears and tire size) in order to bring it back to a constant, comparable level...

Am I on track? If not, what am I missing?

dabear95

I believe that when you dyno a car you have to input your gear ratio to determine the amount of torque. The engine does not actually put out more power, it just puts the same amount of power down faster so you have to calibrate the dyno accordingly.


If you computed the numbers based on a 2.73 ratio when you actually had a 3.73 then the numbers would be inflated. I think. I have never been to a dyno with my car, and have only seen it once.


Jason