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Discussion Starter · #1 ·
I am a bit confused....

So hp is horse power at the flywheel
and whp is horsepower at the wheels...

Here is my problem:

The gearbox is a torque multiplier...so surely that multiplication would be picked up by the dyno...
... so on a gsr 2nd gear should be roughly 8x more torque at the wheels than at the fly....so 8x fly torque x rpm at the wheels for whp.

but its clearly not the case....so what is going on?

does the dyno bypass the transmission or does it just take the gearing into consideration?
 

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The transmission doesn't make more hp....it just multiplies by how much the gears are moving = speed. You can't make horse power by having different sized hears, but you have control horse power by changing gear size to give you different speeds/torque...I think that should help alittle.
 

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Energy is used up in moving the tranny, driveshafts, wheels, ect. This is known as paracitic loss or drag losses. This is why engine's will "make" more HP at the flywheel than the wheels. This is also why most dyno runs are made in 4rd gear where it's the closest to a 1:1 ratio with the engine.

A 1st gear dyno run should make more HP than a 3rd or 4th gear run. It takes less effort to spin the wheels in a lower gear than it does in a higher gear, thus a higher reading but with an identical power curve. More accurate? We already know how far dyno numbers get us here. I might be able to dig up some old dyno sheets where 3rd and 4th gear pulls were made.
 
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