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How much power is lost through the manual and steptronic drivetrains? 10-15% for manual? 15-25% for step? I know older automatic cars lose about 25% of the power from drivetrain loss, but was curious as to how E46's do.

Well, basically, what would a 325 dyno stick vs manual, and what would a 330 dyno stick vs manual, all cars being stock...
 

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I've heard (from Alex at Eurospeed Performance) to account about 15% loss for the manual and between 20-25 for the steptronic.
 

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Typically people use 15% for the manual and 20% for the auto. It's trickier with auto b/c the efficiency changes depending on whether the lock-up clutch is engaged.
 

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Is the calculation for torque same as horsepower?
thanks!
 

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All cars are underrated from the factory, insurnace purposes, never seen 25% loss on an auto. Does anyone make an aftermarket torque converter for our step trannys?
 

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BMW Manual are pretty efficient, the #'s i have seen for our cars are about 14% loss for Manual, and 21% loss for Auto
 
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