Does anyone know for certain what the percentage of power loss is from flywheel to wheel on a standard tranny R56? Some have guesstimated it's "about" 12-13% on the MINI. Asked two dyno techs and they said they'd never seen or heard of any FWD car going below 15%. Not that it really matters, but whose right?

 

15% for a FWD? wow.. that's rwd territory

usually i heard it's 10-12%

especially modern day FF cars.. with higher effeciency internals and oils..


the only way to be sure is to use a rolling road that measures the WHP and then on the run down calculates the drivetrain losses as well..


but if a FF is 15% then an FR would be near 20% and a 4WD would be in the 30+%!

 

I've heard 11-13%....

The thing about drivetrain loss though...it varies from car to car, from dyno to dyno. In addition, it is not constant throughout the rev range...it increases as RPM increases...but not proportionally. Drivetrain loss is greater at higher RPMs, than lower. Trying to calculate drivetrain loss is pretty useless, so you shouldn't worry. What matters is what is getting to the wheels, and the delta's you're seeing from stock to various mods.

The only true way to calculate your drivetrain loss is to run you car on a chassis dyno, and then run the motor on an engine dyno. You can come close to figuring a rough estimate if you put your car on a Maha dyno though...they are used heavily in Europe and are highly accurate. They will actually calculate drivetrain loss for every run that the car does. And it will plot drivetrain loss on the dyno graph for you. After a run is complete, and throttle is lifted off...the car is left in gear and the dyno slows the wheels down and can get a pretty good estimation at drivetrain loss.

They are pretty rare in the US and very $$$....but there is a Maha here in Phoenix, AZ @ Goodspeed Performance. They are awesome dynos...

 

even switching between different fluids in ur Engine/tranny/diff

can add/remove power u see at the wheels!

 

I would think the driveline loss on the 2nd Gen Minis would be less than the 1st Gen's because of the extra HP it takes to turn the supercharger pulley. 15% is generally given on the R53.

 

http://www.modified.com/tech/modp-10...oss/index.html
This should help you out a little bit in figureing it out.

 

Thanks a TON Porthos. Should'a known this was too complex to be covered by a single number of any kind. Guess I'll just stick to my butt dyno telling me my new RMW tune makes the car go like stink, LOL.