MikeWS6

I was planning to hit the dyno soon but first I have a question. When trying to determine how much power your car makes at the engine do you simply take the rear wheel hp and multiply it by 100 then divide by 85 for an M6 car? 85 Would represent the 15 percent loss. Is it that simple or are there other factors involved? Say my car makes 320 hp. 320x100/85=376. Sorry if this is a dumb question.

adam1803

iTrader: (65)

Thats about the best way to estimate it. There could be more or less than 15% loss through the drivetrain depending on a ton of factors. There is no 100% accurate way to determine flywheel hp from rwhp.

MikeWS6

Thats what I thought.

Thanks

Dmoney

iTrader: (22)

When I use to get my car dyno'd at MTI, they use to put a formula on the dyno sheet to get your flywheel power. It was your rwhp/.88 for M6 and rwhp/.82 for A4. Example: mine is 472rwhp/.82= 576hp...............

MikeWS6

This way would be less than the other.

Chris Gage

iTrader: (18)

The only way to figure out the drivetrain loss by percentage for you specific set-up would be to dyno the motor and then get onto a chassis dyno. For 99% of the members on here, this isn't an option plus the change in wheatehr and other varibles would make that percentage inconsistent. SOme will say it can be as low as 12% other will say 15% and some will say 18%, which is a pretty big difference. Track times ar ethe best way to compare numbers though.

TappetHead

If you are in CA you could go to XS Engineering.
They have an Australian made DTS chassis dyno which has a drivetrain loss measurement function. They can measure the drivetrain losses and tell you exactly what the FW hp is.