Drivetrain power loss?

[Samckitt]

What percentage of power is lost through the drivetrain? Tranny is an "LT1" T56, rearend is a GM 8.5" with 3.42:1 gears.

Thanks

[oestek]

We did a test years ago with a GS455 Buick, ran it on the engine dyno, then in the car with an M-22 on the chassis dyno. The engine lost 14% through the driveline. Autos claim more, like 17 - 18%.

[class67]

The general rule is 15% - 20% I believe.

[Vegas69]

Mine was right at 15-16% with a TKO600. You must have a engine dyno to compare the results. This crap of my motor makes 750hp when it really makes 650 is the problem with the huge drivetrain losses. On the flip side the factory cars can make more power making the loss look smaller.

[WS6]

15% for manuals and 20% for autos are the numbers used. Todd's right though, unless you dyno the engine first and then the car, you'll never know for sure.

[redhead]

I have not personally measured it but have heard that a gm 12 bolt rear is 2% more efficient than the ford 9 inch.
also in regards to manuals, a 5spd will be more efficient than a 6spd.
makes sense when you think about it, less gears to spin.

[79-TA]

Mine was right at 15-16% with a TKO600. You must have a engine dyno to compare the results. This crap of my motor makes 750hp when it really makes 650 is the problem with the huge drivetrain losses. On the flip side the factory cars can make more power making the loss look smaller.

Modern factory cars' flywheel horsepower is usually reported as SAE net, that is, with all of the accessories attached etc. so some losses are already accounted for. Correct me if I'm wrong, but I believe several engine tuners and magazines still report gross horsepower figures.

Drivetrain loss can be reduced with lighter compenents, less friction (which can come at the cost of diminished strength) and refraining from using nonsensically large wheels.