OK - question for ya. What are the typical drivetrain losses for a scooby on a dyno?
Lets say a car makes around 260 bhp at the flywheel - roughly what would this give at the wheels.

Si.

 

Stripey,

mine made 270bhp last week but only 180bhp at the wheels. Feels nice on the road though!!

 

I got 257BHP at the flywheel, and 175BHP at the wheels last time.

This was a 99MY UK Turbo with various attachments :-) Though nothing modified on the transmission.

Tyre pressure can make a big difference, as can the wheelbase to which the dyno system rollers are set.

Hope this helps

Steve

 

Jeez, I was expecting some big losses, but these are even higher than I thought.

No wonder you guys aways quote flywheel figures down the pub.

 

Have a look at the dyno site, (click link at top of page) you will see a wide range, cars with the lockable centre diff lose less ... for the rest its higher and is just as dependant on the rolling road roller spacing, tyre pressures, suspension geometry etc as anything else.

 

Bob Rawle said
<<is just as dependant on the rolling road roller spacing, tyre pressures, suspension geometry etc as anything else.>>

OK, so if the RWP is measured directly, and the losses (and therefore calculated flywheel power) is affected by so many factors, how come everybody on this list always quotes flywheel figures.
Surely they are a nonsense, and we should all be talking directly measured rear wheel figures?

Si.

 

Since a Scoob is all wheel drive ... do you own one ? Common sense should tell you that the rollers measure the drive train losses for each car and add to the PAW figs ... therefore it is better to quote flywheel although IMHO rolling roads are good for comparative measurement and pub talk, the only real way to measure an engine is using an engine dyno.

 

<<the rollers measure the drive train losses for each car and add to the PAW figs ... therefore it is better to quote flywheel>>

I understand how the dyno measures the losses, but I still don't follow the logic of why quoting flywheel is better - it's just adding further margin for error into the equation IMO.

<<although IMHO rolling roads are good for comparative measurement and pub talk, the only real way to measure an engine is using an engine dyno.>>

I agree 110%.

Si.