Drivetrain Losses??

[itsallyellow]

What would we say is a fair percentage for drivetrain loss in power on a cerb?


I know lots of tuners use different amounts 15% up to 25%

What do you think?

Mike

[Brummmie]

20% i reckon is fair.

[BCA]

meh.

Edited by BCA on Wednesday 15th April 15:19

[itsallyellow]

BCA said:

meh.

Edited by BCA on Wednesday 15th April 15:19

???

[diycerb]

itsallyellow said:

What would we say is a fair percentage for drivetrain loss in power on a cerb?


I know lots of tuners use different amounts 15% up to 25%

What do you think?

Mike

Can it not be measured on a dyno

I thought you come off the gas and put your foot on the clutch at the top of the rev range, the car then 'coasts' down, while the dyno measures the resistance applied by the drivetrain. Sort of a dyno pull in reverse.

Rich.

[itsallyellow]

diycerb said:

itsallyellow said:

What would we say is a fair percentage for drivetrain loss in power on a cerb?


I know lots of tuners use different amounts 15% up to 25%

What do you think?

Mike

Can it not be measured on a dyno

I thought you come off the gas and put your foot on the clutch at the top of the rev range, the car then 'coasts' down, while the dyno measures the resistance applied by the drivetrain. Sort of a dyno pull in reverse.

Rich.

Yes you can, however i havent. I would assume all cerbs would be similar though? Has anyone done this?

Mike

[BCA]

I had put something, but left it as it'd cause a few questions that I am not sure one of you would want to answer. So left it be.

As for losses, an average Cerb loses all that my tweaked smart ever produces.

[HarryW]

60 - 80 hp perhaps, as a percentage 15 is about there.

[ridds]

Usually assume 15% for transverse and 20% for longitudinal mounted. Slight increase due to having to pass through 90 degrees at the diff.

Coast down losses imho are never realy that good. Gearboxes respond very differently when driven by the engine or via the road wheels You running on teeth that don't usually take the load (the backs) plus everything is loaded differently.

Only true way is to run the engine on a dyno, then chuck said engine in a car and see how it performs then. Even that way you can suffer issues with differing oil temps, tyre temps, tyre pressure and tie strap tightness. The there's the matter of single or twin rollers.....

Simply it's a nightmare. Best just to stick to wheel figures.

[Vixpy1]

Depends on the type of dyno

[ridds]

That has to be the shortest reply from a dyno operator on this subject ever.

[VPower]

From my pre and post re-map runs on Austec rollers it was 22.4% before and 22.2% after.