Rolling Road Results

[MrG 3]

What is the transmission loss for std a 205GTI 1.9? So for eg, if the rolling road result showed 130bhp is this normally at the wheels or at the fly?

 

Do the machines differ and give both or are they only able to give one figure? And am I right in thinking that when you do any mods its best to use the same RR for comparison results?

 

It's one of those Monday things that I think I know the answer to but not confident that I really do?

 

Many thanks

[large 33]

The 128bhp is at the fly wheel. I think the transmission loss is about 10-15%.

 

The RR only measurs bhp at the wheels then works out what it is at the fly wheel (when I say works out its more of a guess). That is why you should go by the at the wheels fig.

 

yes you are better off using the same RR.

Edited January 26, 2009 by large

[MrG 3]

Thank you Large, much appreciate the reply.

 

Clears some issues up for me.

[Baz 421]

Lots of different machines measure it differently though, there seems to be a generalisation that the loss is say 15% for a FWD car etc, which is bollocks! It's a minefield of questions with so many depending factors. DynoDynamics have spent years & millions on researching it all over the years, hence why they can claim to be the best in the business.

[VisaGTi16v 1]

Also places seem to use vastly different calculations for estimating the flywheel figure. Ive seen people on here boasting 10bhp more than me at the flywheel but their graphs showed 10bhp less at the wheels

[SPGTi 2]

Also places seem to use vastly different calculations for estimating the flywheel figure. Ive seen people on here boasting 10bhp more than me at the flywheel but their graphs showed 10bhp less at the wheels

 

I think this is true, dependant on the system I think some will show a "wheel" figure plus a "transmission" loss whereas other places seem to show "a measured figure at the wheels" plus an "overall loss" which takes into account not only transmission losses of the car but also losses from the rolling road itself. I have had a previous car rolling roaded at 2 different places before and the fly figure was constant but the "@wheels" was quite different.

 

 

Steve

[DRTDVL 4 1 Cars]

you have to factor in alot of things when tring to do flywheel power..

 

like oil vicosity- thicker oil is going to rob you of power in the gearbox, it's not easy