is there a ruff figure on this, i think it's about 25% on a 4x4 saff...but what is it on a 2wd....just a laymans way of compairing and equalling out the two cars from atw to flywheel....cheers Pete

 

it means that in theory my cars faster than yours on the road

 

yeh...but NOT really...lol

 

Around 15% ish.

 

...cheers for the time u spent on that......

 

4wd losses can be much more than just 25%

 

When i had mine rolling roaded at a EA on a passionford day the difference was quite a lot...

Just looking at my graph difference between power at flywheel and power at wheels. It was over 105bhp different... (Stage 3 saff) fiqured about a 33.2% power loss through the transmission...

Shocking!

 

and.....well what then??????

 

...cheers for the figures

 

i'd say between 10 and 20 %, only real way to tell is take it to a good rolling road and have it measured.

my old cossie only lost about 30bhp
the new one lost around 80bhp

No real way to compare like for like unless both are run on the same set of rollers

 

i have just had a look at a power graph i had done at powerstation and there is a 148.3 bhp differance!!:0

 

....what power u running like...?????

 

Is measureing at the wheel power not usless? I mean it affected by loads of factore - tyre pressure etc, even the dyno operator moving about inside the car change change you readings.

I've always wondered why AVA use at the wheel power?

 

308bhp

 

OT here but relevant,is this why you hear about cars like Impreza's being beat by other cars once rolling becuase of Tranny losses?

 

The thing your missing is that 4wheel drive transmission is very old technology (Over 15years old)

And with scoobies/evo's etc etc they have had more money to invest/develop in a stronger and better transmission....

 

im still not a believer in the xx% lost through the transmission, surely a 400bhp car would lose the same amount as the same 300bhp car since they are both turning the same transmission load? meaning the transmission loss would be a set figure not a percentage.

yeah

 

so ii take it its the similar loses for an escos?

 

a rolling road or dyno is only as good as the operator..

 

Probably because it's what the rolling road measures, not guestimates...

 

Using 25% transmission losses, and a 350hp engine as an example,

25% of 350 is 87.5.

Watts = BHP * 745.7
87.5BHP = 65249 Watts.


Would that not render your gearbox and diffs a little bit warm?



Neil.

 

depends if you are talking about just the losses in the transmission, or also through the tyres to the contact patch of the road or rolling road (massive difference, particulalry if rolling road uses 2 small rollers )