Hi guys, was wondering if you could help me with something thats been bugging me. Most Rolling Roads seem to produce accurate wheel hp figures however the transmission drag (or whatever its called) that is used to calculate power from the flywheel seems in most of the example's ive seen seem to be higher than id of expected for a fwd car, if youve had your octy on a Rolling Road could you post up the transmission loss recorded and where it was recorded at... i hope to be able to get a better understanding of what kind of losses are realistic and which rolling roads are optimistic.

cheers.

( i know no 2 cars are exactly the same but i figure the difference in transmission losses between cars will be close enough.)

This might be of some help?!?!

http://www.rhodribaker.entadsl.com/Cars/vrsbhp.JPG

mine showed total losses of 26bhp on a standard car (149bhp @wheels, 175bhp @flywheel, 180lb.ft. uncorrected at 30deg.C) recently on Slark Race Engineering's Sun dyno, which is considered to give as realistic a figure as you are likely to get.

cheers guys, anyone else been on other RR'ds?

seems 25bhp is right for transmission losses on an octy. thats lower than id expect but only by 5bhp. Main reason i ask is that i see footers all the time of members claiming to have 230bhp or close to it and when the whp is looked at its the same as mine...180.

181 bhp at the wheels and 193 at the fly thats with 242 lb/ft sooo 12 bhp lost that was at awesome gti:thumbup:

181 bhp at the wheels and 193 at the fly thats with 242 lb/ft sooo 12 bhp lost that was at awesome gti:thumbup:

At what rpm are those power and torque figures made? IMO the 12bhp losses are very unrealistic, and with that amount of torque the flywheel bhp should be more than that, unless the torque drops away very significantly..

I'm not commenting on a specific RR, but AIUI transmission drag is measured on the closed throttle run-down of a power run, so might vary from road to road (or even day to day, like power figures can)?

At what rpm are those power and torque figures made? IMO the 12bhp losses are very unrealistic, and with that amount of torque the flywheel bhp should be more than that, unless the torque drops away very significantly..

see for yourself tis the red octy vrs

Awesome GTI Store UK - Rolling Road

Awesome seem to show quite small drops between wheel bhp and fly bhp in my experience. My two car's results on their RR (diesels though):

...............................................torque.......wheel power......fly power

Fabia PD100 (with tweaks)............222ft.lbs..........113.................126

Octavia 2 2.0TDi (standard)..........264ft.lbs..........143.................156

I'd be interested to hear people's opinions on this actually, although the figures from my Octy would suggest their losses are not that far out as I wouln't expect a standard PD140 2.0tdi to get much more than what Awesome claim at the fly as standard.

see for yourself tis the red octy vrs

Awesome GTI Store UK - Rolling Road

some curious anomalies when comparing with the other octavias, most seem to be closer to the middle 20's, which is more reasonable. Presumably all the cars were run at similar speed in the same gear etc? It's difficult to explain a difference of 50% losses.. :confused:

this is an interesting read, from a guy who has a good reputation for knowledge in the industry:

Puma Race Engines Technical Guide - Transmission Losses - The Last Piece Of The Jigsaw

Puma Race Engines Technical Guide - Measuring Engine power - engine dynos and rolling road dynos

not sure all i know about mine is that it had 20k on it and has had the gearbox repaired a couple of weeks before as it would'nt go in to 4th without crunching

rest of the octys (someone will correct me if i am wrong) had higher mileage on them