Typical Rad transmission losses?

[fergus]

After having my 07 R1 engine tuned by Bob Farnham (to around 185 rwhp on his dyno = ~ 190 rwhp on the British Superbike dyno), I'm curious as to the transmission losses on a 'typical' Rad final drive (if there is such a thing as typical?!)

My mods include a skim, cam timing (std cams), full gas flow, thinner head gasket, a full blueprint and little else, other than a good setup with a Power Commander and a full Ti Akropovic system! No other major changes. 998cc.

This question arose after the 'Racing Query' thread mentioned someone had a 182 rwhp mistral tuned 1300 (IIRC), which I'm guessing means substantial transmission losses?

[RobC]

Depends on the type of diff you are running i.e. Quaiffe direct drive or chain. IIRC I used to work on around 16% loss through the drive train on "normal" cars.

[nick997]

Fergus - search back a few months and you will see dyno graphs of Darrens 1300. In fact I think Rob may have posted them.

[dsl2]

Fergus it was 192.22 RWHP actually!

Its suggested that for a Radical type installation of a bike motor running a chain & Quaife LSD that you allow for approx 12% losses, equating to my 1300 giving roughly 220bhp.

The losses for a Caterham type bike motor installation, with the two prop shafts / central transit bearing support / ZF plate diff is supposed to be in the region of 15%, equating to approx 235bhp from the 1397cc Mistral motor in mine.

Edited by dsl2 on Tuesday 20th October 21:42

[fergus]

thanks guys. I couldn't recall the exact figure when I made the prior post. Apologies if anyone got upset over this!