Ducati Sporting Club UK > General > Idle Chat > BHP???

[bradders]

can someone please sort this out for me...
had a 'discussion' (read argument) today with a guy who insists bike manufacturers publish rear wheel bhp in their literature. Now I am sure most (especially Jap makes) use higher crank figs, but don't know if Ducati do as they seem to be about right on the bikes dynoed last week....help, I want to put him right tomorrow Also, what would 124 equate to at the crank??

Cheers
Paul

[gasmanrus]

hi paul, am sure jap manufacturers use crank figures. seem to remember a dispute between suzuki & ducati about bhp figures when the TL came out.
ducati claimed you couldnt accuratly account for drivetrain losses when measuring at the crank. (sorry,dont know what they would be but in mcn they claim the R6 puts out an optomistic 120bhp!!)

hope this helps with your discussion!!

russ

[Totto]

My 998Bp puts out 112bhp at the rear wheel dyno measured !
I think Ducati quote 112 bhp for my model !

[Scottch]

Paul,

Don't quote me.

Ducati do measure rear wheel BHP.

The Japanese manufacturers use an engine dynomometer (sp?) to measure the HP at the crank.

Ducati, also weigh their bikes half wet (oil, some fuel, coolant) where the Japanese weigh their bikes dry.

Again, don't quote me but I'm sure I've read all this somewhere before.

Cheers!

Scott

[skidlids]

My Genuine Ducati manual lists my a 916BP as 109bhp at the CRANKSHAFT and the 916SP as 131bhp at the crank.
Last week my 916bp recorded 104.8bhp at the rear wheel, cant say if the open pipes and chip have added much but normally I would be expecting drive train losses of around 6 to 7 bhp., My TL1000S made more power but was the best part of 80cc bigger and sported a full race system and BMC air filter, it also weighed a lot lee than my 916, but was physically wide and handled like a tea trolley when compared with a Ducati.
Jap bike bhp is always quoted at the crank by the factories from what I've read and I can quite believe 120bhp at the crank of a new R6, I have just picked up a year old GSXR600 with a tuned engine knocking out 116bhp at the rear wheel for which I have the Dyno graphs.

[Desmondo]

As far as I understand it, you've pretty much got it spot on Scottch.

[fodder]

An O ring chain alone will lose 10% of crank power, then the the condition of the sprockets and not to mention the lubrication and wheel weight.
As a guide, power at the back wheel is around 20% less than the crank.
So the R6 with 120bhp will lose 24bhp through the drive train and a more realistic figure of 96bhp appears.
Judge for yourselves.

[dickieducati]

i always thought you lost about 8-10% from the crank to rear wheel. maybe this is just on ducati's. thats works about right on my 999. 143 crank 132 rear wheel.

[Felix]

Take the case of the new ZX-10, R1, Fireblade all claiming 170 and 180 with ramair. When they measyred rear wheel horsepower they were all within about 5 bhp at just short of 150 bhp. A bit optimistic shall we say?

[Doyley]

But my bike is great what ever the horsepower it is, it certainly left a Gixxer thou strugglin round stonebridge island the other day, until we got on the long straight bit.