BHP Reading of the Dyno

[Steggz]

Right i've had my 750 dyno'd with a race filter/ Runs sweet as anything now lol! However the Dyno read out was 66BHP which as it was on the rolling road was at the back wheel. Am i right in thinking the standard BHP (also 66) is read from the fly wheel? If thats so which i'm confident it is, do any of you know the ratio for these bikes in terms of what is roughly lost through the transmission...? I was thinking it cant be far away from the 900's power when standard?:mand:

Thanks for any reply's

Luke

[Gilps]

My S2r 800 reads 73.4 bhp with open air box and hi-flow filter, termis, cat removed and power commander. That's at the back wheel against a book figure of 77bhp, presumably at the crank. It was tested though with just 1000 miles on the clock. I think it has loosened up a bit more now so those figures may well be up. I guess it was probably around 70 before the mods.

[CK & AK]

about 6% is lost through transmission

[slob]

I was thinking it cant be far away from the 900's power when standard
Not a chance, and bags of torque less. It will however be easier to manhandle round corners than a nine. Pipes and filter are probably worth about an extra 5% when set up right. There's no substitute for cubes!

[Zimbo]

Until very recently, Ducati always quoted bhp as measured at the back wheel. Japanese manufacturers have always quoted bhp measured at the crank. A couple of years ago Ducati changed to fall in line with the Japanese etc, which is why the 1000cc aircooled bikes suddenly jumped from a quoted 85bhp to over 90.

[Steggz]

Hmmm and so the debate begins lol. I also posted something on the suzuki forum and big bob (legend and the font of most knowledge) seems to suggest a 20% reduction from crank to back wheel. I think it's safe to say its a back wheel read out i got based on the figures, it correct. But even 5 percent is squeezing 70bhp out of her. Not bad really

[Zimbo]

maybe, but power figures as taken at the crank are completely meaningless, it's power at the back wheel that counts. the original quoted power from the 750 (66bhp) is as measured at the back wheel, so yours with the race filter is bang on what it should be.

[Steggz]

well based on that still from a 12 year old motor thats good. Cant really fault it. Chances of the power being the same over that amount of time is very slight. Some of the rampaging italian horses do get lost along the way.....

[Zimbo]

I quite agree, it's proof that your engine is still in great condition! :cool:

[bod]

Remember though not all dyno's are acurate, go from one to another with the same bike and you can get sometimes quite different readings,best to get a reading done,do the mods then go back to the same place.

[gary tompkins]

Bod is spot on

Dyno's can vary a lot - as much as 15% is some cases.

It's well worth using the same dyno if you are chasing small power gains. You could visit a different center to see your motor drop in bhp, when it's actually producing more power due to changes you've made.

My mate Ian has been tuning his GPZ900 over the last couple of years, and spending a small fortune in the process. He always uses the same dyno for his power runs, but also said seat of the pants gives the best feedback for way motor runs.

Problem is it's a tad difficult to find somewhere to hold it flat in top gear, as it's well off the scale on the 150mph speedo :eyepopping:

[Mr C]

Id heard as much as 15%