BHP?

[Davel]

I'm confused about this figure.

Do I assume that say a 650 cc bike with more BHP than a larger engined bike will be faster, or is it not just down to BHP?

Sorry to sound thick.....

[barry sheene]

It's down to the weight and torque characteristics rather than pure bhp.....

[Incorrigible]

Peak BHP has little to do with power across the rev range - which is waht you need accelerate

The important bit is the area under the torque curve for the rev range

Do a search on the "engine" forum there's fg loads of discussion about it

[andygtt]

AS said there is Loads of talk of this on the Engine forum....

BHP is pub talk, so many other things effect performance its mindboggling.

Anyhow to add to your confusion BHP is only a calculation of torque x Rpm.

[SirPsycho]

Davel said:

Do I assume that say a 650 cc bike with more BHP than a larger engined bike will be faster, or is it not just down to BHP?

No-one has yet mentioned it, but aerodynamics are gonna play a big part here also.

[rsvmilly]

Davel said:

Do I assume that say a 650 cc bike with more BHP than a larger engined bike will be faster, or is it not just down to BHP?

With weight being similar;

The larger engined bike would probably have more torque so would be faster on the road (when high revs are not so essential).

[barry sheene]

rsvmilly said:

The larger engined bike would probably have more torque so would be faster on the road (when high revs are not so essential).

So a Harley is going to be quicker than a ZX636, I don't think so......

It depends on where in the rev range the torque is delivered........

[rsvmilly]

I was being oversimplistic.

I had things like ZXR1200s in mind when I came up with that example.

And besides, you're implying Harleys are bikes (runs for cover)

[barry sheene]

rsvmilly said:

And besides, you're implying Harleys are bikes (runs for cover)

Oh yeah, silly me

[dannylt]

What revs do you actually like using on the road? If you're not happy doing 14000 constantly on a 600 to get that peak bhp, then down at 9000 you'll only have 80bhpish. So if the 1200 has 80bhp at 5000 revs it might suit you better. If you like thrashing it, the 600 will be more satisfying. Obviously this is ignoring weight & aerodynamics.

[bennyboysvuk]

On the whole, the more bhp, the quicker the machine will be.

I have an SV650 with around 70hp. I also have a GSXR600 with around 100hp. The SV weighs about 5-10 kg less than the GSXR and both have around 45 lbs-ft of torque, but in a straight line the GSXR will absolutely annihilate the SV650. So there we have it.

[RichardD]

dannylt said:

What revs do you actually like using on the road? If you're not happy doing 14000 constantly on a 600 to get that peak bhp, then down at 9000 you'll only have 80bhpish. So if the 1200 has 80bhp at 5000 revs it might suit you better. If you like thrashing it, the 600 will be more satisfying. Obviously this is ignoring weight & aerodynamics.

Yes, plus I also see this as when riding normally and what happens when you want sudden extra power. A smaller bike that gives the same bhp but needs more revs will require a changedown or two, but the bigger bike is ready.
For a while I made the mistake earlier in the year when following the most senior police motorcyclist in the area (doing a "bikesafe"), following his large Honda on my ZX636 whilst in top gear