Horsepower and wieght

[Speed Demon]

I was wondering if someone could explain the way weight has an effect on horsepower

IE 2 riders on identical bikes (same HP & CC) but each rider weighing different weights say 1 weighing 60kgs and 1 weighing 100kgs.

So how much horepower does the 100kg rider give away to the 60kg rider
and how many 0.00 seconds would there be difference over a 1/4 mile given they both had perfect runs.

It would show why some 750cc riders with less horspower and weight beat 1000cc riders with more horsepower and weight down the 1/4 mile.

Thanks

[TYSON]

Here's one link that tries to work it out, it assummes that everything is 100% traction, no wheelie etc

horsepower calculator for motorcycles et calculator

[quattro750]

sounds like someone now realises that physics might actually be useful^_^
to simplify F=ma +cv + kx
notwithstanding losses and lack of an ideal world, horsepower stays constant at constant revs. force changes when you change gear but we will assume for a moment that force is constant. there is no elastic band holding you to the start line so the kx term drops out. leaving you with mass times acceleration and drag times velocity. if you at a standing start v=0 so the dominant factor is mass IE if F is constant, accelaration goes up as m goes down and vice versa.

however as you accelerate v goes up and the second term (cv)starts to chime in which lowers the first term (ma) until at some point the second term dominates and the coefficient of drag governs. this implies that at the start weight makes a difference but somewhere down the strip drag/friction takes over and weight has little influence.

this is demonstrable by the fact that a bike can outgun a car early in a drag but struggles further down when the car's better drag coefficient takes over.

to do the numbers requires a younger geek than me

q

[stone]

Interesting, I was going to say somthing along the lines of....

Oi you UNI gitts,Build us an equation..... LOL

How much is 5/8th's of fuck all in pounds?

[Taylor]

0.4536 pounds to the kilo

[Barfridge]

Taylor, you just don't get it, do you?

And it's actually 0.4536 kilos to the pound

[Taylor]

Right, brain-fade.

[I Like ( . Y . )]

geez only 127 RWHP with my fat arse on my bike, spose to be able to make an almost flat 10 second run.....never gonna happen

[Speed Demon]

Here's one link that tries to work it out, it assummes that everything is 100% traction, no wheelie etc

horsepower calculator for motorcycles et calculator

Given that perfect run on my new busa and weighing in at 803lbs 240kg bike and fuel 125kg rider with approx 183 RWHP i got a 9.5sec pass though i couldn't see it.
i can have some fun with that calculator

[muz]

an interesting part of tysons website is that a 20 pound drop in weight gives you the same time as an increase of 5 HP

[aussiezx12]

Calculations for my bike show a 8.78 secs @ 155 MPH. Im not far off that

Lots of differences between my bike and a streeter though.

[Tenchi]

BWAHAHAHAHAHA... oh... oh... that's hilarious... apparently I can run sub 14's on my ZZR250.

I know for a fact that it will not do less than 16s, even with a slightly lighter rider than me, clutchless perfect shifting, so on and so forth with the current gear ratio.

[TYSON]

^^ have you been dragging long? I'll assume you put a lot of R & D into working out that the clutchless shift is perfect... hahahaha

[sathid]

Remember people, that the calculations assume no slip, and you are not adding an entire power/torque curve, so I'm guessing it assumes you are either using max power the whole way down the strip, or it calculates an estimate of average power, given your maximum.

Not to mention that there would be very few people here who would know their bikes actual power output (which can differ from what the dyno reads) or their bikes exact weight.

Far too many assumptions have to be made for that calculation to be accurate for everyone (anyone) with such limited supplied data.

[Eukanuba]

someone wanna explain this to cowgirl..

I tried to tell her, that my 110kilo ass.. against her ( assuming 60-70kilo ) frame.. would be of no comparison - hence her beating me by 2 seconds on the 1/4 mile.. when i had the cbr 250 against hers...

All would be equal - if you put a 40kilo bag of spuds on the bike.. and weigh it down like a jockey with a weight penalty ^_^