Horsepower

First of all you are looking at this all wrong. You can’t get more power out of one engine than you can get out of another one exactly the same.

Here is the equation that defines power:
Power (kW) = Torque (N-m) × rpm / 9,550

You talk about the same redline and the same capacity. These are basically the things that will affect power. More capacity produces a bigger bang and more force (torque = force x lever arm) so more torque and in turn more power. Higher redline just means it is producing the torque at a faster rate so more power again. Just like a 2 stroke firing at every 2nd stroke and a four stroke firing every four the 2 stroke produces its torque at twice the rate.

This is all very simplified and perfect world examples to give you the basics.

 

top speed is mainly defined by your gearing.
so a stock FZR250 in 6th gear doing 18.5k rpm will do something like ~190km/h (don't know exact, sorry).

But change the sprockets, or the gear ratios and it might only do 160km/h... or you could make it do 200km/h + ... all at the same RPM.

But just remember how gears work. The bike with a top speed of 160km/h will get there much faster and much more easily than the stock bike: this is because the gears and sprocket ratios provide more torque / acceleration.

A FZR250 geared for a top speed of 200km/h+ may never actually get there. simply because the gears don't provide enough torque to overcome the wind resistance at such high speeds.

So generally you pick your sprockets (and gears if you have the dosh) for the track that you're riding on. On a tight, windy track with a short straight you would be more concerned with acceleration than top speed. But on a lengthy track with long sraights you would be more concerned with top speed.


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knowledge complementary of Gran Turismo, and may have no reflection on reality.
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As mentioned by Casso and Ciaran, engine HP and gearing will make a difference but over gearing will result in not getting enough torque at the back wheel to get optimum speed. Ideally with correct gearing max speed should be obtained at the engine rpm that max HP is achieved.

In a nutshell, the maximum speed you get is when the the amount of torque at the back wheel is equall to the amount of resistance encountered in forward motion. i.e. wind drag, tyre drag, bearing losses etc

 

ok. i can see what your asking. if you remove wind resistance and just work on ratio's. more power or torque wont alter how fast you can go in any gear so that means your top speed wont change either. if the "redline" stays the same the gearing will be the same. if you increase your compression ratio and "tune" your bike or add a turbo (not easily done on a fzr but work with the theory) you can get more power and keep the same redline. engine revolution (as long as there is full contact on the clutch) will dictate the speed, more power/torque (they go hand in hand mostly) will help you get there faster. so to review! power/torque means faster excelleration but unless you change your gear ratio's (which can be easily done) your bike wont be able to go any faster.

 

I try and stick to SI units, the metric system isn’t new and is pretty much the international standard now.

The trouble comes with horsepower when you don’t know the difference between bhp hp ps, metric is just a better way to go.

 

Bah!!! metric, smectrics

 

Is bhp just 2x hp eg 50hp is 100bhp ? and ps Ill need to ask dad about that one.

 

Good old kilowatts forever ????
('')('')

 

Crazy Americans. <!-- s:lol: --><img src="{SMILIES_PATH}/icon_lol.gif" alt=":lol:" title="Laughing" /><!-- s:lol: -->

Believe it or not PS is a sort of metric horsepower, well that was the theory.
1 PS = 0.9863201652997627 hp (SAE)

Bhp is just a hp reading measured with a brake dynamometer and is considered a true reading. When it comes to cars and bikes it could be taken at the rear wheel, fly wheel and just about anywhere in between but most makers don’t tell you where.
1 hp (SAE) = 1 bhp

When you get a hp or bhp reading about a car or bike it is kinda useless unless you know where the reading was taken and under what conditions.

 

So what your saying is that 1ps is just about 1hp and 1hp and 1bhp are the same?
1hp = 0.746kw

 

That is correct.

 

Thanks for that.

 

I always thought BHP was brake horse power whilst HP was just horse power (as in from the flywheel).

Here's the conversion chart...
Mph to Kph 1.6093 Kph to Mph 0.6214
Miles to Kms 1.6093 Kms to Miles 0.6214
Bhp to KW 0.7457 KW to Bhp 1.3410
Bhp to PS (hp DIN) 1.0139 PS (hp DIN) to Bhp 0.9863
PS (hp DIN) to KW 0.7355 KW to PS (hp DIN) 1.3596

 

Bhp is brake hp measured with a brake dynamometer. One or the other aren’t measured at any strict location such as the flywheel.

This link will tell you all that you ever wanted to know about the subject.
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