What is the difference between torque and horse power from the rider's perspective? And what is the "b" in bhp stand for? thanx

 

Torquier bikes will get you off the line quicker, but this phenomenon only lasts so long. As the revs build, high horsepower bikes will out accellerate high torque bikes. Big twins tend to make a lot of torque, and fours make a lot of horsepower. Thus, in a drag race, a Harley may keep up with you or even get ahead of you for the first 100 feet or so, but after that the race is over.
BHP means Brake Horsepower.

 

+1 Paco
I have a buddy with a 916 Ducati - outruns me for the first 100 feet or so, unless I wind the revs up and dump the clutch, then it's no contest either way. Over any real distance, BHP will win over torque - the trick is to find a balance between the two.

 

OK. Here we go.
Power is in modern time measured in watts (or kilowatts) but we all like to use the old formula of horsepower for caparing (HP=Kw*1,36).
What an engine produces is just torque (nothing else), in a modern country (sorry US/UK people) measured in Nm. To calculate the figure of power you take the torque and engine-rpm like this:

Torque: in Nm (Newtonmeter)
Engine speed in Rad/s (radians/second): one revolution is 2*PI radians=6,28
Convert rpm to rad/s like this: rpm*6,28/60=radians/s
100Nm at 6000rpm gives: 100*(6000*6,28/60)=62800watts, or 62,8Kw, which is the same as 85,4hp.

Just note that the max torque is lower in rpm than the max power, so 85,4hp is just the power at that particular rpm, not the max power. But at max power it probably produces less torque because the rpm has increased more than the power has.

A modern engine which reaches 100% fullness can produce 100Nm/litre (enginesize). Some good engines can actually reach a little bit above 100% (RAM air, good porting or other inventions) and therefore produce a few % more, but some normal engines produces a bit less than 100%. That means that a 600cc can have at most 60Nm (+ some %) torque. Good to know since if specs on bikes sometimes are exaggerated by manufaturers.

Since the torque is depending of rpm it can be raised by gearing. Double the gear ratio and you also double the torque. That is why a high power bike with less enginetorque ALLWAYS will outrun a high torque bike with less power. What really counts is the geared rear wheel torque.

 

WOW!!! Now in spanish por favor.....just kidding (great explanation)

 

I'm a little frightened. I came close to understanding what H-H wrote.

 

the longer you can keep your valves open in an engine and the faster you can open them (i.e formula 1 uses air to open engine valves) the more air you get into yr engine then you can feed in more fuel to make more power, however there is a fine line for valve overlap which can lead to engine distruction, cbr1000's quiet a short stroke for a large engine hence producing good horse power and not as good torque, that why duke's are faster at slower speeds. ...... think ive just confused myself

in short, the more power you have u loose torque (turning effort) and the more torque you have u loose hp, power. the longer the stroke of an engine the more torque it will produce, the shorter the stroke the more power or rpm. my 2c

 

Agood example is if you drive a petrol and compare it to a torquer diesel in a car
the diesel will tow better and not be effect much by extra weight unlike the petrol, but the petrol will have more zoom.

ABlackBird will make more HP then a Nissan Patrol 3.0L diesel, but put the 1100 in the nissan,and Idon't see it working out some how, no grunt.

Does this help, or am I somkeing something.

 

Also wouldn't a inline-4 be more ballanced than a v2 or v4?
not sure about the east/west type engines like BMW's have on some of thier bikes

 

Not going to get into the whole Keith Black and Mr. Langerfelt argument about horsepower versus Torque you can't have one without the other but foot pounds of torque is what push your *** down the pavement horsepower is merely bragging rights. I'll take monster torque any day over horsepower, but you won't get one without the other

http://en.wikipedia.org/wiki/Torque