torque vs. bhp.

[Mikeylad]

A little question that has been puzzling me for a while.

I am looking for a neat, layman's definition of the difference between torque and 'power'. I understand how the difference manifests itself in the driving experience, but don't know exactly what it is. I partly remember an analogy involving a wishing-well and differing sizes of bucket and speeds of lift.

Have i made this up? Can anyone even phrase my question for me, let alone answer it? I'm going to go and lie down...

M

[Mikeylad]

ok, but what then is the technical difference between initially pushing off the blocks, and more generally 'accellerating'?

When does the one become the other?

I'm going back to lie down.

>> Edited by Mikeylad on Friday 28th March 20:06

[Mikeylad]

i was familiar with that part - the 'real-world effect' part - but am still unable to 'picture' the two. Is it possible to have an engine with measurable torque, but zero bhp, or vice versa?

[Mikeylad]

GarryM said:

Mikeylad said: Is it possible to have an engine with measurable torque, but zero bhp, or vice versa?

Don't think so as power is a function of torque. IIRC power(bhp) = torque x revs/5250. You can see from this that a high revving engine can produce high bhp without necessarily having high torque. Power gives you speed, torque gives you acceleration. Hope this helps.

That does help, cheers. Also raises another question though. if power is a direct function of torque, how come engines that produce similar power outputs at similar revs can have widely varying torque figures.

By your formula, wouldn't every car producing, say, 200bhp @ 6000 rpm have identical torque figures?

or am i a simpleton? be honest with me. please.

[mikeylad]

i think i might have started something i can't control.

am i right to think that all engine with matching power curves must by definition have matching torque curves?

i can't see any room in the formula for deviation. having said that, i can't see much of anything.

[mikeylad]

This is all good stuff guys, thanks.

Has anyone heard the wishing-well metaphor i vaguely remember or did i just make it up in a dream?

the lad

[mikeylad]

cheers!

[mikeylad]

mad dawg said: A bit late but here's my understanding:

torque (in lbs ft or Nm etc..) is a measure of an engines ability to do work

power (in hp or KW or whatever) is the rate at which it does the work.

simple as that!

so (assuming metric, probably wrongly!):

power is Nm/second

or not?!?

and what is PS? (besides a regional variation on BS!)