## Torque v Power

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• Torque v Power
• Gee-Jay
Subscriber

Anybody have a very easy way to explain this?

My 7 year old pointed out that a Bugatti Veyron & Abrahams M1A1 have very similar power (according to his Top Trumps). I then started to try to explain that the Bugatti engine is designed for bhp & torque is largely a by product while the M1A1’s engine is the other way round.

However explaining twisting moments & the relationship between torque/power is not easy to explain to a child.

clubber
Member

very simply

torque is how hard you can push
power is a product of how hard you can push and how fast you can do it.

For engines, it’s complicated by having variable torque across the rev range – power will typically be quoted as the maximum

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

IanMunro
Member

A quick calculation would suggest that in bottom gear on an mtb I can generate the same torque as a BMW Z4.
Of course the difference is that it can do it at 2,750 rpm, and I can do it at about 2rpm ðŸ™‚

Nico
Member

Power is torque times speed (engine speed, i.e. rpm). So a motorbike can have lots of power by revving fast. It won’t have much torque. A diesel Land Rover might produce the same power but have lots more torque. The motorbike engine will tend to have a peaky power band so it only produces high power over a narrow rev range and needs lots of gear shifting to keep going. But the engine will be lighter. The Land Rover will have a flatter power band making it easier to drive over variable terrain without changing gear all the time. Most cars come somewhere in between but sporty Hondas will be nearer the motorbike end of the scale whereas a diesel will be at the grunty end of the scale.

Member

weight is far more important.

Subscriber

Over steer: you bounce off the inside wall
Under steer: you smash your tail lights on the outside wall
HP: how fast you hit the wall
Torque: how far you travel when you go through the wall

aracer
Subscriber

weight is far more important.

So my 20 tonne rock will go faster than a motorbike? ðŸ˜•

coffeeking
Member

Over steer: you bounce off the inside wall
Under steer: you smash your tail lights on the outside wall

Oversteer you smash your tail lights on the outside wall, understeer you drive square into the outside wall, I think you’ll find! And how fast you hit the wall might be linked to HP but how far you travel through the wall would only be down to momentum.

Member
TandemJeremy
Member

A few years ago one of the motorcycle magazines put one of their journo on a dyno on his mountain bike. The power and torque curves were really funny – Huge torque at zero revs tailing off as the revs rose – from memory about 100ftlb or more at 20rpm – but peak power of 1.5bhp at 70rpm or so

speaker2animals
Subscriber

I was told 2 good analagies but can only remember one.

Power can be thought of as how hard you can swing/hit with a hammer.

Torque is how often you can swing the hammer in a given time.

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