So this torque vs p...
 

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[Closed] So this torque vs power thing?

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You have an engine running at a fixed rpm, connected through a gearbox to the road wheels. In low gear, you have highEr torque at the wheels, but low speed. In a higher gear, you have lower torque but higher speed at the wheels?

Is the ability of the engine to drive both these gears at a given rpm, the power output (PS or BHP)?

And presumably you could measure the torque of the drive shaft at different rpms to give the torque curve?


 
Posted : 26/11/2009 2:16 pm
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Torque multiplied by rpm is a measure of power, but not the power in useful units like BHP


 
Posted : 26/11/2009 2:23 pm
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What ampthill said: Power = Torque x Revs, in suitable units.

In low gear, you have highEr torque at the wheels, but low speed. In a higher gear, you have lower torque but higher speed at the wheels?

Yes.

you could measure the torque of the drive shaft at different rpms to give the torque curve?

Yes.


 
Posted : 26/11/2009 2:35 pm
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Torque and power are inextricably linked and the gearbox used will be designed to to make best use of the engine in question. Is this actually a question about petrol vs D driving? I think what's more important is the shape of the torque curve. Many engines can have similar peak values but they are only at certain revs, what you want is an engine with a very flat torque curve, providing instantaneous acceleration at all revs, ones that "ramp up" from low values tend to feel rather flat until you scream them to their sweet spot.


 
Posted : 26/11/2009 4:11 pm
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Power sells cars.

Torque wins races.

Can't remember who said that, someone famous.


 
Posted : 26/11/2009 10:39 pm
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Torque and power curves are what you should be looking at. I think. Admittedly you did state at the same engine rpm. The whiskey has just hit home at the same time I'm talking on a subject I only have a basic understanding of. I'll clock off on this one.


 
Posted : 26/11/2009 10:47 pm
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Torque is the measure of a engine's ability to do work. Hence why diesels have such good torque curves, they're able to put the bulk of the engine's power to use at relatively low revs.


 
Posted : 26/11/2009 11:21 pm
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Torque multiplied by rpm is a measure of power, but not the power in useful units like BHP

Newtons * Metres * radians/sec = Watts
746W = 1 BHP


 
Posted : 26/11/2009 11:41 pm
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this sums it up nicely I always think.

Understeer: when you hit the wall with the front of the car.
Oversteer: when you hit the wall with the back of the car.
Horsepower: how fast you hit the wall.
Torque: how far you take the wall with you.


 
Posted : 27/11/2009 7:48 am
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Quite a good explanation of P vs T: [url] http://www.seatcupra.net/index.php?option=com_content&task=view&id=56&Itemid=6 [/url]


 
Posted : 27/11/2009 8:59 am