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      04-27-2012, 07:53 PM   #60
TheRealOrosie
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Quote:
Originally Posted by bradleyland View Post
Regarding torque vs horsepower, keep a couple of things in mind.

Torque is a measure of force. I can generate 240 lb ft of torque with a torque wrench. Imagine you attach a wrench to the drive line of a 5-series. I can generate 240 lb ft of torque, but what do you think my 0-60 time would be? I can answer that for you: I'll be dead before I get that car to 60 MPH!

So if you want to know how well an engine will perform in your car, you don't just care about torque. The correct question to ask is, how many revolutions per second can I produce at 240 lb ft of force?

Horsepower is the answer to that question. The formula for HP is

t(r)/5252

Where t is torque and r is RPM. So torque times RPM, divided by 5252.

So back to the original quandary. You're all staring at me asking, "Ok smart guy, if it's not the torque that explains why the N20 is faster, wtf is it?"

To say the N52 or N20 generates 240 HP at the crank is a pretty shallow insight, because that's peak HP. Care to venture a guess how long the engine spends at peak HP during an acceleration run? It's a really small fraction of the time.

More relevant is the question of HP curve over the RPM range. Turbo engines have a huge torque swell early in their RPM range. Compare the HP generated by the N20 at 2500 RPM vs the N52 at 2500 RPM and you'll begin to see why the N20 performs so well. The N20 accelerates the car faster, earlier because it's generating more force (torque!) earlier in the RPM range (horsepower!).

Very well said.

Last edited by TheRealOrosie; 04-27-2012 at 07:54 PM.. Reason: format
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