Now I would say that most people understand that horsepower is just a derivitive of torque, and that torque is the amount of rotational force...but that's not a very colorful description...

Can you guys throw out some of your best analogies (or link to old posts) to try and explain the relationship to those of us who can't visualize the difference?

Try to do some explainations in this format: horsepower is to torque as blank is to blank. (SAT style!)

I bet a few good analogies would make a world of difference in a lot of our understanding of tq/hp, thus alowing us to better grasp exactly how various enhancements increase engine performance.

 

horse power is not a derivative of torque. they are simply a linear relationship
hp = torque x rpm / 5252

 

Burke's got the equation right. Here's another explanation...

Torque is simply the twisting force. I can make 800 lbf*ft of torque with my bare hands. I just need a really long pipe on my wrench handle.

But I can't produce that twisting force at a speed of even 200 rpm. So HP is a way of saying (mathematically) that your engine can produce that twisting force AT A SPEED OF xxx rpm.

Another way to look at it? Think of pushing a car out of a snowdrift. You can push (with your hands) on the back bumper with a force of 100 pounds. But you can't give that same 100 pound push while running behind the car at 30 mph.

 

Horsepower can be looked at as the rate at which torque is applied, similar to what JimBlake was saying about pushing the car.

 

Those are exactly the kind of analogies I was looking for...a lot of other things about torque/hp numbers are now falling into place...

Thanks so much for the posts...I've been living/breathing HT for the last three months and I cannot begin to describe how much I've learned about vehicle performance. You all make HT a truly invaluable resource.

<-- Stoked