How does RPM affect horsepower?

vetteeatr · 01-27-2002, 05:35 PM

I was just wondering how RPM relates to horsepower output. ALl Race enigne have crazy Rev potential so it obviously matters...

I mean I dont knwo if maybe i shoudl go to liek victor heads and intake and rev at 7,000 or is that too much?

Does it really matter compared to 6500?

All info would be appreciated. Thanks Guys

richd · 01-27-2002, 08:42 PM

Horsepower is the rate that the torque is being applied. Think of it this way:

Each cylinder produces a certain amount of force during the power stroke, let's call it X. For simplicity we'll assume that force is equal for any rpm. In an 8 cylinder engine there are 4 power strokes per revolution.

So at 1000 rpm the force being applied to the crank = X * 4 * 1000 = X * 4000 units of force per minute.

Move up to 5000 rpm and we see that the rate force is being applied to the crank = X * 4 * 5000 = X * 20000 units of force per minute.

The actual equation to relate torque to horsepower at a given rpm is

hp = torque * RPM / 5252

Not a very technical explanation, but I hope it helps.

Rich D.

50redvert · 01-27-2002, 09:32 PM

this is a cool page that tells about it

http://www.howstuffworks.com/horsepower.htm

01-27-2002, 05:35 PM	#1
vetteeatr Registered Member Join Date: Apr 2001 Location: Olney, Illinois, USA Posts: 212	How does RPM affect horsepower? I was just wondering how RPM relates to horsepower output. ALl Race enigne have crazy Rev potential so it obviously matters... I mean I dont knwo if maybe i shoudl go to liek victor heads and intake and rev at 7,000 or is that too much? Does it really matter compared to 6500? All info would be appreciated. Thanks Guys

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01-27-2002, 08:42 PM	#2
richd Registered Member Join Date: Jul 2001 Location: Edison, NJ, USA Posts: 125	Horsepower is the rate that the torque is being applied. Think of it this way: Each cylinder produces a certain amount of force during the power stroke, let's call it X. For simplicity we'll assume that force is equal for any rpm. In an 8 cylinder engine there are 4 power strokes per revolution. So at 1000 rpm the force being applied to the crank = X * 4 * 1000 = X * 4000 units of force per minute. Move up to 5000 rpm and we see that the rate force is being applied to the crank = X * 4 * 5000 = X * 20000 units of force per minute. The actual equation to relate torque to horsepower at a given rpm is hp = torque * RPM / 5252 Not a very technical explanation, but I hope it helps. Rich D.

01-27-2002, 09:32 PM	#3
50redvert Registered Member Join Date: Dec 2001 Posts: 32	this is a cool page that tells about it http://www.howstuffworks.com/horsepower.htm