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im confused......i thought that on a dyno chart the HP and torque are supposed to cross at 5252rpm, correct? well, what if the car doesnt redline that high, for say, a disel that redlines at perhaps 3k rpm.......what happens when you dyno one of those trucks or something

 
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calibrate it so it dynos a disel?

 
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Then the curves do not cross. There are no exceptions to that equation.

 
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That doesn't make any sense..... wouldn't different engines have different HP and torque curves!?

 
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What doesn't make sense?
HP is derived from torque.

And like Boilermaker1 said "There are no exceptions to that equation."

 
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OK, I see where you're coming from... Just at that given point (5252 RPM), the curves MUST cross. But it can be at any value along the scale, and the curves can do what ever they want before or after that point.
Different engines DO have different HP and Torque curves. Go to Injen.com and look at all the dyno graphs. They're all different. If they were all the same, then there'd be no need to dyno your car since you'd know what it looked like.

The Equation reads: Horsepower = Torque*RPM/5252
Power is in Horsepower and torque must be in lb-ft.

 
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Sigh... i suppose this is eaiser then personally schooling people...

http://www.stanford.edu/~voloshin/lhowwhy.html

http://wahiduddin.net/calc/cf.htm

http://www.howstuffworks.com/horsepower2.htm

-j