Quote:
Originally Posted by NISSANSPDR
dynamometer: An electric or hydraulic machine used to measure the actual engine horsepower output and torque. An engine dynamometer measures horsepower at the crankshaft and a chassis dynamometer measures horsepower output at the wheels

Wrong. A dyno measures torque and torque only.
HP is acquired mathematically. Torque X RPM / 5252 = HP (Though that's just general, the equation doesn't work for EVERY vehicle, but works for most.)
Take my 2.8 for instence:
160lbs @ 3600
160 X 3600 / 5252 = 109.67hp @ 3600RPM
The dyno is doing this test all the way through so, every time torque increases or decreses it does this equation and eventually find peak HP. Which should be 130 @ 4800 for that motor.
"x" X 4800 / 5252 = 130
.91x = 130
130/.91 = 142
so it makes 142lbs @ 4800 RPM Now to verify that because my math skills are somewhat lacking...
142 X 4800 / 5252 = 130
129.77 = 130 (Correct, i rounded it off in the earlier equation)
So that's how you find out power at certain RPMs.