Definition of Engine Hosepower & Torque

[Cruiser_Air]

When we look at the manufacture specification sheet, one of the major parameter for evaluating the vehicle is the engine horse power & torque.
But who knows what is the definition of the engine horse power & torque.
Or exactly to say, where the engine horse power & torque measured? Measured on engine shaft? engine crank shaft? or wheel axle?
any expert can help me to understand this issue?
Thanks a lot.

 

[03_4x4Runner]

Torque vs. Horsepower - Engine Power Delivery Explained - Hot Rod Magazine

also

http://www.carcraft.com/techarticles/horsepower_vs_torque/index.html

 

[Cruiser_Air]

Thank you very much for you information.
One more question. I heard that US standard measure the engine horsepower & torque on the wheel axle, but Japanese standard measure on the engine shaft. is that true?
If it is true, then that is a big different.
Anyone can help me to get the answer?
Thanks a lot.

 

[03_4x4Runner]

Thank you very much for you information.
One more question. I heard that US standard measure the engine horsepower & torque on the wheel axle, but Japanese standard measure on the engine shaft. is that true?
If it is true, then that is a big different.
Anyone can help me to get the answer?
Thanks a lot.

I do not think that is true. I am almost sure the use the same SAE standards.

 

[Renegad44]

Yep, torque wins races, horsepower gets you there faster.

 

[Cruiser_Air]

Power = Rotation_Speed X Torque
at low speed, can get higher torque, at higher speed, torque drops. Enginer horsepower is the basic engine capability for generating power from burning fuel.
one of my co-worker explained to me, that US standard is to measure the wheel axle horsepower for engine horsepower, but Japanese standard is to measuer the engine shaft horsepower for engine horsepower. That's means a big different between them, from engine shaft to wheel axle, there are lots of power losses that does not apply to wheel axle horsepower. I have keep asking the dealler this questions, but no one can help me to get the answer.