Horsepower vs torque

[HoopDawg42]

Hp is a calculation of torque. Dynos don't measure Hp, they measure torque. hp=torque x rpm/5252. 5252 is the rpm at which the torque curve and the hp curve cross. All that BS said...torque's what gets you moving.

 

[3rd Rail]

Having studied some interesting work on the development of racing engines over the years, that's a bit simplistic, and not entirely true. Torque has some correlation to swept volume, hp to volumetric efficiency.

It really is pretty complex and depends on application. For another example;

hp rpm ft-lbf rpm
247 5000 313 1750-4000
330 7000 270 5200

In the same weight vehicle, from a standing start, with an auto transmission, which would hit 60 first ?

Its a trick question. Converter stall and final gear ratios are undefined.

 

[3rd Rail]

Hp is a calculation of torque. Dynos don't measure Hp, they measure torque. hp=torque x rpm/5252. 5252 is the rpm at which the torque curve and the hp curve cross. All that BS said...torque's what gets you moving.

And rpm has time component. Much like velocity and mph.

My assertions are simple and intentionally brief. There's plenty of internet on the topic for anyone that wants to take a deep dive.

Torque is great. HP is torque represented with time.

 

[Amplifize]

Hp is measured when an engine is running free, torque is measured when an engine is put under stress or hooked up to a drivetran

 

[Mister Heavyhand]

OK so Torque (in foot pounds) = HP*5250 / RPM. Curves cross at 5250 rpm

http://www.epi-eng.com/piston_engine_technology/power_and_torque.htm

 

[Lockout]

My Duramax put down
680hp 1250 torque to wheels

 

[spencer60]

Torque is what makes you go. Horsepower is what makes you go fast. There's no such thing as too much of either one... or both.

(except in snow... don't ask).

 

[StuP]

OK so Torque (in foot pounds) = HP*5250 / RPM. Curves cross at 5250 rpm

http://www.epi-eng.com/piston_engine_technology/power_and_torque.htm

I really don't think that's an absolute correlation. And certainly HP / Torque curves don't coincide at the same rpm regardless of the engine being tested.

 

[Amplifize]

You get more torque form a heavy flywheel spinning, it takes HP to make said flywheel spin, the more HP you have, the faster said flywheel will spin.....

 

[Amplifize]

Look at a diesel engine, not a lot of rpms, but spins a lot greater mass, crank, flywheel, etc. The torque comes from the mass of the rotating assembly