As this is a question that comes up fairly often, I thought I should post a link to this article that I stumbled upon, which offers a reasonable explanation of gross vs net horsepower. If anyone knows more about the subject, or can correct any inaccuracies, by all means add your voice!


Understanding Gross vs. Net Horsepower Ratings
(by Aaron Severson, from ateupwithmotor.com)

- Eric

 

Thanks for posting the link.

It's an interesting read!

Jaybird

 

good artical

Gives me a better idea what my 330 will run the 1/4 mile in my Delta. Assuming is still has "320" hp after all the stuff is on the engine, then a drive line loss of appox 20%, I'm looking at putting down 231 at the wheels.

My 350 by the same calculations, was only putting down 184 HP

 

But conversely, what would a 2012 ZR1 vette be rated for back in 1970?

 

The same as is now. They have quietly reverted to gross HP ratings to bring the numbers back up it seems. I have been watching the powerblock shows and they chassis dyno a few cars and talk about the HP ratings and how they should see less due to drive line losses.

 

Whenever someone asks me how many HP my 71 350 4bbl has, I still just say "Not as many as you'd think, but still plenty" - I've long since given up trying to find out what it has and how it compares to newer cars. :P It's a jungle. But, I figure that it'll increase with high comp pistons.

 

Remember, rear wheel HP is not the same as engine HP, whether Net or Gross.

- Eric