Is there a conversion between Gross HP and SAE HP

[RU482]

I was reading an article about an older (60's era) car and they made a point to mention that the horsepower rating was gross horsepower. Is there any easy conversion to todays (american) method of measuring horsepower of a vehicle? If so, why don't the articles just do the math for us

 

[vi edit]

I beleive that it really depends upon just how much is lost in the drivetrain and especially in the auto transmission.

I've heard that at the wheels estimates are anywhere from 10%-15% of the "true" HP.

I think that's what you are looking for

 

[RU482]

could be, I didn't think of that aspect. good point

 

[Pacfanweb]

Yes, like vi edit said, in the 60's, HP was measured at the flywheel, whereas now it's measured at the rear wheels. I've always heard 20% used as an average loss from flywheel to the ground.

 

[Redneck]

The difference between gross and SAE (net) HP, is that gross hp tests were run without accesories (A/C, power steering, etc.) and now they are run with all the accesories, which gives a better idea of the performance you will see on the road. Car makers stll use flywheel numbers because lets face it, bigger numbers look better.