Rated engine power
How do manufacturers, presently, determine how to rate their engine's crankshaft horsepower? Is the cooling fan engaged and drawing air? Alternator charging? Power steering pump and A/C installed and ...
Forum Discussion
All manufactures rate horsepower at the crankshaft when it advertised. It is full accessories and emissions.
Cars in the 50, 60, 70's were rated with no accessories. That is why if you were to test them today you see they are lower than was advertised and slower then what they should be for rated power.
On average when you do a dyno pull in a manual you expect a 10 to 15 percent loss through the drive train. In auto 15 to 20 percent loss. This is average and it varies case by case.
I will use my WS6 for an example. It was rated at 320 to crank by GM. It dynoed at 328 bone stock. Underrated by GM. You hear about that one on a lot of cars. It also depends on what kind of Dyno and conditions that day.
The rated HP from the manufacture is done in controlled conditions and has to be repeatable.
Cars in the 50, 60, 70's were rated with no accessories. That is why if you were to test them today you see they are lower than was advertised and slower then what they should be for rated power.
On average when you do a dyno pull in a manual you expect a 10 to 15 percent loss through the drive train. In auto 15 to 20 percent loss. This is average and it varies case by case.
I will use my WS6 for an example. It was rated at 320 to crank by GM. It dynoed at 328 bone stock. Underrated by GM. You hear about that one on a lot of cars. It also depends on what kind of Dyno and conditions that day.
The rated HP from the manufacture is done in controlled conditions and has to be repeatable.
