[enkeivette]

Originally Posted by Vettezuki

Oh I misunderstood his test. I thought he had the engine fully dressed on the engine dyno and was measuring a 23% loss through the driveline alone basically. Let's say a more expected driveline loss is around 17% +- 1~%. That means there's something like an additional 5% from the accessories and exhaust. That's totally believable.

Yeah, you did the same thing I did. My first response to him was, 23%? Don't believe it.

[BADDASSC6]

Well This does seem accurate, but it's all int he definition of drivetrain losses. Most people call drivetrain losses as power that the motor is actually making that is lost in the inefficiency of the rest of the drive train. Here we are talking about a motor that was dynoed on two different dynos with different exhaust and other minor differences. If I dyno my car with open long tube headers then drop it in a car with stock manifolds. The chassis dyno will also show a +20% loss. Even greater with true 180 degree headers.

[jedhead]

Originally Posted by 94cobra69ss396

Yes but you have to remember that those flywheel numbers are SAE net numbers. That means the engine was tested with all belt-driven accessories, air cleaner, emission controls and a complete exhaust. Whereas the 496 for example was tested with open headers and an electric water pump only.

So the 496 flywheel horsepower numbers is more inline with the gross hp numbers of old then? That would explain the larger hp loss to the wheels.
BTW, the AC was running on my dyno run, I forgot to turn off the climate control or shut off the AC. I found out that in the STS-V the AC compressor is still engaged at WOT unlike most cars that I am used to that shuts off the compressor at WOT.

Bob

[94cobra69ss396]

Originally Posted by jedhead

So the 496 flywheel horsepower numbers is more inline with the gross hp numbers of old then? That would explain the larger hp loss to the wheels.
BTW, the AC was running on my dyno run, I forgot to turn off the climate control or shut off the AC. I found out that in the STS-V the AC compressor is still engaged at WOT unlike most cars that I am used to that shuts off the compressor at WOT.

Bob

Exactly, it is just like the old SAE gross numbers.

I'm surprised that your compressor didn't shut off at WOT. I thought that they did this to one help power output but two to help with fuel mileage.

[jedhead]

I was suprised too that the compressor doesn't shut off at WOT. Who knows, I might have been able to squeeze out a couple more hp with the compressor off. Next time, I'll remember.

Bob