tomgillotti

Seems to make sense... So does anyone know how a car company comes up with initial crank hp and tq ratings?

Stamina

Engine dyno

tomgillotti

Hmm... learn something new everyday. Is that something I can have done when I get my car dyno'd for the wheel hp and tq??

Stamina

No, most tuners won't have one. Usually only manufacturers and maybe engine builders would have one.

The dyno people usually use is called a chassis dyno. It measures the power that you're getting to the ground, and is more "real-life" and what people are wanting to know anyway.

That is why the advertised HP/torque of an SS/TC is 260/260 for instance, but when stock on a dyno they're getting less than that. That's because the numbers the manufacturer gives you are always engine numbers, because drivetrain efficiency losses vary and would always be lower than the engine rating (a lower number wouldn't excite the customer as much either).

So if you dynoed your car and it showed it put out 260HP and you ran another SS/TC that was rated from the factory at 260HP, you've actually got more power than they do.

ford

I believe the RPD to be inaccurate simply from the butt dyno. It showed me pushing 266tq on the way home but it was barely spinning tires. I put the intake on the car and it ripped 1st and a lil into 2nd and it shows less torque like 237max. Mind you i wasnt watching the HP on the way home so i didnt compare that.

All in all i love the RPD though

VolkSS

I was told by Vince that the HP numbers are a calculation done using the MAFS. So, if you have upgraded your intake, those numbers will be skewed. In my case, with the tune and stock intake, the RPD was reading above the max of 325 HP. With the intake installed, it's reading about 310 HP. However, my butt-dyno tells a different story.

cranemaster

If I had to guess it's probably software limited to stock and gms1. And it could be moderately accurate with your car in stock tune trims...

I'm gonna take a look at mine today and see whats up. I'd expect in the ballpark of 280-300 tq.. Il see what it reads.