[proracer4455]

Getting ready to put a supercharger on my car. So we did a Pre conversion dyno run which produced 454 RWHP on a completely stock motor. I was wondering if this is a normal number considering the factory HP representation. We did 3 pulls to make sure there was no fall off.

 

[jklotz10]

I'd say that's a good starting number. It's been said that the factory propaganda under-rated the HP on these engines. Keep in mind different dynos give you different numbers.
A rule of thumb is 15% drivetrain loss so 470 HP minus 15% would be about 400 HP at the rear wheels. That being said 454 RWHP aint too shabby at all. A different dyno may have come in lower but who cares.
The proof is using the same dyno and as close to the same weather conditions as possible when you run it again after the supercharger install.
The only thing that matters - how many ponies did you gain with the mod?

 

[proracer4455]

HP

I thought the numbers where a little high. My tuner Walsh Motorsports in Wixom MI. does a lot of these cars and th emost he has seen on a stock car with exhaust was 438RWHP.
Mechanicals taking place this week, Will post numbers and dyno sheet when completed......

 

[70barcuda]

I think you have an optimistic dyno, some dynos are known to give low HP readings while other brands tend to lean to the high side. About the only thing you are going to learn is what you HP gain is after you super charge and that does have some value. I have seen dyno number from the 392 run from a high 300's to the mid 400's at the rear wheel. I think the brand dyno probably has more to do with that, than that the cars actually vary that much from the factory.