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Darth Vapor SRT 06-10-2013 08:59 PM

What's the deal with the HP claims?
Sooo Mopar says 2012 puts out 470 hp and 465 tq. Yes I realize thats not to the wheels. But I've been reading that the actual HP is closer to 400?

ECSZ06 06-10-2013 09:57 PM

Re: What's the deal with the HP claims?
Where did you read that. Maybe they ment to the wheels where its around 380.

K_SRT8 06-12-2013 04:06 AM

Re: What's the deal with the HP claims?
if the engine makes 470 hp then at wheels you will get 400 hp because of the 15% drivetrain lose.

forza 06-12-2013 04:17 AM

Re: What's the deal with the HP claims?
You got to remember too that the engines when they are rated on HP are done in a controlled environment on a test stand. Not in the vehicle. I was also reading that if you have an AWD dyno done to take the wheel HP and divide that by .82 to give you the crank HP. So if you had a 380 WHP then you would have about 463 hp at the crank.

DanMartin 06-26-2013 11:44 PM

Re: What's the deal with the HP claims?
My bone stock 2006 GTO rated at 400hp put down 342 at the rear wheels when I first bought it. Almost exactly 15% loss.

AWD is typically more parasitic loss than RWD/FWD (you're turning a lot more stuff). 18-20% is common. Assuming 20% loss, you should see about 370 at the wheels on a stock SRT.

Since 2005 many auto makers have adhered to the SAE J1349 standard, where the engine is tested with emissions and exhaust in-place (SAE NET) and the test is certified by a third party observer. Automakers can state different HP ratings, but they cannot state "SAE HP" as the look for those three letters. A short search did not yield any results officially from Chrysler with SAE NET HP for the 6.4 (I hope someone can find something that maybe I missed).

Regardless...if people are seeing 380 at the wheels on a dyno, there's likely 470 or so at the crank with the motor in full production trim.

jim383 06-27-2013 05:35 AM

Re: What's the deal with the HP claims?
My 07 srt8 gc jeep was rated at 420 hp 420 tq and bone stock on a AW DYNOET put out 341 hp and 352 tq now that 18.625% hp drop and 16.125% tq drop. Now with the 2012 if i ran on same dyno and the hp & TQ lose would be the same % AS MY 07 the hp would be 382 and tq be 390.

A.V.GCSRT8 06-27-2013 08:23 AM

Re: What's the deal with the HP claims?
With the calculations you use Jim from our track times I think it backs up those numbers as well

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