RWHP to engine HP ?

[JLEONARD]

Looking for some general wisdom here... . what is the relationship from rear wheel hp numbers from a dyno run to engine hp?

My truck is a 5 speed with 3. 54 axle ratio.

I have heard 20% loss thru the drivetrain (on a manual) in the past. Is this true?

The reason for the Q is I am converting a 1st gen engine for a boat and I want to be able to tune it to a certain hp range and was hoping to be able to correlate my results with the task at hand.

Thanks in advance.

 

[Wiredawg]

I'm just throwing a dart at it... I've heard 15% to 20% for autos and 8% to 10% on manuals. I believe the loss is a combo of load vs no-load and drive train (transmission) slippage. Now, maybe one of the dyno expert may chime in and offer a better and more accurate explanation.



Wiredawg

 

[GIT-R-DONE]

FWIW and its just my opinion. I had an 02 H. O Rated stock @ 245 HP and dynoed 234 hp. I would have to look up the dyno sheets but. . . if there was a 20 percent loss of the drivetrain, that would have meant my STOCK H. O. from the factory ws pushing 280, and I doubt that motor from the factory was @ 280 engine HP.



Sorry , I dont have an answer, just throwing out som einfo that makes the 10-20% loss seam a little high.

 

[WMonroe]

My 07 has about a 13% drivetrain loss if the factory engine rating is correct.



Factory rating 325 hp



Stock dyno 282 hp



Will