Originally Posted by THE EVIL TW1N
Your in your own world man. It's already been stated that the engines (3v 4.6's) are slightly underrated, probably by about 5 to 10 hp using the NORMAL driveline losses of 12% when on a dynojet.
Awesome... only problem is that has nothing to do with the actual discussion.
Here, let's rescope - since it seems that the actual discussion is getting skewed with data points that don't have relevance.
Subjective: "V6 camaro dyno numbers are low"
Scoping: Initial review - They're spot on for the AF mix, tire size, temp, dyno type and miles on chassis @ 18% (automatic) loss. I would expect these numbers to be combined with other future pulls from other cars, in order to get a collection metrics from which conclusions can be drawn.
Contention: Car X only has 8% driveline loss... that is the "norm"
Resolution: We've already shown that this is not the case with any production vehicle, 8% is a totally fictitious number based on the flawed logic that BHP calculations from the manufacturer are a constant.
Rwhp numbers are used to compare with the horsepower claims of the manufacture (assuming we're talking about baseline pulls in a stock vehicle) in addition to calculating gains made by outside influences. This number can either be higher, or lower, than the manufacturer claims. In the examples posted, it's clear that the manufacture under-rated the power output of their engine in that specific chassis. It does NOT however illustrate, in any way shape or form, that the it was the driveline loss
percentage that changes, rather than the initial evaluation of the bhp rating.
If we need to, we can illustrate the inverse of this rwhp calculation.... that is, listing engine HP calculation based on torque output delivered at the wheels. If car X put down 300rwhp, without making any assumptions about BHP... are you going to assume it:
-Has a "normal" loss of 8% - for a total of 324bhp
-Has a "normal" loss of ~15% for a total of 345bhp
Given the fact that there is *plenty* of historical data supporting average loss >8% and <22%, the larger number is going to be the most accurate rating based on the metrics given.
/Cliffs: We all bitch at each other, but yet the dyno numbers I posted haven't changed