Nicks Garage 383 build

RAMM said
At the risk of this thread becoming even more convoluted-Its not really the correction factors, everyone uses the old STP/SAEJ607 and not the newer SAEJ1349 which is how the OEM's rate their products. Dyno's are all over the place more than likely because of other factors like cell construction. Where does the engine receive its intake air from? How is the air circulated/exchanged? Is the air pushed in or pulled out? I know of a dyno facility that doesn't even have any air movement at all, so as the day goes on it just gets hotter and hotter and more contaminated. That definitely effects the numbers. @ UNOH they blow air into the room while my own system blows it out. What does the exhaust system look like? I'm below grade so my exhaust actually travels up and then out about 13' into 6 large mufflers. How restrictive is the system? Is there any weird adapters involved? And so on and so forth. Correction factors can't possibly account for all of that with 100% accuracy, but it actually does a pretty good job. FWIW I think Nick's dyno is spot on and maybe even on the "tight" side. J.Rob

I agree test proceedure and control over variables are very important.
I think correction factors are most useful when comparing data on the same dyno on different days. I also think correction factors are more accurate when they don't have to correct very much. Unless you are testing under conditions close to 60 degrees, 29.92 pressure and 0% moisture, why wouldn't you use a correction factor closer to the actual conditions you are testing at? I can think of a few reasons and these are not without some merit.
1. Everybody else (my competitors) uses it.
2. That's how I have always done it.
3. I can't or don't know how to change it.
4. I didn't know there was an alternative.
5. It gives me or my customer bigger numbers.

Just to name a few I'm sure there are other reasons.
Just so you don't think I am "correction factor Shaming". I have three correction factors loaded into my dyno program. I do all my testing with the CF that is closest to my conditions J1985. If it is a street or non competition type motor I will also offer (with a shortish explanation) the "higher" numbers with the J607 standard. I ask the customer which they would like me to print out for them. Guess which one they choose? If I were them I would probably pick the bigger numbers. It's human nature I think.