Proof SAE Correcton Factor is BS for Turbo Diesels??

[Dockboy]

Most of you know my opinion of SAE Correction Factors when it comes to Turbo diesels. Especially when it comes to running nitrous.

Well, I had the oppurtunity to put my theory to the test in the past couple weeks. Two weeks ago I dynoed on David Dunbars Dynojet 248C in Tenn. The CF that day was 1.04. Dynoed 574 #2 only and 758 w/nitrous corrected. Uncorrected actual power put to the dyno was 551 #2 only and 727 w/nitrous.

This weekend I dynoed on Kauffmans Dynojet 248C. The CF was 1.00, or in other words, nothing. Take a guess what I put down in the same settings?? 552 #2 only and 729 w/nitrous!!!!

So you tell me..........did I mysteriously loose 22 hp on #2 and 30 hp on nitrous as the corrected numbers would indicate?? Or is it that the CF designed for naturally asspirated gas motors is not valid for forced induction diesels given the fact I put the nearly exact same hp to the ground at both locations despite the difference in alltitude and correction factor????

Lets hear what you think!!

 

[joefarmer]

With 2 power adders, CF is null and void. My 99 w/twins did 648.6hp in Columbus, Ohio. I sold it and the new owner dyno'd it at a diesel event in SoCal at 648.1.

I think it still applies to some extent on a single 'charger because I can tell a big difference on turbine stall RPM on my single without nitrous. On a 55F night, I can spool to 1750rpm. On a 90F night, I can only get 1450rpm before I stall against the convertor.

brandon.

 

[weweld]

I read that if you run a turbo the correction factor is cut in half and if you add nitrous you cut it in half again so that makes it pretty much GONE. I think we can toss it out but that's just my $.02 worth , which ain't much.

 

[McRat]

Correction factors are used to help tuners who are doing on-going projects. They are not perfect even for NA gas engines.

This is why you should always be able to "baseline" your first pull to get a number to calculate from.

Yes, the NHRA uses 1/2 the DA correction for super/turbocharged engines. And if you "bring your own air" in a bottle, and tune for it, altitude has almost no effect.

But more importantly, dynos are tuning tools that are mistaken for infommercials. They can only be used to compare two things to each other the same day, the absolute number is not really useful for comparing a truck in Maine to a truck in Washington.