Proof that SAE correction for turbo diesels is more wrong then right??????

c-hawk

c-hawk

Liberals Suck...
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Jun 26, 2006
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Both charts show the same 4 pulls, all made on the exact same dyno, with the exact same truck with the exact same setup. The runs labeled Chris Hoofnagle 001 and Chris Hoofnagle 002 were done in NC (approx 650' elevation, 79*, 75% humidity), and the runs labeled Chris H 001 and Chris H 002 were done in MD (approx 50' elevation, 60*, 35% humidity). Both graphs show the same exact four pulls, the two from NC and the two from MD.

The first graph shows the runs corrected.
corrected.JPG

The second graph shows the same runs uncorrected.
uncorrected.JPG

The corrected runs show a spread of 21+hp and 50+ ft lbs tq difference from the two locations. The uncorrected runs were all within 3hp and 9 ft lbs tq, regardless of location.

I still believe hot, muggy air takes away power and makes it harder to light the charger, etc., but the correction factors are way off on our trucks... more wrong then right i think.

Chris
 
c-hawk said:
Both charts show the same 4 pulls, all made on the exact same dyno, with the exact same truck with the exact same setup. The runs labeled Chris Hoofnagle 001 and Chris Hoofnagle 002 were done in NC (approx 650' elevation, 79*, 75% humidity), and the runs labeled Chris H 001 and Chris H 002 were done in MD (approx 50' elevation, 60*, 35% humidity). Both graphs show the same exact four pulls, the two from NC and the two from MD.

The first graph shows the runs corrected.
View attachment 3195

The second graph shows the same runs uncorrected.
View attachment 3196

The corrected runs show a spread of 21+hp and 50+ ft lbs tq difference from the two locations. The uncorrected runs were all within 3hp and 9 ft lbs tq, regardless of location.

I still believe hot, muggy air takes away power and makes it harder to light the charger, etc., but the correction factors are way off on our trucks... more wrong then right i think.

Chris
Click to expand...

She's pretty darn consistant
 
The SAE correction factor only applies in the west LOL
 
Please one of you bring your trucks up here for Truckfest and see what happens... please. I got into this discussion with Don and few others awhile back on NW. From my perspective I won. I'd love to do it again lol.
 
Yup. The reason our Blue Truck runs 13.6 @ 98 at 4600' DA and 13.1 @ 103 at 1200' DA with the same tuning is because all high altitude tracks are aimed uphill. I believe it's a federal law or something.
 
PS - if you use about 50% of SAE correction factor, you will be in the ballpark for most turbo engines.
 
Only Chebies and Ferds require something that outlandish lol!

So 3400ft change in elevation caused a 3.8% slower ET. Come up and dyno at Denver at 5800ft and flatlanders will scream bloody murder when you use a 10% CF. People will argue that track times don't correlate exactly with dyno runs due to the fact that you are pushing less air traveling down the track at higher elevations. On the dyno and the factor is removed...
 
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True, but you can compare correction factors which is what we are doing ;)
 
None of the "available" correction factors work on turbo engines, since it varies based on the map of the charger.

Turbos function based on pressure ratio, so the thinner the air, the less boost/oxygen, but since they are capable cramming air in even when the efficiency is lower, they don't lose ALL of the power, just some. Anyone who has towed in the mountains has seen it.

You can't go % with ET's since it's acceleration. Our white truck ran 12.25 at Palmdale on Wed, then on Friday it ran 11.77 at Famoso with no other changes. Physical alt difference was about 2500', don't remember DA though.

Whenever we want to set a new best, we get it dialed in locally at altitude, then head down to the flatlands to drop ET.
 
You're confusing instantaneous acceleration which is exponential with average acceleration. Newton's second law states that Force = Mass * Acceleration. Flipping that around A = F/M. With M remaining constant, F is then linearly related to A and my previous statement stands lol
 
I think your flipping is off. :D

Mass is fixed, time is a function of the acceleration which is a square, hence non-linear. To cut ET in half usually takes over 4 times the power at the same HP.

Example, our truck with 245rwhp goes 16.40. Double it, 13.10. Triple it, 11.15, at the same track. Lots of other variables going on, but it's nowhere near linear.

So the 4% difference in an ET takes more than 4% power increase.
 
My best guess is that at 7500lb, and in the 13's, each .1 second drop takes 10rwhp. So to lose a 1/2 second at those levels, means you've lost 50rwhp.

Maybe. Who the hell knows? :D
 
:pop:

I tried to word my original post carefully.

I have no doubt that heat, humidity, altitude, etc. have an impact on the power these turbo diesels make.

All i'm saying (atleast what i think i'm saying), is as far as dyno numbers go, uncorrected numbers are probably closer to reality then SAE corrected numbers. The SAE correction adds, or takes away too much on these trucks.
 
c-hawk said:
:pop:

I tried to word my original post carefully.

I have no doubt that heat, humidity, altitude, etc. have an impact on the power these turbo diesels make.

All i'm saying (atleast what i think i'm saying), is as far as dyno numbers go, uncorrected numbers are probably closer to reality then SAE corrected numbers. The SAE correction adds, or takes away too much on these trucks.
Click to expand...

Bingo Chris!!

I proved this also last year!!

Dynoed at Smokin in the Smokies on Dunbars dyno. There was a 4% CF that day.

Corrected numbers were:

758.8dyno.jpg



Uncorrected numbers were:

727.6dyno.jpg



2 weeks later, I dynoed at Kauffmans with no CF. Guess what?.......................................

I did 551 on fuel and 729 on nitrous:poke:
 
Greg...Your data is no longer relevant since you lost the death match race....:hehe:
 
McRat said:
I think your flipping is off. :D

Mass is fixed, time is a function of the acceleration which is a square, hence non-linear. To cut ET in half usually takes over 4 times the power at the same HP.

Example, our truck with 245rwhp goes 16.40. Double it, 13.10. Triple it, 11.15, at the same track. Lots of other variables going on, but it's nowhere near linear.

So the 4% difference in an ET takes more than 4% power increase.
Click to expand...
Not exactly. While it's not linear, it's also not a square either. I'll stipulate that it's been several since I cracked a physics textbook if you'll do the same lmao.

perf1.gif
 
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