Effects of altitude on our CTD

[azcummins]

Just got back from RMTDR Dyno Days and my 98. 5 3500 with EZ and DDIIs pulled 304 hp and 840 ft/lbs torque.



That dyno run was done @ 6000 ft so I was wondering how my truck might have done @ sea level.

 

[Joseph Donnelly]

Most dynos use the SAE correction, which is designed for normally aspirated engines. When altitude gets high, the correcting factor is too big for us. For a rough estimate, look at the uncorrected and corrected numbers and go maybe a fourth to halfway in between, depending on altitude. the higher the altitude, the more exaggerated the correction vs. what it should be.

 

[andrewkoperdak]

I like your power numbers. I just put in a set of Stage 3 injectors (100+hp). Soon as I get more free money I will dyno.

IMO: I was lead to believe that altitude was a non-issue on our turbo diesel. The turbo makes the positive pressure which negates any altitude. ON regularly aspirated vehicles, they don't get this benefit. So the higher they go the less pressure they get. 22 psi at 8000 feet is = to 22 psi at mean sea level. Maybe someone here can teach me something. It won't be the first time.

Andy

 

[C Schomer]

I'm not positive, but I think those are uncorrected numbers. I dynoed mine there a couple months ago - best #s were 292/812 and they made a comment that anything close to 300hp at that alt. was darn good. Last fall a guy with a 24v and comp box did 301hp. I think his was the best of the moderate trucks. Mark Chappell said a TD only looses 1. 2%/1000' alt but I think that is low. 300hp would still be about 270hp on top of Loveland... I don't think so! Craig

 

[CCahill]

The big diff I've seen @ say 7000 feet is more of a driveability issue. Still seems like the same power... Just pipey... like a two stroke. . if ya know what I mean. . Also takes longer to spool, so way more black smoke... even with my sampler size HY. .



Colin

 

[R.ebel]

Altitdude & Turbo's

I live at 6000 ft. and thought I'd throw in my $0. 02 I haven't noticed much difference in power when I tow at sea level altitudes, but there is a big difference in boost and EGT's. The turbo on my truck is a PDR HX35-16 superturbo (poor mans HX40). At or near sea level my engine makes 4 more PSI of boost, because of this egt's climb a lot slower and I'm hard pressed to get the EGT temp up to 1250 deg. But towing the same load on a 90 deg. day at 6000 plus feet you really got to watch the EGT gauge to stay out of trouble