Trick Turbo Drag Times!!!!
05-10-2007, 11:12 PM
#22
The boost number on the gauge stays the same since it references boost to static air pressure, but kPa that the MAP sees will increase about 15-20 kPa at sea level, which is about 2-3lbs of boost. I know I have to make almost 10 psi I up here where I live (WY 5000ft) compared to 7psi when I'm down in AZ. Its a BIG difference in power. His 10 psi is like most people's 7-8.
Last edited by kbracing96; 05-10-2007 at 11:50 PM.
05-10-2007, 11:53 PM
#24
Originally Posted by Spoolin
You should come to the Sac June 22nd gtg and run your beast there!! Then you'll really know what that thing is made of AND...I'll get to see it!! Haha.
Q: there's no debate that altitude effects HP especially on N/A motors but how big of an impact on turbo applications? S/C usually see a small drop in PSI but turbo's still see the same amount of PSI, turbo works more to make it but eventually the wg open's up at the set PSI anyways. So with 10 psi at sea level and 10 psi at 5,800 ft, your only seeing a small drop no?
Q: there's no debate that altitude effects HP especially on N/A motors but how big of an impact on turbo applications? S/C usually see a small drop in PSI but turbo's still see the same amount of PSI, turbo works more to make it but eventually the wg open's up at the set PSI anyways. So with 10 psi at sea level and 10 psi at 5,800 ft, your only seeing a small drop no?
Take that same truck to Houston and it would fly.
05-11-2007, 12:34 AM
#25
Ok this is clearing things up for me. I knew altitude robbed HP in all kinds of engines but wasn't sure how it did so with turbo's. 10psi at 5,800 ft is NOT the same as 10psi at sea level due to less O2 in that 10 psi charge. 
Thanks for the clear up!
Thanks for the clear up!
05-11-2007, 08:54 AM
#26
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I think that summed it up. I drove my sc truck to Texas a while back and it felt like it had an extra 50 shot of nitrous on it.
05-11-2007, 09:30 AM
#27
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Don't forget that in order to produce X amount of psi at a higher elevation vs. sea level, you're now in a different part of the compressor map, thus affecting the efficiency of the compressor which is directly seen in your IAT's.
Elevation plays a role, but so does weather. We're at 3000ft of actual elevation here, but our DA's due to hot weather usually hover around 6000ft. Low barometric pressure, high temperatures and humidity all attack power output. DA is the best measure, not actual elevation. You can be at 5500ft, but if it's 65*F and the air is dry, it might not be as bad as being at 2500ft when its 90*F and 80%RH.
Elevation plays a role, but so does weather. We're at 3000ft of actual elevation here, but our DA's due to hot weather usually hover around 6000ft. Low barometric pressure, high temperatures and humidity all attack power output. DA is the best measure, not actual elevation. You can be at 5500ft, but if it's 65*F and the air is dry, it might not be as bad as being at 2500ft when its 90*F and 80%RH.
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