rule of thumb ET vs. altitude?

Ron E · Post by **Ron E** » Sun May 18, 2008 12:56 pm

Is there any general formula that gets close? I tried using NHRA's track correction factor, but it's a little optimistic.
I'm trying to get an idea of what a NA 8.87 run @ 2584 ft. DA would roughly equal at sea level. Any ideas? Thanks in advance.

MileHighMan · Post by **MileHighMan** » Sun May 18, 2008 8:30 pm

I've always heard, every thousand feet you go up cost you about a tenth. Seems pretty close. I think you got a 8.50 car there. Good Luck. Dan.

Post by **ClassKing** » Mon May 19, 2008 12:57 am

NHRA's factors are very very close. When I went 9.91 at Vegas the factor estimated high 9.60's in fair air at Pomona. Two months later I went 9.67 at Pomona. Your chassis has to work very well.

Ron E · Post by **Ron E** » Mon May 19, 2008 7:03 am

I appreciate the input.....and I hope it works out that way.

rustbucket79 · Post by **rustbucket79** » Tue May 20, 2008 2:24 am

I took my low 11 sec car from my local track of 2300' actual altitude to a sea level track of 50' altitude, DA difference was roughly 5000 locally to 900 at the sea level track, the car dropped just over 2 tenths in the quarter.

On a high 8 second car a D/A change of 2800', I'd be thinking a tenth, maybe one and a half.

David Redszus · Post by **David Redszus** » Wed May 21, 2008 11:04 am

An engine that is properly tuned at an elevation of 2584 ft
when run at sea level will require 11.89% more fuel and will produce 14.44% more power (at the same inlet temperature).

How this increase in power will translate to track time is another matter since the aero drag due to increased air density must also be considered.