I've seen people adjust their 1/4 times for higher elevated areas to bring it down to sea level times? Is there a difference? I ran a 13.9, but was like 3400 feet above sea level. Is there a difference or no? Thanks a ton.
JOHN

 

well you can correct strictly for altitude, or for density altitude. DA takes into effect elevation, pressure, humidity, and temperature. Elevation just takes into effect just that.

There are numerous calculators on the web, ill let some others like their favorite, but i like the one at www.stangbangerz.com. Its the local mustang board, but it works. Go to tech tools, the ET sea level correction or whatever it is.

 

heres a direct link...

http://www.stangbangerz.com/modules....h&file=density

 

also http://smokemup.com/auto_math/nhra_c...on_factors.php

fbody.com

using fbody thats a 13.22 DId they anounce 3400 as the DA or the actual track altitude you looked up?

-brent

 

NHRA Altitude Correction Factors

 

Thanks! I'll try it out.

 

It was on a road trip in New Mexico. The track was like ~3370 from what I remember them saying. It was north of Lubbock, which is 3200. It was about 96* and a ton hotter on the track. The humidity was at ~60%. So, it is ~mid to low 13's, which I'm happy with. Thanks for the quick responses and great info!!
JOHN

 

Fred,
That smokemup site also has the official NHRA ones listed. Does the NHRA also have an official formula for DA correction?

 

that one is bogus. according to it, i should be running 9s corrected at 137 mph

 

Ive always had very good consistent reults with it, and they seem to be pretty good to real world. I can go out and run 14 flat at 1000 DA, corrected to lets say 13.5.


Go out on a 0 DA day, and i run that 13.5.

Try using standard pressure and just the track elevation and see what happens, or vice verse.

 

NHRA simply publishes tables of correction factors, and states which tracks they apply to. I don't think they allow correction at altitudes less than 1,600-feet. Note also that they have different tables for different classes. The Stock/Super Stock ones are the most applicable to an NA street car. I think the others may be more applicable to power adder cars/classes, where altitude has less impact.

You can derive the formula they used from the tables. I can post it here if you are interested. They actually use an altitude of about 230-ft as the baseline, not "0".

 

OK, if you know the DA or your actual altitude then you can use the NHRA tables to adjust for the weather conditions and altitude, or just the altitude. What i was trying to ask was if they had a formula for coming up with the DA. THat is, 90% humidity and 90 degrees is worth 1000' + the std altitude. Something like that.

Also what are the std conditions for DA, 80 degrees, 50% RH, 14.7 psia (or 29.xx")? I've always just used the numbers that the maple grove weather station spits out, never looked into calculating my own DA and if that was standardized or not.

thanks,
brent