<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by utahviper:
I have run two or three times in the past 3 years at rocky mountain raceway in SLC, UT and I don't know if I am running good times or not. The elevation is ~4500 ft.I run between 13.1 and 12.79 @112-114 mph in the summer, I have never run it during the winter. ................... There was a pilot there, at the track, who said the corrected elevation was 7400ft when changing the other factors to their constant. So I put that in at the website and it gave me an 11.68. Somebody please educate me.
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That's a very high elevation as I am sure you know. Normally, drag racers look at DA (density altitude) or OA (oxygen altitude). If I'm being too simple, please excuse me. The thickness of air (ie oxygen content) of the air has a drastic impact on the way normally aspirated cars run. The thicker the air, the better. The closer to sea level you are, the better they run. This is one reason why so many NHRA records are set in Houston and Gainesville. The optimum setup is low elevation, low temp, high barometric pressure, and low humidity. It's typical that the DA or OA will be much higher than the elevation alone. For instance, I race in West Texas. The elevation in San Angelo is 2000 ft above sea level. During the summer when there it's hot and humid, and especially if we have a low pressure weather system in the area, I'll see density altitudes of 5000 to 6000 ft DA. Horrible air. Although it is not completely accurate, the rule of thumb is 1 tenth second ET per 1000 ft. density altitude. Of course that can vary. I ran a 9.17 in San Angelo one weekend at 5000 ft DA and the next weekend ran in Dallas (Texas Motorplex) with 1200 ft DA and posted an 8.82. (almost 4 tenths). Those lucky guys in Houston in the spring time!!!!!! Those guys get to run in air that is sometimes -1000 ft DA. Yeehi!
Forced induction motors (blown and turbocharged) react less to 'bad air' than a normally aspirated motor. Nitrous motors are in the same category as they make their own atmosphere with the introduction of No2 into the induction system.
Now, to answer your question about if a 13.1 to 12.79 is good or not. Yes, it's very good. In 6000 ft of air with my Viper on street tires, I ran a 12.67. My car has Belanger headers, 3" exhaust, and K&N's. (Granted, I spun like hell)
Bottom line, don't feel bad about a 12.79 in 7000 ft. of air. If all those guys that are running in good air came and raced with you and me, they sure wouldn't be posting the same numbers they do at their home tracks!
Hope that helped a little anyway....
Happy Motoring.
