Drag Racing Wheather???

[96cobravert]

You know I have been drag racing (for fun) for a number of years, but i'm embarrassed to admit I have no idea what to look for when it comes to "good air"?? Anyone care to share what to look for to get the elusive "good air" and maybe a link to bring my racing weather IQ to where it should be!!!:nabnas:

[PNY UP]

No such thing as a stupid question, unless you don't ask it.

"Good air" is basically a combination of a very low humidity, low ambient air temperature, and a low atmospheric "ceiling" (if I remember right on the last one). These factors (and probably a few more- feel free to correct/add if I am wrong here) are used to calculate a number known as the "DA" or Density Altitude. It is the same number/calculation used by airplane pilots to determine (among other things) distance and speed needed to create enough lift for takeoff.

For the DA number, the lower the number the better the "air". At the track, they can tell you what the DA is at any point during the day if you want to record the data on your timeslips for future reference. I simply record the temperature and guesstimate the humidity, I'm not in need of the level of data where the exact DA and wind direction are needed. It's really more of the data geek in me wanting to analyze a little more information.

Over the last few years, I have basically figured and proven to myself that every 10 degree rise in ambient air temp cost me about a tenth of a second in ET, unless it was extremely humid or dry, then the results would vary more from that general rule of thumb.

Hope that helps.

[Kinger]

Here is the info to figure the air quality and pretty much any info you need!

I've been trying to put this together for a few days now and finally got all the links. DA is something a lot of may not take into account when we're racing, but it's very important. Every 10 degree shift in temperature can effect ET/MPH approximately .1/1
DA takes into account air temperature, altitude, humidity and barometric pressure.
anyway.... here ya go!

First you need to get the weather conditions of the track when you ran and the altitude of the track. this site will give you an hour by hour history as far back as you want to go.

you can find weather at:
http://www.weatherunderground.com

then input the values into either of these calulators to get the Density Altitude:
http://wahiduddin.net/calc/calc_hp_dp.htm
or
https://www.beaufort.usmc.mil/weather/density_altitude_calculator.htm


now reference this graph to calculate your density altitude to 0 for a fair comparison of track times:
http://www.gnttype.org/techarea/misc/altitude.html

or
this site is a little more user friendly
http://www.modulardepot.com/density.php

you can find exact elevations with this tool

http://nmviewogc.cr.usgs.gov/viewer.htm

EDIT:
altitudes
KCIR - 798
MOKAN - 912
WIR - 1348
HPT - 1050
GIR - 405
SAR - 600

[PNY UP]

Gee whiz....and I thought I was anal. :hail:

[Kinger]

Gee whiz....and I thought I was anal. :hail:

Naaaa, it's a copy and paste from an old Post from a very anal F-body/05 Mustang guy!! LOL John, aka 408SS hehe His fiance' Kellie has that Black 05 with the Bogarts that ran Wild Street last year at the NMRA!!

[PNY UP]

hehe Oh Great. More stuff for me to analyze. Now I have a whole stack of timeslips to go back through. :woohoo:

Now where did I put that pocket protector? It's going to be a long night :smilielol:

[96cobravert]

Wow, thanks guys for the great info. Plannin on going to the track tommorow night, go weather??