Topic says it all. I guess I am disappointed about my 118/119 trap speed in 88 degree heat. How much does the DA and temp really change time and MPH?
Phillip

 

Not sure about the formulas, but here is a start...
http://www.corral.net/projects/blkcld/orlando.html

Here is another interesting link...
http://wahiduddin.net/calc/calc_hp_abs.htm

Density and Density Altitude:

Although the concept of density altitude is commonly used to help express the effects of aircraft performance, the really important quantity is actually the air density.

For example, the lift of an aircraft wing, the aerodynamic drag and the thrust of a propeller blade are all directly proportional to the air density. The downforce of a racecar spoiler is also directly proportional to the air density. Similarly, the horsepower output of an internal combustion engine is related to the air density. The correct size of a carburetor jet is related to the air density, and the pulse width command to an electronic fuel injection nozzle is also related to the air density.

Density altitude has been a convenient yardstick for pilots to compare the performance of aircraft at various altitudes, but it is in fact the air density that is the fundamentally important quantity, and density altitude is simply a way to express the air density
http://wahiduddin.net/calc/density_altitude.htm

 

This one seems to be pretty close to what you are looking for - not sure if DA is equivalent to Altitude
http://www.smokemup.com/auto_math/nh...on_factors.php

NHRA Elevation Correction Factor
##### To convert your timeslip ET and MPH to sea level. Multiply applicable factor times your ET or MPH.

(Example: You ran a 13.8 @ 100 MPH at 5000' elevation track. The correction factors are .9367 and 1.0661 for 5000'. (13.8 * .9367) = 12.93 , (100 * 1.0661) = 106.61 MPH. So the correct timeslip would be 12.93 @ 106.61 MPH.)


Altitude above Sea Level (Feet) Elapsed Time Factor (ET) Trap Speed Factor (MPH)
1200 .9874 1.0129
1300 .9861 1.0143
1400 .9848 1.0157
1500 .9835 1.0171
1600 .9822 1.0185
1700 .9809 1.0199
1800 .9796 1.0213
1900 .9783 1.0227
2000 .9770 1.0241
2100 .9757 1.0255
2200 .9744 1.0269
2300 .9731 1.0283
2400 .9718 1.0297
2500 .9705 1.0311
2600 .9692 1.0325
2700 .9679 1.0339
2800 .9666 1.0353
2900 .9653 1.0367
3000 .9640 1.0381
3100 .9627 1.0395
3200 .9614 1.0409
3300 .9601 1.0423
3400 .9588 1.0437
3500 .9575 1.0451
3600 .9562 1.0465
3700 .9549 1.0479
3800 .9536 1.0493
3900 .9523 1.0507
4000 .9510 1.0521
4100 .9497 1.0535
4200 .9484 1.0549
4300 .9471 1.0563
4400 .9458 1.0577
4500 .9445 1.0591
4600 .9432 1.0605
4700 .9419 1.0619
4800 .9406 1.0633
4900 .9393 1.0647
5000 .9380 1.0661
5100 .9367 1.0675
5200 .9354 1.0689
5300 .9341 1.0703
5400 .9328 1.0717
5500 .9315 1.0731

 

Phil I have observed on my weather station and my car about a tenth per 1000 feet.