CLASS RACER FORUM - ET Prediction Calculations

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ET Prediction Calculations

Does anyone out there have a spreadsheet or the formulas for determining ET based on changing weather conditionsf or a gas powered car? My Sharp programmable calculator bit the dust. I simply entered Temp, Humidity and Barometric Pressure into it and it gave me a factor that I could use to compare to old runs and factors to determine my new ET. It worked great. I know this stuff is not rocket surgery, but I can’t find any resources online.
Thanks Rusty

Re: ET Prediction Calculations

Google "Max Race Software". Larry has a nice ET prediction program, it is very specific on all inputs and it does a nice job.

www.maxracesoftware.com

Larry may have taken his free version down. If you cannot find it, you might try emailing him.

Re: ET Prediction Calculations

Quote:

Originally Posted by Redlight (Post 139742)

These should help: http://www.wallaceracing.com/Calculators.htm

http://www.wallaceracing.com/convert-et-to-msa.php

Maybe I'm doing it wrong, but I input 1st run of 9.40 @ 141 at 300' elevation, 70°, 45%, and a 2nd run of 2500' elevation, 80°, 45%, and it predicted I would run 9.29 @ 142.72!!!

I created a spreadsheet to do Density Altitude calculations (I'm too cheap to buy a real weather station that does it for me). It is a combination of stuff I found in textbooks and the internet, with an additional factor added to make it match NHRA's value (when they post Density Altitude on their racing results pages). Here is the cell formula:
=(44.3308-11.1802*((D3*3386.389/((((D1-32)*5/9)+273.15)/(1-0.378*((6.1078*10^((7.5*((D1-32)*5/9))/(237.3+((D1-32)*5/9))))*(D2/100)/(D3*33.8693)))))^(0.234969)))*3280.8333+(550+((44. 3308-11.1802*((D3*3386.389/((((D1-32)*5/9)+273.15)/(1-0.378*((6.1078*10^((7.5*((D1-32)*5/9))/(237.3+((D1-32)*5/9))))*(D2/100)/(D3*33.8693)))))^(0.234969)))*17))

D1 = temp °F, D2 = humidity as whole #, D3 = barometric pressure in-hg

It's not perfect, but it comes pretty close to NHRA's and the other commercial weather stations. I use it with a cheapo electronic weather station that has temp, humidity and pressure.

Regards,
Michael Pliska