measuring vapor pressure for jetsize program. What to use.

I have been using Les Davenport's jetsize program for a few years without measuring vapor pressure or O2 percentage. Trying to get my tune up closer so what is the best way to get that percentage to factor in to Jetsize program?

 

You can find a mathematical model if you make some research on the web and you will be able to translate it to a useful "exel formula" that will place you right on the target everytime.
But like Mr.Canter said: "They also didn't see that it made that much difference. There are too many other factors that made more difference. "
As a starting research link suggestion, see the one below.
Charles Stewart
http://en.wikipedia.org/wiki/Vapour_pressure_of_water

 

vapor pressure & AD available free on-line at www.airdensityonline.com

try www.airdensityonline.com Click on tracks from top right pull down. Select the racectrack currently listed for US and Canada, and get current vapor pressure data. Also air density, density altitude, and grains of water. Also air density forecast. Update is based on national weather service data. So you can calibrate portable weather stations to this site.

Bob Szabo
www.racecarbook.com
916-419-6649

ps On-line jetting calculator, Pro-Calc, also available that provides air to fuel ratio as well as jetting calculations. For example:
- hold nozzles constant, calculate main bypass for air density changes
- hold main bypass constant, calculate nozzles for air density changes
- hold selected nozzles constant, calculate other nozzles for air density changes
- hold fuel pressure constant, calculate nozzles and mainbypass for air density changes
- change air to fuel ratio, calculate, nozzles, main bypass
- change air density, hold air to fuel ratio constant, calculate main bypass, nozzles, etc.