Air Density Online

weather calculations for racing engine tuning


Jet your car from anywhere with an internet connection. Have a smartphone? You now have a portable jetting calculator.

for tracks

Real-time density altitude from current weather data at various tracks including: NHRA & IHRA dragstrips, road courses, dirt ovals.


Get your MFI fuel system setup programmed into ProCalc. Even get your dyno data added. You get 1 year of access to ProCalc too!

Thanks for visiting our site. We provide real-time, historical, and forecast weather data for racing engine tuning. We also provide engine tuning tools for mechancial fuel injected racing engines. We are constantly adding tracks to the site. If you'd like to see your track added to the list, send it over. Learn more about this site and it's creators or read some of the articles we've written.

What's New

September 10, 2020

Add your track weather to your phone home screen

We recently updated our article on adding your favorite track's weather page to the home on your iPhone. This way you have an icon on the home screen for quick launch directly to the track weather page. No more scrolling through the long list.

Get Quick Access to Weather At Your Favorite Track

August 20, 2020

Weather Accuracy in Engine Tuning with Handheld Weather Stations

Kestrel at the track

Using a handheld weather station at the race track

Throughout the years, we've seen many racing teams documenting their engine specs after a run.  Fewer teams keep meticulous records of the weather they experienced during that run.  It seems obvious to note that it’s hot and humid or windy.  Perceived weather and actual measured weather could provide conflicting information.

In open drag racing competition such as Top Alcohol, the tuning goal for maximum performance is to get the pistons so hot that oil is burnt on the underside.  This is a smidgen away from piston dome melting damage.

(read more...)

August 10, 2020

Some kind words from Bill Drevo Jr

Bill Drevo's race car

Bill Drevo's drag car

You're WEB site just makes so much common sense for the drag racer and other types of motorsports activities. One things that I like about it is the 'water grains' can't displace water with gasoline! There was an interesting weather situation which occurred at the recent NHRA race at Dinwiddie, VA that I had never seen before. There was a large 'Bermuda High' located in the Atlantic ocean about 400 miles SE of Dinwiddie. Because of it's clockwise rotation it was pushing air with high humidity over the whole SE USA. However, by the time that air had reached the Dinwiddie area, the relative humidity percentage was only reading in the mid-40s. But, the water grains number was in the mid 80s. I theorized that this disparity between the relative humidity percentage and the water grains number was due to the fact that as the high humidity air spread across the SE US it dissipated to that point, but because a water grain is a more solid form of H2O it didn't dissipate nearly as much, thus the resulting high number. (read more...)

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