MFI Calc

Engine Tuning & Weather for Mechanical Fuel Injection Racing


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

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What's New

April 17, 2024

Fuel In. Jetting Calc. for Top Fuel, BDK Bypass Valve setups

Our fuel injection calculator can provide a valuable air to fuel ratio (AFR) computation for professional top fuel and normally aspirated A-fuel racing for land or water sports.
  • For example, a typical blown high percentage nitro V-8 setup will have an AFR less than 1 to 1 at the start and lean out to over 1.5 to 1 at the finish of a 1,000 foot drag race. Incremental tuneup changes to the fuel curve can be determined ahead of time with precise numerical references.
  • In a second example, a typical 90% injected nitro V-8 setup will have an AFR less than 0.3 to 1 at the start.  Leanout to keep the 'candle lit' can be numerically determined ahead of time; then set into the fuel bypass controller for numerical control.
Our fuel injection calculator also provides a valuable oxygen to fuel ratio (OFR). Oxygen to fuel ratios (OFR's) from the calculator are a "next level of advance tuning".
  • The oxygen part of the combustion process is determined from all sources: nitro, methanol, blower, & air density.
  • The total amount of the other parts that contribute to combustion are determined from the fuel. That is specifically carbon, hydrogen, & nitrogen that combust.
Nitrogen in the air, excluded from combustion, is also excluded from the OFR calculation, making the OFR tuning value way more affective.

April 2, 2024

We are live!

Welcome to our new site! If you are here from Air Density Online, we're glad to have you!

All links on Air Density Online should now redirect here. We have worked to make this transition as smooth as possible but there may be some hiccups. If you have any issues or if you wish to send any feedback, let us know.

March 11, 2024


Welcome to our new site! If you're new to this site and our partner site,, we're glad you're here. Our sites aim to provide information and tuning tips for racers and engine tuners in the motorsports world. Specifically, we provide information and tools for mechanical fuel injected racing.

If you're here from Air Density Online, this might look a little familiar to you. We hope so! We have kept the new site as similar to the old site as possible in order to make the transition as easy as we can. That being said, we plan on adding new features and making this more useful than the old site.

We will be officially moving all ProCalc & ProTune users over here at the end of this month. We will be in communication with those customers as we go. In the meantime, look around and don't hesitate to send us any questions or comments.

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