Enter your Desired HP Gain, Bottle Pressure, Fuel Pressure, System Type, and Target A/F Ratio into the Nitrous Jet Size Calculator to find your exact Nitrous Jet Size, Fuel Jet Size, N2O Flow Rate, Fuel Flow Rate, and Actual A/F Ratio for a dialed-in setup.
Nitrous Jet Size
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Fuel Jet Size
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N2O Flow Rate
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Fuel Flow Rate
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Actual A/F Ratio
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Most experts recommend running slightly rich at 11.5-12.5:1 for safety. At 250hp and under, you can match your engine's normal A/F ratio. For higher power levels (450-500hp), run 11.5:1 as a safety factor.
Higher bottle pressure increases nitrous flow through the same jet size. As the bottle cools during use, pressure drops and flow decreases. Start with a warm bottle (75-80°F) for consistent pressure readings.
Wet systems inject both nitrous and fuel through the same nozzle, while dry systems only inject nitrous and rely on the fuel system to add extra fuel. Wet systems are generally safer and easier to tune.
This calculator provides a good starting point, but dyno testing with a wideband O2 sensor is highly recommended for final tuning. Engine combinations, altitude, and other factors can affect actual results.
E85 requires different fuel flow rates due to its different stoichiometric ratio. You'll need approximately 30% more fuel flow with E85 compared to gasoline, so use a larger fuel jet.
Jets too small will run lean (dangerous), while jets too large will run rich (power loss and fouled plugs). Always err on the rich side for safety, then fine-tune on the dyno.
Check bottle pressure before each run, and monitor fuel pressure regularly. Low fuel pressure is one of the most common causes of lean conditions and engine damage in nitrous systems.