Enter your Injector Rated Flow Rate, Rated Fuel Pressure, and New/Actual Fuel Pressure into the Fuel Injector Pressure Calculator to find your New Flow Rate — along with the Pressure Ratio, Flow Change, and Flow Rate in LB/Hr — so you know exactly how much fuel your injectors are pushing at any given pressure.
New Flow Rate
--
Flow Rate (LB/Hr)
--
Pressure Ratio
--
Flow Change
--
Fuel injector flow rate is proportional to the square root of the fuel pressure. Higher pressure increases flow rate, while lower pressure decreases it. This relationship follows the formula: New Flow = Original Flow × √(New Pressure ÷ Original Pressure).
Most fuel injectors are rated at 58 PSI (4 bar) fuel pressure, though some manufacturers use 43.5 PSI (3 bar). Always check the manufacturer's specifications for the exact test pressure used for your injectors.
This calculator determines flow rate based on pressure changes and works for any fuel type. However, different fuels have different energy content, so you may need different flow rates for the same power output when switching between gasoline, E85, or methanol.
You might run different fuel pressures than the injector's rated pressure due to fuel system design, altitude compensation, or when using aftermarket fuel pressure regulators. This calculator helps ensure you have adequate fuel flow for your application.
This calculation is very accurate for the flow rate change due to pressure differences. The square root relationship between pressure and flow is a fundamental fluid dynamics principle that applies to all fuel injectors.
CC/min (cubic centimeters per minute) measures volume flow, while LB/Hr (pounds per hour) measures mass flow. The conversion depends on fuel density, with gasoline having approximately 1 lb/hr = 10.5 cc/min at standard conditions.