Fuel Pump Flow Calculator

How many litres/hour your pump must flow for a target power — petrol or E85.

How it works

1

Enter power & fuel

Crank HP and fuel type (E85 needs far more flow than petrol).

2

Add a margin

20% headroom is sensible so the pump is not at 100% duty at peak power.

3

Size the pump

Get the required flow in L/h — choose a pump rated above it at your system pressure.

Frequently asked questions

How is fuel pump flow calculated?

Fuel mass = HP × BSFC (lb/hr), converted to litres using fuel density (petrol ≈ 0.745 kg/L, E85 ≈ 0.785 kg/L), then a safety margin is added.

Why does E85 need a bigger pump?

E85 has a higher BSFC and you burn much more of it, so the same power needs roughly 30–40% more volume per hour than petrol.

Pump rating vs real flow?

Pumps are rated at a test voltage and pressure; real flow drops at higher rail pressure and lower voltage. Always pick a pump comfortably above the calculated figure.

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