Fuel Pump Calculator

Your details

Enter your peak flywheel (crank) power target. Use the maximum value the engine is expected to produce, not an average.
HP
Brake Specific Fuel Consumption (BSFC) varies with induction. Forced induction engines consume more fuel per unit of power.
Ethanol and methanol blends have different densities and energy content, which affects how much volume the pump must flow to deliver the same energy.
Optional. Enter a known BSFC value from a dyno sheet. Leave at 0 to use the standard value for the selected induction type.
lb/HP/hr
A 15-20% headroom buffer prevents the pump from running at 100% duty cycle, which shortens its life and causes fuel starvation at peak demand.
%
Return systems reference fuel pressure to atmosphere, so boost pressure adds directly to pump workload. Returnless systems reference to manifold pressure, so the pump works harder at idle than at boost.
The fuel pressure at the injector rail with the engine off or at idle (no boost). Typical values are 43-58 PSI for port injection and 200-2000 PSI for direct injection.
PSI
Peak manifold boost pressure for forced induction engines. Leave at 0 for naturally aspirated. On a return-style system, this adds directly to the pump pressure required.
PSI
Minimum flow rateStock-replacement range
136.3LPH

Litres per hour the pump must deliver, including safety margin

Flow rate (GPH)36GPH
Mass fuel flow216lb/hr
Effective pump pressure43PSI
BSFC used0.45lb/HP/hr
Min flow (LPH)136.3
Mass flow (lb/hr)216
Effective pressure (PSI)43

Size your fuel pump to at least 136 LPH at 43 PSI.

  • Your engine needs at least 113.6 LPH of fuel at peak power. With the 20% safety margin, size your pump to at least 136.3 LPH (36.00 GPH).
  • At 0.450 lb/HP/hr BSFC, the engine burns 216.0 lb of fuel per hour at 400 HP. This is a mass-based figure; your pump rating is volume-based, so fuel density matters.

Next stepCross-check the required flow against the pump manufacturer's pressure-flow curve at your effective pump pressure, not just the headline LPH rating.

 = Powered by OnlyCalculators