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Fuel pump
The pump must handle the flow at the real system pressure, not just on paper. Enter the target power, base pressure and boost, and you get the demand in l/h plus a recommendation with a margin.
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Required fuel flow
190 l/h
Size the pump for the real system pressure (base pressure plus boost). The flow falls as the pressure rises.
How the calculation works
The fuel demand follows the power. Target power times BSFC gives the mass flow in pounds per hour, which we convert to litres per hour for petrol. A pump that only just meets the demand on paper rarely holds up in practice, so we also show the flow with a 30 percent margin.
Do not forget the pressure. A pump's curve falls as the pressure rises, and with a rising-rate regulator the fuel pressure increases 1:1 with the boost. Always size the pump for the real system pressure at full power, not for free flow.
Example
500 hp with a BSFC of 0,6 needs about 190 l/h, and with a 30 percent margin the pump should handle around 245 l/h at system pressure.
Margin and pressure
| Situation | Recommendation |
|---|---|
| Street | size 20% over target power |
| Race | 30% over target power |
| 800 hp and up | consider dual pumps |
| Base pressure EFI | approx 3,0 bar (43,5 psi) |
| Boost | added 1:1 to the fuel pressure |
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Common questions about fuel pump
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