Fuel pumps are rated at a specific pressure and voltage. As pressure increases or voltage drops, flow decreases. A 20% headroom factor ensures your pump can handle real-world conditions.
For boosted applications, fuel pressure rises with boost if using a 1:1 regulator. A 10 psi boost increase raises fuel pressure by 10 psi, reducing pump flow.
255 LPH (67 GPH): Walbro 255, common for mild builds up to ~400 HP naturally aspirated.
340 LPH (90 GPH): AEM 340, good for ~500 HP naturally aspirated or ~350 HP boosted.
450 LPH (119 GPH): Walbro 450, supports ~650 HP naturally aspirated or ~450 HP boosted.
525 LPH (139 GPH): Walbro 525, supports ~750 HP naturally aspirated or ~525 HP boosted.
Always check the pump's rated flow at your target fuel pressure, not just the headline number.
fuel pump calculator, fuel pump sizing, LPH fuel pump, GPH fuel pump, horsepower fuel pump, walbro 255, walbro 450, fuel pump headroom, boost fuel pump size
I'm always improving these calculators. Let me know what you'd like to see next.
No spam. Just feedback to improve the site.