Fuel Injector Calculator
Find the injector size and fuel pump flow your power goal needs, on gasoline or ethanol.
Quick picks
Number of injectors
Fuel
Engine
Injectors are sold rated at a pressure (usually 43.5 psi), and what sets their flow is the pressure across them. With a 1:1 boost-referenced regulator, enter the base pressure: rail pressure rises with boost, so the difference stays the same. With a fixed or returnless system, enter rail pressure minus your peak boost.
Minimum injector size
Minimum injector size: 788cc/min
75 lb/hr @ 43.5 psi
Smallest standard size
Smallest standard size: 850cc
at or under your max duty
Fuel pump
Fuel pump: 180L/h
flow needed, with 20% margin
850 cc · 4 injectors
74%
Green is under your max duty. Past 95% the injector is nearly always open and cannot add fuel.
Duty each size would run at your target, and the most power it supports at your max duty. Tap one to see it on the gauge.