Fuel Injector Flow Calculator

Inputs

Engine power (P)

Target crank or wheel power. Match BSFC to the same basis.

BSFC (b)

Brake specific fuel consumption. 0.335 kg/kWh is about 0.55 lb/hp-h.

kg/kWh

Injector count (n)

Number of active injectors sharing the flow.

Max duty cycle (D)

Maximum desired injector duty cycle.

Fuel density (rho)

Fuel density. Gasoline is often near 730-760 kg/m3.

kg/m³

Rated pressure (P_r)

Pressure differential used for the injector published rating.

bar

Target pressure (P_t)

Fuel pressure differential in the intended system.

bar

Default result

Required injector rating

331cc/min

Pass

Also computed

Total fuel volume flow2.248L/min

Total fuel mass flow0.02792kg/s

Per-injector mass flow0.004105kg/s

Pressure flow factor1.000

Method notes 2 notes

Flow rating is corrected by the square root of pressure differential ratio.
Final injector sizing also needs fuel type, dead time, ECU control range, rail pressure stability, regulator reference and measured injector data.