Fuel Injector Flow Calculator
SI
Imp
Imperial
Inputs
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Engine power
(P)
Target crank or wheel power. Match BSFC to the same basis.
hp
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.
lb/ft³
Rated pressure
(P_r)
Pressure differential used for the injector published rating.
psi
Target pressure
(P_t)
Fuel pressure differential in the intended system.
psi
Results
Default result
Edit inputs
Required injector rating
331
cc/min
Pass
Also computed
Total fuel volume flow
0.5939
gpm
Total fuel mass flow
3.693
lb/min
Per-injector mass flow
0.5431
lb/min
Pressure flow factor
1.000
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.
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