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Flow Rate Calculator


Flow Conversion

Convert cc/min to lbs/hr


Convert lbs/hr to cc/min

Selecting the Proper Size Injector

Fuel Injector Size Calculator
Horsepower (at the flywheel)
Number of Injectors
B.S.F.C. *
Max Duty Cycle in % **
Required Injector Static Flow Rate @ 43.5 psi lb/hr cc/min

This guideline can help in determining what injector size to use.

* Brake Specific Fuel Consumption: is the amount of fuel consumed (in lbs. per hour) for each horsepower made. This should be .45 to .50 for naturally aspirated engines, .55 to .60 for supercharged engines, and .60 to .65 for turbocharged engines.

** Maximum Injector Duty Cycle should be around 80% max for safe operation. This allows for some future horsepower increases.

Fuel Pressure Modification

By changing your fuel pressure, you can change the flow rates of your injectors.

For example: An injector that flows 330 cc @ 40 psi will flow 369 cc @ 50 psi.

Fuel Flow Calculator
Old Pressure
New Pressure
Old Flow Rate
New Flow Rate

Professional Fuel Injector Calculator
(Idle & Peak Values)

Engine Displacement (CID): C.I.D.
Idle Target RPM: Idle RPM
Peak RPM: Your rev limit may occur before
the peak value.
Peak RPM
Volumetric Efficiency at Idle is typically
10% to 15%:
Number of injectors in the System: Injector(s)
Brake Specific Fuel Consumption
(.5 for 2 Valve, .45 or less for 4 valve):
Idle in Inches of Mercury (In Hg.) If Idle in Kilopascals (kpa): Then kpa / 3.3864 = In Hg " Hg
Expected Peak Horsepower Peak Hp
Millisecond (Ms) Injector minimum open time
(1 to 1.25):
Your Installed Injector size (lb/hr): Lb/Hr
Number of injections per cycle
(batch 2, sequential 1):
How many strokes per cycle (four stroke = 4): Stroke
Injector Size @ 80% recommended duty cycle (lb/hr): Lb/Hr
Max Hp with recommended injectors
@ 85% duty cycle:
Peak Hp
Max Pulse Width Permitted @ 85% duty
at peak rpm: (Ms):
Ms Peak
Max HP with Your Installed Injectors
@ 85% duty:
Max Hp
Idle Millisecond Pulsewidth: Installed Injectors Ms Idle
Projected cc's per minute: Installed Injectors, per injector at idle: cc's / Inj.