TORQDEX // ENG-01
Injector Flow Calculator
Estimate the injector flow rate required to support a target horsepower level using BSFC, injector count, and maximum injector duty cycle.
INPUT DATA
RESULT
Enter horsepower, injector count, BSFC, and duty cycle.
01 // BSFC GUIDE
Understanding BSFC
BSFC represents the approximate amount of fuel required to produce one horsepower for one hour.
Naturally Aspirated
A gasoline naturally aspirated engine may often fall around 0.45–0.55 lb/hp/hr. Actual requirements vary by engine efficiency and tune.
Forced Induction
Turbocharged and supercharged gasoline engines often require a higher BSFC value. Values around 0.55–0.65 are commonly used as conservative starting estimates.
Alternative Fuels
Ethanol-based fuels generally require more fuel mass and volume than gasoline for the same power output. Use an appropriate BSFC for the actual engine and fuel.
02 // DUTY CYCLE
Leave injector headroom
What duty cycle means
Injector duty cycle describes the percentage of available time that the injector is commanded open.
Avoid sizing at 100%
Injector sizing is normally performed with some capacity left in reserve rather than assuming the injector can operate continuously at maximum command.
Verify the fuel system
Injector capacity alone does not guarantee adequate fuel delivery. Fuel pressure, pump capacity, voltage, regulator performance, and injector characterization also matter.
FORMULA
Injector flow
Total Fuel Flow = Horsepower × BSFC
Injector Flow = Total Fuel Flow ÷
(Injector Count × Duty Cycle)
Duty cycle is converted from a percentage to a decimal. For example, 85% = 0.85.