[Redline Motorsports]

Selecting the Proper Injector

In order to select the correct size injector for your application, you might wish to use one of the following formulas.
In most cases a naturally aspirated engine will have a B.S.F.C of .50. This means that the engine will use .50 lbs. of fuel per hour for each horsepower it produces. Turbocharged engines will want to be at .60 lbs. per hour or higher.

Using these numbers as a guideline, you can select the approximate injector size in the following formula for a eight cylinder, naturally aspirated engine at 600 bhp.

Most injectors will max out at 80% duty cycle and this is the accepted industry standard.

B.S.F.C is brake specific fuel consumption - How much fuel you are using per horsepower per hour

(HP x BSFC)/(# of injectors x max. duty cycle)= lbs/per hour

(600 x .45)/(8 x .80)

(270)/(6.4)= 42 lb/hr injector

The proper injector for this application would be 42 lbs. / hr. or 441 cc / min. NOTE: the .45 BSFC was based upon a GEN style motor. These motors are extremely efficient which reduces this value.

To convert cc / min to lbs. / hr. - Divide by 10.5
To convert lbs. / hr to cc / min - multiply by 10.5


To convert lbs. / hr to gal. / hr - Divide by 6


To convert cc / min to gal. / hr. - Multiply by .015873