Fuel Injector Sizing Formula - HP x BSFC Calculation & lbs/hr to cc/min Convert

This document is a single-page reference showing the formula for calculating required fuel injector flow rate. The formula shown is: Horsepower multiplied by B.S.F.C (brake specific fuel consumption), divided by the number of RC injectors multiplied by .80 (duty cycle). A worked example is provided: 200 (horsepower) multiplied by .50 (B.S.F.C), divided by 3.2 (which represents the number of injectors times the .80 duty cycle), yielding 31.25 lbs./hr. per injector. The document also shows how to convert the result from pounds per hour to cubic centimeters per minute: 31.25 multiplied by 10.50 equals 328 cc/min. A reader can learn how to size fuel injectors for an EFI engine based on target horsepower, an assumed brake specific fuel consumption value, injector count, and an 80% duty cycle safety margin, and how to convert between the two common injector flow rating units (lbs./hr. and cc/min). The document contains no vehicle year, make, model, engine, or part number information; it is a generic calculation reference applicable to sizing injectors for any electronically fuel-injected engine.