Injector Size Calculator
Calculate the required fuel injector size (cc/min or lb/hr) based on horsepower, BSFC, and number of injectors.
How It Works
Enter target horsepower, brake specific fuel consumption (BSFC), number of injectors, and maximum duty cycle. The calculator returns required injector flow rate in both cc/min and lb/hr.
Formula
Injector Size = (HP x BSFC) / (Injectors x Duty Cycle)
Frequently Asked Questions
What is BSFC?
BSFC (Brake Specific Fuel Consumption) is a measure of engine fuel efficiency expressed as lb of fuel per hour per HP. Naturally aspirated gasoline engines typically run 0.45-0.55 BSFC; forced induction engines run 0.55-0.65.
What duty cycle should I use?
Most tuners recommend sizing injectors for 80% maximum duty cycle to leave headroom. Running injectors above 90% risks fuel delivery issues and lean conditions at wide-open throttle.