Injector Size Calculator
Injector Flow Rate Estimator
Size (cc/min) = (HP × BSFC × 10.5) ÷ (Cylinders × Duty %)
Determine the required injector size based on horsepower target, fuel type, fuel system load, and boost options.
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Understanding Injector Sizing
Selecting the correct fuel injector flow rate is critical to matching your engine's power target without running out of fuel supply or overloading the injector's solenoid.
Brake Specific Fuel Consumption (BSFC)
BSFC represents the pounds of fuel consumed per hour per horsepower. Boosted setups require higher BSFC due to richer safety targets, and alternative fuels like E85 require significantly higher volume to produce equivalent power.
Safety Limits:
- • **Duty Cycle:** Never exceed **85%** duty cycle under peak load to prevent the injector from locking open or overheating.
- • **Fuel Pressure:** Lower effective pressure under boost in fixed-pressure systems reduces flow, requiring larger injectors.