Injector Duty Cycle (IDC) represents the percentage of time the injector is open during a single engine cycle. It is standard industry practice to size injectors so they do not exceed 80-85% at peak demand. This 'headroom' is vital because injectors need a small amount of time to physically close and cool their internal solenoids. Running at 100% (static) can lead to overheating, coil failure, and inconsistent fuel delivery as the spray pattern becomes unpredictable.

The type of fuel you use significantly impacts the required injector size. Ethanol (E85) has a lower energy density than standard pump gasoline, meaning you must spray more volume to achieve the same power output. Typically, an engine running on E85 requires approximately 30-40% more fuel flow than one on gasoline. Our calculator applies a 1.3x multiplier for E85 to account for this increased volume requirement.

Brake Specific Fuel Consumption (BSFC) represents how much fuel an engine consumes to produce one horsepower for one hour. Naturally aspirated engines are generally more efficient (lower BSFC, ~0.45-0.50), while forced induction engines (Turbo/Supercharged) require more fuel to cool the combustion chamber and prevent knock (higher BSFC, ~0.60-0.65).

When selecting injectors, it's often wise to choose a size that allows for future performance upgrades. If your current goal is 300 HP but you plan to add more boost later, calculate for your 'end goal' HP. Larger injectors won't hurt performance as long as your ECU can accurately control them at very low pulse-widths (idle).