Injector Duty Cycle Calculator

The duty % your injectors run at for a target power.

How it works

1

Enter power & injectors

Target crank HP, number of injectors and their size in cc/min.

2

Pick the fuel

BSFC depends on fuel and aspiration.

3

Read the duty

Keep peak duty under about 85% so the injectors are not maxed out.

Frequently asked questions

What injector duty cycle is safe?

Aim to keep maximum injector duty cycle at or below about 85% at peak power. Running near 100% means the injectors are static (fully open) with no headroom, which risks a lean condition.

How is duty cycle calculated?

Required fuel flow per injector (from HP, BSFC and injector count) is divided by the injector flow rating. The result is the percentage of time the injector must stay open.

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