Work out injector size instantly with clear inputs, formula shown and shareable results.
Injector sizing works from brake specific fuel consumption: total fuel flow is power times BSFC, divided by cylinders and by the maximum duty cycle you will allow. Keeping duty at or below 85% leaves margin for injector response and prevents the pintle from staying open.
Injector sizing
lb/h per injector = power x BSFC / cylinders / duty cycle; cc/min = lb/h x 10.5
About 0.45-0.50 lb/hp/h for a naturally aspirated petrol engine and 0.55-0.65 for boosted, since forced induction engines run richer.
Above that the injector has little closed time, flow becomes non-linear and heat soak affects it. Static (100% open) operation loses all metering control.