Select the number of injectors you are using(generally 1 per cyclinder).
Select the approximate BSFC of your car. Brake Specific Fuel Consumption is
the amount of fuel, per hour per horsepower, that an engine consumes. Non turbo
engines are generally around 0.5 BSFC, while turbocharged engines are generally
around 0.65.
Select either your horsepower rating or your injector size.
Injector sizes are in cc/min.
Specify the duty cycle the injectors will be run at. 0.8 - 0.85 should
be your goal at full boost and maximum engine speed. Higher duty cycle and
your injectors can overheat, flutter, and all sorts of other nasty things.
Click the button, and your maximum horespower or your required injector
size will be calculated.