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How to size fuel pump

EFI Tuning Fundamentals

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From BSFC video I remember that you can easily calculate minimum necessary injector size. But how about minimum neccesrey fuel pump capacity (liters/min at working pressure)?

As I understand, then it should be quite larger than injector flow rate. As otherwise there would be no fuel in return line, as all the fuel would drain through injectors, also there would be enough material to maintain neccesrey pressure.

So the question is at least how many times larger the fuel pump capacity has to be?

I normally allow for a 25-30% oversupply at the rated fuel pressure. Take your injector flow at 100% IDC (at whatever differential pressure you're running), multiply by the number of injectors and then multiply by 1.3 for example. It's really important though to make sure that you're taking note of the flow the pump can support at the actual operating pressure since this will drop dramatically as the pressure increases.