fuel pressure education

[ArtMan]

I often wondered why the stock fuel pressure is 39 psi too. I'll bet it has something to do with the injector design rather than the fuel pump design. In any case, that's what Ford has decided all stock EECs will assume is present at the injectors. When you increase fuel pressure through the use of an adjustable fuel pressure regulator more fuel flow occurs. The computer doesn't detect this during Wide Open Throttle operation, because the O2 sensors are shut off.

This extra fuel can produce extra horsepower if accompanied by extra air. But there's a limit. Increasing fuel pressure excessively degrades the spray pattern of the injector and poor fuel delivery can occur. So, I'm not sure if you can effectively turn 19# injectors into 24s. The relationship between pressure and flow is not linear.

Generally, if you feel the need for 24# injectors you should just upgrade, because you will likely do other mods that require them. Fooling the computer just goes so far.