whats better

[screamer69]

what better running vac hose on fuel pressure reg or running a static pressure this is for a turbo car with 440cc injectors

cheers

[jakobsladderz]

Assuming that you have port injection, the following comments apply. For throttle body injection (or any form of injection) the reference pressure for the pressure regulator should be the same point the injectors spray into, but the comments still apply..

Definately manifold pressure referenced. this way, as the boost goes up then the fuel pressure goes up to match it and the fuel flow per unit time stays contant. This will make mapping easier too (compared with the alternative).

Without the manifold pressure reference the pressure across the injector decreases (means lower fuel per time) as the boost increases, which is the exact opposite of what you want.. In the same vein, if the manifold pressure goes down (idling) the pressure difference increases across the injector so the fuel flow/time increases. As you can see, the effect of not referencing the fuel pressure to the injector nozzle pressure is a greatly increased pulsewidth range required from the injector as the injector pulsewidth has to compensate for both the engine requirements and the changing injector flowrate. Not recommended.