Boost Referenced FPR help
Boost Referenced FPR help Hi all just hooked up my Boost referenced FPR.
Prior to hooking it up my FP was 58 with it hooked up it dropped down to 45 and even 40 when idling.
I didn’t get the numbers driving but is this normal?
Is this due to VaC?
The motor is a 430LSX with a procharger F1R, fast 102, nw 102 etc
Prior to hooking it up my FP was 58 with it hooked up it dropped down to 45 and even 40 when idling.
I didn’t get the numbers driving but is this normal?
Is this due to VaC?
The motor is a 430LSX with a procharger F1R, fast 102, nw 102 etc
yes its normal..
with the vacuum line unhooked and the pump on, make sure the pressure is at 58 psi. Once you hook the vacuum gauge on, the fuel pressure should drop depending on the amount of vacuum you pull.. that is because the injectors need less pressure as it is injecting into an engine with no pressure in the intake portion of the tract(in reference to atmospheric). Hence why whenever the intake manifold sees 103ish kpa=sea level pressure, same pressure you set your regulator with the vacuum line unhooked, you will see 58 psi. If you see 5 psi of pressure inside your manifold, the regulator will add 5 psi of fuel pressure to the existing regulated value, to make 58+5=63 psi of fuel pressure to counteract the pressure inside the manifold pushing up against the fuel with a pressure of 63 psi trying to go down into the back of the intake valve.
That's the best I could explain it.
with the vacuum line unhooked and the pump on, make sure the pressure is at 58 psi. Once you hook the vacuum gauge on, the fuel pressure should drop depending on the amount of vacuum you pull.. that is because the injectors need less pressure as it is injecting into an engine with no pressure in the intake portion of the tract(in reference to atmospheric). Hence why whenever the intake manifold sees 103ish kpa=sea level pressure, same pressure you set your regulator with the vacuum line unhooked, you will see 58 psi. If you see 5 psi of pressure inside your manifold, the regulator will add 5 psi of fuel pressure to the existing regulated value, to make 58+5=63 psi of fuel pressure to counteract the pressure inside the manifold pushing up against the fuel with a pressure of 63 psi trying to go down into the back of the intake valve.
That's the best I could explain it.
You must think of pressure in terms of "absolute" pressure. This means that the 0 pressure of everyday living is really closer to 15psi. Intake manifold vacuum will be somewhere between that and 0. An ideal vacuum would pull your 58psi base pressure down to 43psi to achieve a net 0 difference.
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