Iron Lung

iTrader: (6)

Well I have a few bugs to work out but I got a pretty good preview of the gains. I tried a 50 shot at first and it felt decent but the fuel pressure was past 100psi. Thats with the .042 bypass. So I put the .036 nitrous jet in there and tried it again and no suprise the pressure remained the same at 100psi. I'm gonna have to try the local shops to see if I can get some by-pass jets. Hopefully by Thursday(Track Day).

Can anyone recommend what jet to start at for bringing the pressure down?

Ramius83

Until you get the proper jet sizes, I wouldn't use the nitrous. At 100 psi on stock injectors, you can lock them up. That would be bad, ask Brian V about that......

mtrai760

iTrader: (19)

Wow, that is really high. You can also damage your engine by introducing that much fuel and not burning it... Did you install an aftermarket fuel pump? You may have to go to a .070 or higher to get your pressure down... ;(

My 4DSC

changing the nitrous jet will not affect the fuel pressure at all...
just put a bigger bypass jet in, bring the FP down to 85psi and run a 100 shot.

PS: get a bunch of jets, try .055/65/75/85 to start or take smaller steps if you got the money...

Iron Lung

iTrader: (6)

Ok I took out the Fuel bypass just to see what the pressure would be(I unhooked the ground on the second solenoid) and it was at 78psi. Is there anyway to get this down from here or I am just stuck with running a higher shot.

I have the walbro high pressure pump

mtrai760

iTrader: (19)

Do you have a new fuel pump?

Iron Lung

iTrader: (6)

Yeah I have the walbro High pressure. Should I have not gotten the high pressure pump?

BriGuyMax

iTrader: (1)

the only way left is to get a adjustable FPR and turn it down manually. I tried all the way up to a .082 bypass jet and my pressure still wouldn't come below 85psi with the walbro pump....

Iron Lung

iTrader: (6)

I am a little confused as to how the FPR works for adjusting fuel pressure for both N/A and nitrous. Oh and My pressure N/A is 35psi and 43psi.

BriGuyMax

iTrader: (1)

if you turn down your baseline idle fuel pressure....the full throttle AND "on nitrous" fuel pressures will come down.

For example turn the idle down to 32-33 and your "on nitrous" pressure could come down 5-8 psi

Iron Lung

iTrader: (6)

OK I see now. But if i run a lower N/A fuel pressure will that harm the motor? And since I am running at 78psi what if I just use an 80 shot jet. That should be about the right pressure, right?

Ramius83

Well, when running NA, your ECU should compensate a little for the "leanness" in the engine. However, did you see a fuel pressure jump when you installed the Walbro when NA? I noticed a 10 psi jump. So, if you bring it down with the adjustable FPR 10 psi, that should be a start on bringing it down.....

Iron Lung

iTrader: (6)

The NA pressure was exactly the same on the walbro as the stock pump. Oh and I just tried out the 80 shot and I pulled the plugs and they looked fine, but the nitrous surges sometimes. I did three runs in 2nd and only once was a continuous surge.