SureShot

I want to push up the fuel pressure just a bit.
An aftermarket FPR should be a simple install.

1) So how do you get around the old stock FPR that's welded on the secondary rail?

2) Any traps/problems just installing it down stream of the stock FPR if it's set at a higher pressure?

3) Will it's pressure readings even be accurate?

Aaron Cake

iTrader: (1)

Cut the stock FPR off and weld on the appropriate fitting. You can also leave the nipple open to the air which essentially disables the FPR, but that's kind of ghetto.

Icemark

Hmm, you might try a S4 rail, as the FPR is bolted onto that.

Not sure how close the injectors line up though

daten

Are the bolts spaced the same on the S5 and S4 turbo rails?

I know they are not compatible on the NAs.

I couldn't get a fitting welded on the stock rail, something weird with the metal.. eventually got it on and it leaked when we pressure tested it. So I had someone make me a custom rail. =)

SureShot

I am OK with a getto-rig as long as it looks finished.
Maybe if I put a cap on the old vac nipple, until I can cut the old FPR off & braze on a cap steel in place of the whole thing.

Has anyone tested the old FPR with the vac line off?
Will the idle pressure be low enough?

Digi7ech

iTrader: (1)

A S4 fuel rail will fit on a S5 LIM.
You'll need to use a washer or two to make the injectors not get crushed by the rail( a few mm shorter than a S5 rail)

The S4 rail has a bolted in FPR. Just remove it and then get an adapter.
Reted's parallel fuel diagram has the exact parts. I think it's a 12mm x1.5thread on the fuel rail.

slpin

iTrader: (9)

actually, that would make the FPR give fuel for 0psi....

Aaron Cake

iTrader: (1)

Uh huh, 0 PSI = atmospheric. At atmospheric pressure, the fuel pressure in the system is static. The aftermarket FPR then assumes the role of the factory FPR and lowers/raises pressure accordingly.

SureShot

My guess was that the stock FPR drops the pressure at high vacuum like it does on the NA's.
It's probably a non issue since I was planning to set the idle pressure to 35PSI.

(Please - let me win that e-bay auction on the wide band UEGO)

Aaron Cake

iTrader: (1)

Exactly. Pressure drops under high vacuum to compensate for the amount of fuel that the vacuum will suck out of the injector. Pressure increases under boost to compensate for the injectors having to spray into a pressurized area. Atmospheric is about as neutral as it gets, but it really isn't a huge amount of trouble to weld/braze a fitting onto the stock rail.