New member, new questions. What FP to run?

[Guest CagedVR6]

Well its my 1st post and i new. Anyway i drive a 1997 GTI VR6 with a decent amount of mods, and i plan on turboing it very soon. In the mean time it will be N/A so i have a few questions. Here are my mods 1st.

-Velocity big-valve head (intake and exhaust), ported and polished

-DSR 256 Cams

-JE Pistons 83mm = 2932cc displacement

-Pauter custom con-rods

-high flow in-tank fuel pump and -6AN braided stainless line

-adjustable fuel regulator

-Brospeed header and Autotech cat back

-Eurosport short-ram intake

-TT chip

What Fuel Pressure should i run? Stock Fuel Pressure? If so whats that for my yr? Right now its at about 3.5 bar or 51-52 psi. When under throttle it hits about 60-61psi "rising rate". Is the stock FP reg rising rate?

Anyway thanks.

[cadguy77 0]

the stock reg is not rising rate. my fuel pressure reaches the same figures

[IbiVR 0]

Stock FPR's are fixed rate, they increase the fuel pressure with air pressure at a 1:1 ratio.

It works on vacuum, thats why theres a little hose that comes off the top of it into the inlet manifold.

Inside the FPR is a diaphragm with a valve. At idle when engine vacuum is high, it opens the valve lowering fuel pressure. At higher RPM's when engine vacuum is low, the valve closes increasing fuel pressure.

Your in the USA? There are some odditys with which FPR goes on what VR6 in what country, You tend to run a slightly higher FP over there for OBD1, but I ~think your OBD2 US vr should run a 3 Bar reg stock.

Pull the vac pipe off the FPR at idle and read it then, like i say i think on your car it should be 3 bar, looks like your a little rich, but thats no bad thing, especially for when its turbo.

Tom.

[Guest CagedVR6]

Thanks for the replys. So is my FP cool hitting 60psi when on the gas or is that too rich. I need to get a wideband i suppose. Yes im in the USA. What will pulling the vac line off the FPR do? Thanks!!

[IbiVR 0]

I think you should have a 3 bar reg in there, looks like your running more like 4, but i wouldnt trim it down to far on my say so unless its not runnign right - wideband is defo best bet.

When you at idle you have about 18inHG of vacuum, which is about 1 bar. as the reg is affected by vacuum/boost, it'll be pulling the fuel pressure down. If you pull the vac line off at idle, you'll get a closer idea of what the unadjusted fuel pressure is. Ie a stock 4 bar reg will be giving you just over 3 bar at idle because of the vacuum.

Tom.