How do I figure what fuel pressure to run?

Hey guys, I'm about to install my Megan FPR, but I was wondering what fuel pressure I need to set it at. My the car/mods are listed in my sig. Can anyone give me a clue? Thanks.

37.5 vac dissconnected...

Thanks... now is that with the vacuum disconnected from just the regulator? And how did you come up with that figure, or is it just common knowledge? And when would I want to increase my fpr? Thanks for the patience... still new to some of this.

well, I don't know anything about the Megan racing fuel pressure regulator. So I can't tell you how to adjust its spring pressure. FPR's use vacuume/boost to regulate the amount of pressure flowing through the fuel rail, and uses a ruturn port for excess fuel to be pushed back into the fuel tank. It's extreamly improtant to have the correct BFP for fuel trims. The ECU caculates IPW on base fuel pressure.. Setting BFP on a my Aeromotive 13109 requires untighting the nut on top of th regulator and using an allen wrench to compress/uncompress the spring, untill the desired BFP is seen on my fuel pressure gauge that is attached to my regulator.

When you set your fuel pressure you disconnect the vac line that runs to the regulator to astablish a "base fuel presure" at 0 vac. Then when you connect your vacuume line you will notice a change fuel pressure. 1psi for ever 2 in/hg of vac.. Thats why you set BFP with the vac disconnected...

2g 43.5psi bfp vac dissconnected
1g 37.5psi bfp vac dissconnected

That is with the hose disconnected, IIRC with the vac hose its 43 on a 1g turbo. Both numbers can be found in a shop manual so if you dont have one, I would suggest getting one. Also, FPR stands for Fuel Pressure Regulator, not fuel pressure, but I dont know when you want to raise the pressure on that.

You want to raise fuel pressure to compensate for high IDC. Increasing BFP will bandaid maxed out injectors.. IIRC stock 1g/2g are only accurate on their 1:1 boost refrences to 66psi bfp..

stock 450cc at 43psi BFP at the factory enrichment +55% over 2.1g/rev will net you a max of 29lb/min airflow @ 100%IDC. Increasing BFP to 50psi will give you 29lb/min ariflow at 94%IDC..