Fuel Pressure Regulator

[SilviaSlydSydway]

Hello...Im putting together a turbo kit, but i really need coilovers now. I was going to get a SAFC and run 8 psi, but i need to buy one, and need the money for coilovers. I have SR 370cc injectors, and i want to know what FPR i should get to run about 5 psi until i get a SAFC. Thanks

[jmwenick]

Any, just make sure you get an upgraded fuel pump too. I run the cheap ebay fpr thats like $30 now. It works pretty good, I have fuel pressure at 40psi, meaning its only 2 psi off. Very good for the price, and its got a gauge.

[crzycav86]

why do you need a fpr?

[SilviaSlydSydway]

Yeah i have a walbro 255, but dont i need a specific ratio?? like 4:1 or 7:1 or something? And i think i need it cuz i have 370cc injectors. Thanks alot, cuz i know basically nothing about fuel pressure regulators.

[Bosrudorfer]

I have the Nismo FPR with adapter. Costs around $125 or so, I bought mine here on the classifields for $100 shipped.

ONLY get one if you are going to have it dyno tuned by a shop or something.

[Jookmasta]

running a SARD fpr and have had no issues with it. got it from rare trick..............

[KATwo40]

Yeah i have a walbro 255, but dont i need a specific ratio?? like 4:1 or 7:1 or something? And i think i need it cuz i have 370cc injectors. Thanks alot, cuz i know basically nothing about fuel pressure regulators.

You're thinking of the FMU (fuel management unit), which is a regulator that spikes the fuel pressure according to boost pressure, higher than the stock fuel pressure regulator is designed to do.

If you plan on running an SAFC (or other fuel management device), you do not need the FMU.

The stock FPR is at a 1:1 ratio, which is good. This maintains the same delta P across the fuel injector, making for simple fuel tuning.

Hope that helps.

[C-Kwik]

I agree with KATwo40. FMU can also be called Rising Rate Fuel Pressure Regulator (RRFPR). You would want to run thone of these with the stock injectors. You will run extremely rich with 370's installed.

[SilviaSlydSydway]

alright, thanks alot guys. I am just going to get a SAFC and wait for coilovers. Anyone know of a good base map for the safc i can use until i get it tuned? I have an AirResearch T04 Turbo on a Revhard Manifold, 370's and a walbro, a huge intercooler and 2 1/2in. piping. Lets say 7 or 8 psi

[KATwo40]

You need to at least get a wideband O2 sensor (maybe borrow one, or get on the dyno) and tune it correctly. I'd say you could safely begin with -25% correction across the board, both high and low throttle. But I wouldn't park it there and just go boosting away.

[SilviaSlydSydway]

Yeah i just want to get a good base until i can tune it with a wideband. I will probably borrow one unless i find a good place to tune it in South Jersey. Thanks

[KATwo40]

Fly me up, I'll tune it for free. I have an LM-1 with datalogging stuffs.

[tiger]

You need to at least get a wideband O2 sensor (maybe borrow one, or get on the dyno) and tune it correctly. I'd say you could safely begin with -25% correction across the board, both high and low throttle. But I wouldn't park it there and just go boosting away.

I just rebuilt my SR but I really am considering turbo'ing the KA that is running nicely in my 240 right now... I have everything but a manifold and oil line kit. My AFC is the old school one by APEXi... the S-AFC.. I see what you are talking about.. it has all of the RPM ranges with dials... -30 all the way to +30 on each dial.. so if I put this on my KA.. you are saying that I should keep it around -25% from 800rpm to 7200rpm? BTW.. i'm going to be using an HKS 255lph pump and SR injectors.

[KATwo40]

I used to have the old knob-style SAFC and I can tell you now, you should toss it. Just sell it on Ebay and purchase the current SAFC, even if it's not the SAFC2. The tuning points on the new unit are closer (in RPM reference) and the new unit has high and low throttle correction scales, whereas the old unit like yours does not.

Please, do not cheap out on the tuning end of your project. It's the single most important piece in the whole deal.

[partymonster 975]

if u need one, Nismo FPR ftw

[tiger]

So.... if I got a FPR, would that do for the time being.. under regular .7 kpa's (stock sr boost) for the KA? I had the AFC wired into my SR ecu harness...all it really does is just trick the ecu into changing voltage right? I don't know if I want to spend all that money on a new AFC..they are expensive..!

[KATwo40]

No. The FPR only handles fuel pressure, not specific enrichment for specific operation parameters. You could probably use the FMU I discussed above for 7psi on the KA, but I wouldn't push it much past that.