OK, I spoke to Kenji again from Greddy this week, and he strongly recommended a new fuel pump when boosting anything more than 5.5psi. He said during testing, the stock fuel pressure would drop...even at 5psi of boost.

So my question to those that installed the Walbro 255, do I really need a regulator? Kenji said a reg is not necessary.

I am heard conflicting reports of whether we need a regular and/or a return line for optimum results. How will this new fuel pump effect my A/F across the board? Well the stock FPR keep the PSI from spiking...and hence...richening up my mixture? I dont mind a slightly richer curve across the board, since I could always lean it up across the board with the eManage.

 

From what I have been told the Walbro 255 w/o regulator will raise pressure slightly at idle but should mantain pressure thru the rpms. By adding the regulator you get a return line and a boost compensated pressure increase. Will find out tomorrow since I can't find time to install my regulator until next weekend.

MIKE

 

Yeah, keep me posted...I am interesting in seeing how the car runs with just the fuel pump.

 

No it does not affect fuel pressure at all. The stock regulator works just like stock. It simply has the flow necessary to maintain fuel pressure at high RPM's. YOu can change it even on a stock car with no ill effects.

 

since me up! Where can I buy one cheap?

 

how much boost do you plan to run?

 

Call gruppe-s and they will hook you up for $90 including shipping.

 

Without a regulator the pressure jumped from 50 to 58psi and made the car run really rich. Even at WOT it stayed there. that is why I went ahead and installed the regulator. I would guess that with the emanage you could lean it out enough to fix this but because I am run the TS flash I had to install a regulator. The internal regulator can not return enough fuel to compenstate for a walbro 255hp. If you don't want to install a regulator I would buy a walbro 190 or a 255 low pressure pump. that should keep your fuel pressure in check and supply enough fuel for the higher rpm's. Just my .02

 

Good tip spaz in Texas

 

Thats for the info Spaz. If it runs rich, with one click, I can lean the entire map with the eManage. If anyone is interested, you'd just goto "Parameter" and goto the injector scaler and just set the "after" value at greater than 440cc. So maybe like 460 or 470. Essentially, the emanage would think you have slightly bigger injectors than 440cc, and lean out the map slightly more. Then you could confirm the AF with a wideband or dyno run.

 

just to let everyone know that the rc lucus 440cc are rated at 43.5psi. At 58psi they would be 508cc injectors. That is what you would have to enter on the parameter page. found this info on rc's web page. Now if I only knew what the pe injectors are rated at?

 

I will probably take it to 8.5psi for daily-driver purposes, but I'd like the potential to go about that from a fueling perspective.

 

https://my350z.com/forum/forced-induction/70497-ultimate-racing-on-fuel-and-timing.html

Some good info you should be aware of about the fuel pressure regulator on the Z