With these mod is it necessary to get a fuel pressure regulator and wire my fuel pump to 12V's?...

i've wondered this question for a few months now....

thanx!...


Mods:

- S4 Block with S5 Externals
- 3" Racing Beat Turbo-Back Exhaust
- S5 Polished Turbo With Massive Ported Wastegate ( Need Install )
- Blitz DD BOV
- Coilovers ( Tein rear, Ground Control front )
- Centerforce Dual-Friction clutch
- HKS PFC F-Con
- HKS GCC
- Knights Turbo-Timer
- Knights FCD
- FD Flywheel
- Racing Beat Swaybar Kit ( Need Install )
- JDM Brake Balancer
- Stainless-Steel Braded Brake Lines
- Autometer boost and A/F guages
- MazdaSpeed steering wheel
- MazdaSpeed racing pedels
- Manaray 6spoke 16" rims
- K&N Filter on 3Inch TID
- Yokohama AVS ES100 Z-Rated rubber
- Greddy ProfecB SpecII Boost controller
- Walbro 255lph Fuel Pump
- Full Custom Grounding Kit
- Greddy Vspec FMIC
- MSD 8.5cm Race-Wires
- Megan Front Strut-Tower Bar
- Megan Rear Strut-Tower Bar ( Need Install )
- Denso 720cc Secondary's

 

any time u turn the boost up or upgrade the injectors its a must to upgrade your fuel system.

 

i have injectors, a walbro 255lph and an FCON with GCC....

do i need the fuel pressure regulator and to wire my fuel pump to 12V constantly?...

thats all i'm asking....

 

Change out the fpr with an aftermarket one as far as changing it to 12v I couldn't tell ya. All I can say is I have much heavier mods than that with an aftermarket FPR and I never changed any voltage.

 

thats really good to know, thanx!...

what should i set the fuel pressure regulator too?...

 

You don't need to rewire the pump for constant 12V. The system puts full voltage to the pump when it's needed (high load), so doing this will only increase fuelling at low load when it's not needed. All you'll do in increase average fuel consumption. It won't be any safer, just a bit thirstier.

 

haha, your always to the rescue!, thanx dude!...

 

i was gunna ask, what are your thoughts on an aftermarket fuel pressure regulator?...

 

Pressure varies by vehicle. I installed a fuel pressure gauge in the engine bay and tuned it till I got a good idle while the car was running. But you need to be careful not to set it too high in fear of going over the max duty cycle on the injectors. I am sure there are other ways but it's really a question of tuning and monitoring your air/fuel throughout the powerband. I really can't remember what the idle fuel pressure was on my TII only because I have it apart at the moment. I think it was around 47psi at idle.. I have large ports and a large turbo. Again not entirely sure.

 

ahh, so it's best suited to be monitored and installed on a dyno....

 

but the stock dual step fuel pump relay isn't the most reliable system.

 

Only re-wire the pump if you're not getting proper voltage...

temp. wire up a multimeter to the pump and check voltage at idle and then under load...if you're not getting prpoer voltage (sorry dunno what the idle voltage would be) then do the mod, other wise if the factory system is still holding up - then don't fix what isn't broke right?

Good luck!

 

IMO most people upgrade them well before it's really necessary. Remember that because it's downstream of the injectors, it can never limit the amount if fuel to the engine by being too small. When it's too small, pressure and flow go up, not down. It's a bit like an undersized wastegate. Instead of a constant fuel pressure differential you get fuel pressure "creep". Aftermarket FPR's generally flow more than stock so they can maintain a consistent fuel pressure differential.

The other benefit of aftermarket FPR's is their adjustability. If you put a bigger pump in the pressure will go up and may cause over-rich mixtures at low load. An adjustable FPR lets lower the pressure back to stock. Alternatively you set the pressure higher if you want. Stock static fuel pressure is ~36psi, and bumping this up to say 40psi will effectively increase the injectors' capacity by ~5%. Increasing it to 45psi will increase it by ~12%. Note that if you're increasing the fuel pressure over stock you have to have a fuel controller or standalone or you'll just end up with rich mixtures, higher fuel consumption and less power.

WTF?! Fuel pressure has nothing to do with injector duty cycle. They are totally independent of one another. In fact the higher the pressure is the lower the injector pulsewidths (and hence duty cycle) required to get the right mixture, so your thinking is completely backwards anyway.

BS. It's a very simple system that rarely fails, and even if it did you'd just get full voltage all the time.

Actually I'd recommend the full rewire (which keeps the two-speed function working) for any modded Turbo. This is especially true if you've upgraded to a Walbro or similar, as they draw a lot more current than the stock pump.

 

that was a good read and i did learn a bit, i DO have a walbro 255lph, so you suggest wiring the pump to 12V's is what i make of it all?...

 

Not constant 12V, no. Follow the procedure for relocating the relay/resistor so you significantly reduce voltage drop between the battery and pump and keep the 2-speed system operational.

http://www.1300cc.com/howto/how2/rewire.htm

It's not as hard as it looks. Let me know if you need and help with it.

 

Interesting.. learn something new everyday.

 

NZconvertible is my freakin' hero....