Hi folks.

Just fitted my new fuel system

Now running:

Walbro gst400 (400lph pump)
Bosch 1680 Secondaries
Mazda oem 850cc primaries
Sard FPR
Braided Lines etc etc
New Filter and plugs
No Leaks

So in setting thee fpr - what should my base pressure be?

 

~40psi. Really depends on how the 850s let you idle.

 

43.5 PSI is the standard.

 

43.5 psi. You'd get a better idle and smoother transition if you went with the newer style bosch ev14s.

 

The factory pressure is around 35psi iirc, but like everybody else has said, most people run 43.5psi.

I should think it would depend on 2 things.. 1) is your engine happy with the lower base pressure, and 2) how much fuel flow do you need at your max boost settings.

As fuel pressure increases pump flow decreases. So if you're going to be running an *** ton of boost you need to be sure your pump will flow enough fuel to satisfy your engine needs at that level.

 

I run 38 PSI, so does the person I am tuning.

 

factory pressure is 2.5 bar on stock injectors. lots of people switch to 3 bar (43.5 psi) when changing out injectors.

 

Bosch ev14 and ID injectors call for 43.5, which is why it is becoming the norm.

 

I run stock base pressure, IIRC is 38psi. I'm running stock primary and EV14 2000 secondary, didn't know what to set it at since the primary and secondary call for different base pressure.

When I had the car tune, my tuner said the secondaries transition like 1600 instead of 2000, I'm guessing it has something to do with the lower pressure I'm running. My A/F is solid at 11 across the board and max duty cycle I see is ~65%, so I just left the pressure alone.