View Full Version : 255lph Walbro and AFPR enough?

04-08-2006, 12:31 AM
Hello! I need help tuning the fuel in my 94 Phantom. Remember I asked about the SRT-4 255lph Walbro? well, Im going to find out tomorrow morning if it fits.

My set up is: mexican 2.5 T2, Garrett (no more mitsu), A-413 with oil cooler, SRT IC, AFPR, Walbro 255lph, timing at 9, Fidanza adjustable cam sprocket, no balance shafts, UDP, MAP clamp, Greddy Profec B for boost control.

Before the Garrett, the car had a mitsu turbo at 15psi, timing was at 12, the AFPR was set at 50psi with the vacuum disconected. Now with the Garrett, the fuel is set to 55psi with vacuum disconected. The car is a lot faster with the Garrett at the same boost but Im not sure 15psi with the Garrett is enough to reach my goal with this car, Im aiming for a mid 13 second pass.

My questions are:
How much boost do you thing Ill need for a 13.5 at 7000ft of altitude?
Will the 255 Walbro, AFPR and stock 33pph injectors be enough for the needed boost?
Do I need much lower base pressure with the Walbro?
Do I need a RRR?

With the Mitsu and 15psi I could only net a couple of 14.80 ets.

Now with the Garret while playing with the profec I accidentally upped the boost to 23psi, the car was a blast, and to my surprise the air/fuel gauge read rich, very rich. I have a Nordskog digital gauge that reads in numbers, on the 23psi run the gauge went to 1.2v. After the very short blast I checked the plugs and saw no signs of detonation. I know that a wideband monitor will be better for tuning, but the plugs clearly show a rich condition. This seems strange with that much boost dont you think? Im thinking maybe it has to do with the very high altitude (7000ft) and the lack of oxygen? If there is less oxygen less fuel is needed right?.

I dont want to run the car at the track yet, I want every thing to be in order, that is why Im asking you guys :).

04-09-2006, 10:09 AM
Get a wide band o2 sensor. Stock one doesn't tell you much.

You definately want +20 or +40 injectors. Stock one only good for about 15psi until the melt your piston, especial in a 2.5L. It needs more fuel.