[ZL1...SON]

Originally Posted by MartinLe

OK, in a perfect world, we have 75# low side and 2900# at the rail and IPW's in the mid 5's. Of the three numbers, the IPW's are the most important in keeping the motor in one piece. Now we have some fluctuation in the fuel pressure, but the IPW's stay in the happy zone. During a run, the low side hangs in there at 70#+ and IPW's are in the low 5's. At the shift into second at 7K, in that little window of rpm drop at the disengagement of the clutch, the rail pressure drops to 2000# (low side 70#) and the IPW's raise to 5.8 - 5.9 for a split second, and then rail goes up to 2800# and IPW's back to mid 5's. The motor is happy. This is my understanding.

When I installed the blower/cam package, I was discouraged from the LPE BB pump because it ran at 2175#. "We want to have the 2900# at the rail at all times." You are running a steady 2175# at the rail and the IPW's are in the 5's. How can that be argued as anything less than safe and acceptable? Some tuners will argue the 2175#. But the IPW's are in the happy zone.

As Josh stated, the higher the pressure the lower the volume. The LPE pump will run under some conditions at 2900#, but it is designed for 2175#. Why wouldn't the OEM pump push more fuel at a lower PSI?

I apologize if this is a little derail of the OP's intent, but it is about pressures.

I know this is an older thread, but wanting to bring this back up as I am currently getting my car dialed in after the addition of the Jokerz race port, XDI +30s and LPE BB HPFP. I ran into the rail getting drained and injector PWs going through the roof as described in this thread. I am currently doing a lot of research on this and working with my tuner to see where we can safely get the ethanol content up to. I brought up the possibility for dropping the rail pressure down from 2,900, as discussed in this thread.

Soooo... megahertz, I would definitely be interested in more conversation on this topic and anything that you and KingLT1 have learned since the last conversations here.

Another question I have is about the Scaler Offset, and Gain for these pumps. I have read where in the past these needed to be changed to 12.5 and 8.75... but is that still accurate for the pumps today? What happens if those don't get changed? Mine have not been changed and other than running out of fuel at 60% E, the car has run great after the parts were added and tuned on 93.