Having pretty much wrapped up the suspension and brakes on the Z4, my next phase is to upgrade the fuel system. This is precursor work, preparing for the VAC ported head, Schrick cams, Hydra HP650 turbos and clutch.
My plan has always been to be DI only, with a target of 600whp. A bit of history:
I first purchased a VTT single barrel to drive the HPFP. A Fuel-It Walbro 450 was installed in preparation for more fuel. I sold the single barrel before installing it, as I understood there were enough unknowns on the Z4 with that setup that I was not comfortable going that direction. Next, I purchased an M4 S55 dual HPFP and worked on a project with several others here, hoping to adapt the S55 dual HPFP to the N54 with native DME control. That has never come to fruition. (anyone interesting in a 4k mile dual HPFP with modded dual fuel feed N54 rail, PM me!). Then the Helix came out, and I had found my solution, or so I thought. After some time, I became convinced that was not the solution.
A Z4 friend once told me, "If you can't find a solution with your N54, just wait a while." ... so three things happened in the last couple years that made a 600whp reliable DI only system viable with the N54:
My plan has always been to be DI only, with a target of 600whp. A bit of history:
I first purchased a VTT single barrel to drive the HPFP. A Fuel-It Walbro 450 was installed in preparation for more fuel. I sold the single barrel before installing it, as I understood there were enough unknowns on the Z4 with that setup that I was not comfortable going that direction. Next, I purchased an M4 S55 dual HPFP and worked on a project with several others here, hoping to adapt the S55 dual HPFP to the N54 with native DME control. That has never come to fruition. (anyone interesting in a 4k mile dual HPFP with modded dual fuel feed N54 rail, PM me!). Then the Helix came out, and I had found my solution, or so I thought. After some time, I became convinced that was not the solution.
A Z4 friend once told me, "If you can't find a solution with your N54, just wait a while." ... so three things happened in the last couple years that made a 600whp reliable DI only system viable with the N54:
- The Walbro 295 LPFP pump was released - this is basically the E85 Hellcat pump without a check valve. It draws less amperage than the 525 and flows more fuel. As a bonus the Z4 does not run a LPFP sensor, so a check valve is not really needed. (though one can install an fuelab's inline filter with check valve, if a valve is desired).
- Development on the EKP have shown several things. First off the EKPM2 seems better suited for handling heat than the later EKPM3. But there are two other positive notes on the EKPM3. @martymil has been running a Walbro 295 with an EKPM3 without issue. But the second discovery - the half bridge IC in the EKPM3 that takes the brunt of the abuse (it powers the LPFP) ... well, Infineon made an improved version of that half bridge, some time after BMW was making the EKPM3. So one can upgrade that half-bridge, which is more efficient than the original version. Finally it was determined that further heat transference from the EKP can be facilitated by a better quality heat transfer pad, and optionally a heat sink on the bottom of the EKP chassis.
- The final piece of the puzzle, PFS released an HPFP overdrive called the POD, which does not exhibit the vibration issues that the Helix seem to frequently demonstrate.
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