DIY E89 Z4 fuel system - DI only LPFP / HPFP

fmorelli

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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:
  • 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.
I have been working on these pieces, and far enough along to start posting some information. In the next post, I'll start with the easiest part - upgrading the Z4 to the Walbro 295 pump.

PXL_20210725_230544485.jpg
 
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fmorelli

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So we need to do this on the coffee table in the family room to be sure we get the expected results?
Hahaha ... well it was the closest clean horizontal sunlit surface I had when I came up from the downstairs shop. The Greene brothers might give us a nod, though.
 

fmorelli

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A bit of comparison data on the 295 pump (which some call the 535 since it is rated for 535lph)...

Screen Shot 2021-07-26 at 10.27.58 PM.png


Screen Shot 2021-07-26 at 10.28.19 PM.png
 
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martymil

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The 450 is pointless and a complete waste of time as it overheats the ekp2 to the point where they fail anyway.

One needs to get a ekp3 and a 295 and it will supply all your fuel demands up to around 700hp di only along side the PFS pod.

If one wants to go further might want to consider the f or g series platform, everything from here on gets stupid expensive.
 
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Krampus

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I also installed 295 LPFP and upgraded the fuel line. I ruined the hose connected to the fuel pump and replaced it with a new non-grooved ethanol resistant hose. The original hose was too tight in the pump and hardened. The car cranks a little longer with the 295 pump if you don’t immediately press the start when the door is opened, but it doesn’t matter. HPFP filter is also removed. Flex fuel hardware and inline filter are also istalled. Z4 fuel pump istallation is not fun.
20210707_203120.jpg
I'am using PI but perhaps some day PFS POD.


20210709_175025.jpg
 
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fmorelli

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Filippo, how many miles do you have running the PFS POD? I thought the jury was still out?

I have been working on these pieces, and far enough along to start posting some information. In the next post, I'll start with the easiest part - upgrading the Z4 to the Walbro 295 pump.

Zero miles on anything. I'm in the middle of putting stuff together. I expect to have everything installed in the next month or so. There are some things I need to test along the way, though. I have done several EKP's, but the one I want to run is in the middle of hot air rework. I'll post more in the next few days.

I'm not sure what the definition of the jury being in is? Any suggestions on that?
 
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Jeffman

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I'm not sure what the definition of the jury being in is? Any suggestions on that?
Personally, I’ve put so much time, money, blood, sweat and tears in my car this year that I’m now a lot more risk-averse to any mod that has the potential of seriously damaging the engine. I’d like to see the statistics to date, I.e., number of installs, number of miles driven, number of failures, types of failures, etc.
I’m not expecting a perfect record, but at least I’d like to see numbers that would assure me that it would be very unlikely to have a cracked vacuum plate, broken vacuum pump, killed engine, etc. arising from the PFS POD. Would we need 12-18 months of user date? Maybe.
 
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fmorelli

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Personally, I’ve put so much time, money, blood, sweat and tears in my car this year that I’m now a lot more risk-averse to any mod that has the potential of seriously damaging the engine. I’d like to see the statistics to date, I.e., number of installs, number of miles driven, number of failures, types of failures, etc.
I’m not expecting a perfect record, but at least I’d like to see numbers that would assure me that it would be very unlikely to have a cracked vacuum plate, broken vacuum pump, killed engine, etc. arising from the PFS POD. Would we need 12-18 months of user date? Maybe.
I agree with this - and it is very well said.

I had a lot of dialog before making the decision, and I agree there is risk (your list of what you'd like to see explains that). I have about $10k+ worth of parts, 2 years in the making, waiting to go onto the car, and needing fuel. I really did not want to go PI (nothing wrong with it, but not the approach I want to take). So either I went PI, or I went with this. IMHO, I think the POD is in a better place than what I've seen with the Helix. That's a personal opinion on my own research, and why I went this way. But I agree ... 12-18 months out would be great ... I don't want to wait yet another year ... so yeah I'm an early adopter ... wish me luck! :)
 

fmorelli

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The Walbro "535" LPFP build
I bought the Walbro pump and install kit as one unit from JDT Racing.

Building the 535lph-capable Z4 LPFP is fairly straightforward. Installation is a different animal, which I'll cover in a later post. I recommend buying a used factory Z4 fuel bucket. This will set you back about $100, but convenient to swap. If one doesn't wish to spend the $100, the good news is that the conversion is quick so downtime is minimum.

When the bucket comes apart, you will destroy two hoses - the 315mm primary hose from the pump to the outlet on the regulator/filter side, and the short return line that comes from the T back into the fuel bucket. The 125m short line needs to be cut to be able to disassemble the fuel bucket. Cut the short line in half so the bucket can come apart.

Z4 lpfp plumbing.jpg short line.jpg

The bucket has two tabs the hold the inner sleeve (which holds the pump assembly) in the outer bucket. Two small flat screwdrivers can be slid into the tabs and left there. Simply pull the inner sleeve out. Now the pump is visible. Just pull off the filter, and pop the pump out of the inner sleeve. Using a box cutting razor blade, carefully cut the two lines at the barb ends for the main line from the pump to the connector, and the earlier 125mm line that was cut, so that the lines can be slipped off the barbs.

Next, I recommend reusing the factory sock filter. Clean the sock liberally with brake cleaner. I had a bit of debri on the bottom which quickly came clean (which can be seen in the photo below).

sock filter.jpg

The new pump is a direct fit, both to the factory sock filter and the inner bucket sleeve. What is different? The Walbro 295 pump has an integrated wiring harness, where as the factory pump has a brown and black wire which are simply clipped on. Unclip the wires from the factory pump. Cut the two crimp connectors off. The Walbro 400-1168 kit includes the connectors which are to be installed on the factory harness, where the original fuel pump clips were cut. As for wiring - red wire from Walbro is positive, white is ground. Wire the connector so white/brown and red/black. Once the Walbro connector is assembled onto the factory harness, it can plug directly into the pump connector. Below one can see the parts needed and the resulting wiring assembly.

vpn-400-1168_xl.jpg harness.jpg

The two replacement hoses and clamps will come from the kit I note above, and the 300mm line noted above. As I mention in the above photo, one can use the supplied clamps, but I prefer using Oetiker style clamps for everything. If going that route, one can purchase a oetiker clamp kit. To install the two lines, you'll need oetiker clamp tool. I highly recommend the Knipex 10 99 I220.

Two small points on the replacement - the 300mm replacement line is of sufficient length for replacing the factory 300mm line. The 100mm line is actually replaced with a slightly longer line (from the Walbro 400-1168 kit) which provides enough length that one can actually now disassemble the bucket without cutting the short T line.

At this point one has a completely functional Walbro 295 pump. Remember it has no check valve. On the Z4 one can run without a check valve. Alternately, an inline Fuelab filter with check valve can be used underneath the car. Specifically the Fuelab 84831, which supports ethanol, and provides 6 micron filtration which lets one remove the filter in the HPFP.

disassembled.jpg



PXL_20210725_230544485.jpg
 

sjobusen

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Following.... Just ordered the Walbro 295 from summit racing. And have a used z4 lpfp bucket ready for doing the swap.
Do I need to do anything with my ekpm?
I have a 2010 Z4 35i from Europe.
 

fmorelli

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Interesting didn't know about the voltage fix. @martymil has been running the 295 with an ekpm3 without issue. I'm working on an EKPM3 with an updated half bridge IC (where the amperage draw goes through) and a higher efficiency heat transfer thermal pad ... just for added headroom.

I haven't written up the EKP upgrade yet, as I've not gotten my EKP running ... my hot air rework might not have been good enough. Will post up info with all details once I have a working unit.
 

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ShocknAwe

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I made the 535/295 pump upgrade jump with a full PR built bucket a while back too after seeing the results posted in the comparison thread and talking with Marty. Previously had a 450 and the 535 definitely outclasses it.

Stock EKPM3 and recently took the plunge on the BPM4 unit to futureproof the EKP. Also upgrading the LPFP sensor and fuel line to the new part numbers when that gets here.

So once that's done all that will be left is the DI solution. I'm 93 octane only on my build so I don't know if I really NEED the POD. For now I'm on the side of, not yet, and will patiently watch the results of their product adoptionby the likes of Filippo and other members.
 
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