DIY : PTFE line- tank to HPFP + inline fuel filter upgrade

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Nov 5, 2016
116
SC
#1
Inspired by martymil’s post I decided to pull my HPFP filter, drill my fuel rail, add an inline filter and upgrade the line from the tank to the HPFP hard line. There are some gains by going straight to the HPFP but people are using a 1/8 npt adapter and the LPFP seals with an o-ring. Everyone says it works, but I decided to just leave the stock hard line. I was not a huge fan of pushloc hose so I looked into PTFE hose. It is much better suited for ethanol. The downside is that generally it is less flexible when compared to rubber hose. It was a tight fit especially for the fuel filter but overall turned out well. I chose to go with Racetronix hose and fittings because they offer quick connect PTFE hose ends. It makes for a clean install. This is a great option if you are just looking to upgrade the line from the tank to the HPFP or are looking to upgrade the line and add an ethanol sensor. Obviously the inline filter is optional when pulling the HPFP filter but I figure it is extra insurance. I do not have results yet due to breaking in a new clutch but will post up logs when I can. Based on martmils and others results it should help a bit on the high pressure side.

Parts list if adding an inline filter (If using an ethanol sensor you will need 2 additional $10 fittings) 7 feet will most likely work but 8 is a safer bet.

Fuel filter element- This was the smallest micron filter I was able to find that was rated for ethanol.

Parts list if just upgrading the line and adding an ethanol sensor- (remove the 2 6an-3/8 quick connect if just looking to upgrade the line)
Drilled fuel rail (11/64 or 3/16 drill bit) Before/After

HPFP filter removed

Mounting the fuel filter (note: this is on a manual trans car. The clutch line had to be slightly bent) Dimensions just to give a rough idea and your results may be different.

Upper line from filter to hard line (90 6an end to 6an 5/16 female quick connect). You will want to remove the intake manifold for easier access to the quick disconnect on the hard line.

Modified stock clips- I use a Dremel to modify the stock clips so the new line clips into place. The two rear clips have a larger spot that is not used so the rear two do not need to be modified.

This stock bracket needs to be bent to give a little extra clearance for the new fuel line. It can easily be bent back to stock

Rear hose/house routing. It runs pretty much in the location of the stock line and does not rub anywhere. It is a tight fit routing it up to the tank. It helps to remove the drive side tank strap bolt for more clearance. I did not measure the exact length on this hose as your results will vary depending on filter mounting.
 
Jun 4, 2017
795
#4
Thank you! You are correct. Sorry about that. I had the album set as private so when I was logged in all the pictures were there. They should be visible now.
All visible now. Nice work! I love seeing others do clean custom install work. So many people out there hack everything.
 
Sep 6, 2017
468
Down Under
#7
Dude I'm glad you made your own, looks great.

From what I've seen it picks up about 400 to 500 psi on the hpfp when the pump is struggling on the stock lines.

It just gives a little extra headroom to play with.
 

doublespaces

Administrator
Oct 18, 2016
6,681
AZ
#8
Why did you decide to keep the hardline? And does this inline filter restrict less, because the filter is larger?
 
Sep 6, 2017
468
Down Under
#9
The biggest restriction is the filter in the hpfp pump, the hard line is another 150 psi or so

The inline filter will flow at least 10x more and stay cleaner longer.
 

Twisted Tuning

Lieutenant
Platinum Vendor
Oct 25, 2016
747
New York
#11
Good job. glad more people are seemingly starting to utilize more outside the box thinking and doing more themselves.
 

PRECISION RACEWORKS

Corporal
Platinum Vendor
Nov 11, 2016
137
HOUSTON TX
#13
This is interesting "Idea" but personally don't recommend it... The HPFP is the weak link not the screen in the line it is just another fail safe to protect injectors. You still left the biggest restriction in the entire fuel system which is the in tank filter assembly.

I like the outside the box thinking but it's always important to do testing and make sure these mods yield results. Your install looks very clean and well thought out though I'll give you that for sure good work!
 

BQTuning

Corporal
Free Vendor
Jul 18, 2017
163
#15
This fuel rail keeps coming back to me. Why is it that BMW used the fuel rail from the N53 on the 135i and 1M N54 cars which is a different part number from the fuel rail thats on all other N54 3, 5, 7 series, X6, and Z4 cars ?

Logically since the 1M is rated the most powerful N54 car using the N53 fuel rail, would this be suggesting the N53 fuel rail part number has better flow ? I cant fine any physical differences between the two part numbers from a picture view.
 
Nov 5, 2016
116
SC
#16
All visible now. Nice work! I love seeing others do clean custom install work. So many people out there hack everything.
Thanks I appreciate that! I agree you see hack jobs more often than not.

How much extra margin does this give you with the HPFP?
I am still breaking in my clutch but I expect between 300-500. If I remember martymil gained about 500. A local pulled his filter and drilled his rail and gained around 300. I will say his pump was not struggling as much as mine so I am curious to see the results. I will post logs when I get done

Dude I'm glad you made your own, looks great.

From what I've seen it picks up about 400 to 500 psi on the hpfp when the pump is struggling on the stock lines.

It just gives a little extra headroom to play with.
Thank you for your write up!!

Why did you decide to keep the hardline? And does this inline filter restrict less, because the filter is larger?
The fitting most use has a 1/8 npt port. The stock LP fuel sensor seals with an o-ring so I was not comfortable using a NPT fitting for that. On the flip side multiple people have used it with no issues. I may address that down the road. Ill see where this takes me first.

Good job. glad more people are seemingly starting to utilize more outside the box thinking and doing more themselves.
Thank you. Do you still plan on a n54 hpfp upgrade?

This is interesting "Idea" but personally don't recommend it... The HPFP is the weak link not the screen in the line it is just another fail safe to protect injectors. You still left the biggest restriction in the entire fuel system which is the in tank filter assembly.


I like the outside the box thinking but it's always important to do testing and make sure these mods yield results. Your install looks very clean and well thought out though I'll give you that for sure good work!
Thank you, but I am definitely not the first to pull the filter and drill the rail. It should help 300-500psi on the high side. Is it a huge change? No, but any gain on the high side is good with me. I agree the HPFP is is weak link but seeing as there is no solid HPFP upgrade this is why I chose to do this. I am not a fan of port injection and would like to stay DI only. I get the filter being a fail safe that is why I chose to add a larger inline filter. I imagine some of the gains from the filter becoming dirty. As for the tank filter assembly I know y'all and a few people in the past have developed one but I haven't seen results. This is definitely not the upgrade for someone looking for huge power. I am hoping to get around 550ish on an ethanol mix.
 
Last edited:

jyamona

Lieutenant
Free Vendor
Nov 7, 2016
758
Philly
#18
Has anyone seen the hpfp filter look gunked up at all when it is removed?
 

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