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

[proboner]

But drilling doesn't do anything, there is even a bigger restriction you might want to take care off, the lpfp sensor line but that requires a bit of fab work. If you leave it stock keep an eye on your lpfp pressures and get rid of the factory hpfp filter as that can cause starvation issues to your hpfp pump even though you have full lpfp pressure and cause premature failure of the pump.

I mean, I dont know what to say if drilling the rail doesn't do anything but my rail pressure is 900psi after drilling out the inlet. That said, it has come down on subsequent runs.

Either way, I'm just doing things in stages to see what kind of gains I get from each. The plan is to upgrade each component as the need arises. Starting with drilling out the fuel rail, line from the HPFP to the ethanol content sensor, then finally removing the HPFP filter and replacing the entire line back to the pump (with an inline filter). I can't see how the lpfp hardline is a bigger restriction than that sub 1/16" fuel rail inlet, though. I mean I get that we're working with different pressures, but how does that math work out?

Why is the fuel rail itself so restrictive? Line from HPFP to rail, lines from rail to injectors, injector inlets, all HUGE by comparison to the fuel rail itself. Does the rail do any amount of metering? Is the rail what the HPFP pushes against to build such high pressures? It jus seems weird.

 

[martymil]

I was joking of course the fuel inlet is a restriction, people bagged this mod which vtt came up with and I found more and got
hammered for it by certain parties on this website. Glad you found the extra pressure just dont let the hpfp starve on the lpfp side.

 

[proboner]

I was joking of course the fuel inlet is a restriction, people bagged this mod which vtt came up with and I found more and got
hammered for it by certain parties on this website. Glad you found the extra pressure just dont let the hpfp starve on the lpfp side.

Have a stage 2 pump currently and wired in an LPF sensor recently, so definitely keeping track. I can't help but wonder if there's more advantage to be had by opening up the rail inlet and injector outlets even more? Has anyone ever seen a downside?

 

[martymil]

no there is not as I done it and there is no need to do it as there was no benefit.

But what you will see is an increase in fluctuations on the lpfp and hpfp as the smaller holes act like little buffers.

 

[SLOWESTN54]

PFS need to start selling their upgraded rail separately from the overdrive kit. I think it would be a hit

 

[Torgus]

PFS need to start selling their upgraded rail separately from the overdrive kit. I think it would be a hit

What is special about their rail?

 

[SLOWESTN54]

What is special about their rail?

I’ll take pictures next time I have the hood up. It’s Center fed instead of the traditional inlet on the front. Seems to have bigger internal ports. Most importantly it looks cool

 

[proboner]

Someone hasn't done their reading lol

Speedflow 171-06-14

M14 x 1.5

Curious if you actually run this? I'm mocking this all up right now and am getting leakage from this part. The stock system has conical internal seal and with this M14x1.5 fitting that seal is no longer there. Is thread tape enough? Just tighten it down super tight? Thoughts?

 

[martymil]

Answered about the wrong fitting previously, deleted the answer.

This is the fitting for the hpfp your using ?

These fittings are weak and can easily crack which most likely happen if you overtighten them.

I started making my own for the HPFP as for this exact reason.

Cut of the end of tha factory LPFP stainless line and weld on a steel dash 6 weldon to use as an adapter.

 

[proboner]

Answered about the wrong fitting previously, deleted the answer.

This is the fitting for the hpfp your using ?

These fittings are weak and can easily crack which most likely happen if you overtighten them.

I started making my own for the HPFP as for this exact reason.

Cut of the end of tha factory LPFP stainless line and weld on a steel dash 6 weldon to use as an adapter.

So what's the benefit of replacing the hardline? I've heard a lot about the bends in the line being super restrictive, but I cut them apart and measured and they're not much different from the straight sections?

Hardline to HPFP inlet ID: ~5.5mm
Hardline to HPFP outlet ID: ~6mm
Hardline to HPFP bend ID: ~7mm x 5mm

 

[martymil]

So what's the benefit of replacing the hardline? I've heard a lot about the bends in the line being super restrictive, but I cut them apart and measured and they're not much different from the straight sections?

Hardline to HPFP inlet ID: ~5.5mm
Hardline to HPFP outlet ID: ~6mm
Hardline to HPFP bend ID: ~7mm x 5mm

I've seen plenty down to 1 to 2mm on the bends before the sensor and posted about it showing the restrictions, still I would cut the line
between the hpfp and the lpfp sensor and weld on a dash 6 steel connection and relocate the lpfp sensor as far away from the hpfp as possible.

Or mount it on the reference point of the external regulator to minimise the lpfp pressure spikes as the sensor is way to sensitive.

 

[proboner]

I've seen plenty down to 1 to 2mm on the bends before the sensor and posted about it showing the restrictions, still I would cut the line
between the hpfp and the lpfp sensor and weld on a dash 6 steel connection and relocate the lpfp sensor as far away from the hpfp as possible.

Or mount it on the reference point of the external regulator to minimise the lpfp pressure spikes as the sensor is way to sensitive.

As I'm building this entire aftermarket tank to HPFP setup I'm frankly seeing less and less of a benefit. The only benefits that seem obvious at this point are removing the HPFP filter, which obviously requires a filter inline somewhere, and drilling out the fuel rail. All the lines from the tank to the HPFP seem pretty consistently sized and certainly not any smaller than the outlet at the fuel hat, which is the main irreplaceable restriction anyways.

 

[martymil]

The problem is not just the line but also the location of the lpfp sensor, any restriction is one even if it necks down 1 or 2mm.

Ovaling of the pipes will slow flow especially at high rpm where fuel supply is critical and many have seen a 200 to 300psi lift on the hpfp removing these where the hpfp is on its ragged edge.

 

[KClemente]

@martymil I think i’m gonna go with your recommendation to weld a fitting on my stock line. Is -6 not too big? And do you have a preference of which fittings size up nicely with the stock lines? Pre hpfp and post hpfp lines.

 

[martymil]

Any steel fitting will weld up nicely.

 

[CantSitStill]

Hi. Thought i would chime in with my results from the fuel filter/rail mod. Im doing this on pump gas which i could not really find any example of. I was getting rail drain to about 1000psi if i hit about 22psi to the red line, it was crashing fast, so fast it would limp mode with missfires. At 21psi it was right on the edge and 20psi i could just hold over 1500psi to the red line on pump 93. 19T turbos. Dyna pack @ 500whp (probably about 450 on other dyno's).

Anyway forget 400-500psi more. In my example, it gained 1000psi which is nuts. All i did was installed a standard fuel hose from the tank (using a new quick-connect fitting clamped to the hose) to a bosch filter mounted on the small rack next to the HPFP using a hose barb - https://trackformula.co.uk/product/bosch-8-micron-performance-fuel-filter/. I then cut the rubber hose to the HPFP and clamped it on another hose barb on the other side of the filter. Then i removed the HPFP filter which was already very clean. I drilled the rail with a 2mm drill bit. Prob cost me 60-70 quid.

BEFORE

https://datazap.me/u/stuie1982/v15?log=0&data=3-13-17-20-21&mark=48

6700rpm, 19.7 psi, 1650psi rail, 79f IAT, 161 load

AFTER

https://datazap.me/u/stuie1982/v10-wedge-after-hpfp-mod?log=1&data=3-13-16-20-21&mark=42

6700 rpm, 19.6 psi, 2700psi rail, 75f IAT, 161 load

My rail is not dropping below 2200 psi now anywhere, makes me wonder how much more boost I could run!! I have read so mixed reviews about this mod not making a big difference, or none at all so wanted to try and post a pump before and after

 

[martymil]

Hi. Thought i would chime in with my results from the fuel filter/rail mod. Im doing this on pump gas which i could not really find any example of. I was getting rail drain to about 1000psi if i hit about 22psi to the red line, it was crashing fast, so fast it would limp mode with missfires. At 21psi it was right on the edge and 20psi i could just hold over 1500psi to the red line on pump 93. 19T turbos. Dyna pack @ 500whp (probably about 450 on other dyno's).

Anyway forget 400-500psi more. In my example, it gained 1000psi which is nuts. All i did was installed a standard fuel hose from the tank (using a new quick-connect fitting clamped to the hose) to a bosch filter mounted on the small rack next to the HPFP using a hose barb - https://trackformula.co.uk/product/bosch-8-micron-performance-fuel-filter/. I then cut the rubber hose to the HPFP and clamped it on another hose barb on the other side of the filter. Then i removed the HPFP filter which was already very clean. I drilled the rail with a 2mm drill bit. Prob cost me 60-70 quid.

BEFORE

https://datazap.me/u/stuie1982/v15?log=0&data=3-13-17-20-21&mark=48

6700rpm, 19.7 psi, 1650psi rail, 79f IAT, 161 load

AFTER

https://datazap.me/u/stuie1982/v10-wedge-after-hpfp-mod?log=1&data=3-13-16-20-21&mark=42

6700 rpm, 19.6 psi, 2700psi rail, 75f IAT, 161 load

My rail is not dropping below 2200 psi now anywhere, makes me wonder how much more boost I could run!! I have read so mixed reviews about this mod not making a big difference, or none at all so wanted to try and post a pump before and after

I posted about these issues and fixes with same results years ago, the problem is fourms get so messy and posts get burried, great to hear people are still finding this info and use it to solve the fueling issues.

Great result.

 

[CantSitStill]

It was your info that made me do it so thanks dude. I almost never did the rail drill because I was worried about a burr coming off inside but I ended up forgetting to close off one of the injectors and from inside activated the pump via ista which does it for 20 secs with no way to cancel it. Never seen so much fuel be sprayed all over the place. Hit my partners car parked 1 meter away. Longest 20 secs of my life. If there was a burr it's out now!

 

[martymil]

Another thing is you might not want to run anymore than 20 to 21 psi on a stock block as they are the weakest link in the whole equation.

Some have ran more and been fine but a lot have cracked the cylinder liners including myself eventually after extended use but as long as your fine of taking the risk you could turn it up another 1 or 2 psi judging from the logs, but what I found things go pretty badly quickly at anything over 21psi and seen many broken n54's at those levels and hope you got the funds to build or get another motor.

Happy boosting.

 

[martymil]

Also for others when you drill the rail remove it from the car and take the hpfp sensor out and after drilling blow it out with compressed air.

Whilst drilling apply a bit of drill and cutting compound it doesn't let the metal break off and go flying everywhere inside the rail, it comes out like a spiral and in one piece.

It just makes things a lot easier and safer.

Hope this info helps in the future.