OEM fuel pump lines and fittings to intank fuel pumps

[EVO-00X]

Well it seems those who rushed out to buy a new Walbro 400lph intank fuel pump are kicking themselves. During April Walbro released the all new E85 Certified 400lph version. But hold onto your money for a bit longer boys. Comparisons are still being made against the current favourite, the Aeromotive Stealth 340lph. The Aeromotive is reported to provide more flow on less amperage between 40-70psi, which is what most of us will be seeing in our fuel pressures anyway. There still needs to be more comparisons before definite conclusions can be made by reputable testors.

In the meantime, has anyone installed either one of these in their GSR/EVO yet? The Walbro 400lph is definitely a bit longer and wider at the base and was wondering if there were any issues?

Also if you do install one, take note that the exit diameter of the Walbro 400lph pump is 5/16" so you would want to make sure that ALL your plumbing from the pump itself to the fuel rail was a minimum of 3/8" hose diameter with 6AN fittings all the way through!! This should still give good enough power for 600hp E85 setups, or you may wish to upgrade to 1/2" and 8AN lines.

For those who might not know yet, the OEM fuel pump power wiring simply WILL NOT provide enough amperage to run these hi powered fuel pumps properly. You will need to change your power supply to the fuel pump via direct power cable from the battery and having your tiny OEM power wire used as the switch on a 30A relay.

Tonight I revisited the stock metal pipe fittings on the outside of our EVO I-III and GSR fuel pump cradles and when you unscrew the metal fitting and look inside it, it certainly does have a massive restriction. But when comparing it to the outlet of the Walbro 255lph they are the exact same size! So even though the OEM hoses and hardlines are supposed to be 5/16" in diameter, the Walbro 255 outlet and hard OEM fittings on the outside of the fuel cradle, plus the end adapters on either side of the OEM fuel rail are still very restrictive. See attached pics.

Therefore when you do want to install a single intank fuel pump larger than a Walbro 255lph, you will NEED to consider modifying the top cover of the intank pump assembly to allow for a 6AN fitting or larger to be installed through it and straight to high flowing intank fuel pumps with 5/16" outlets or bigger.

In the coming weeks Im finally going to get rid of the OEM hard line under my car and replace it with either 3/8" alloy tubing and 6AN connectors, or 1/2" tubing with 8AN connectors from the firewall to the fuel tank. I have already upgraded my engine bay plumbing to 8AN fuel lines and fuel filter etc when I did all the inital engine work, so its just a matter of upsizing the fuel flow from the firewall backwards that needs attention now.
As part of the works I'll be installing a bulkhead into the fuel pump cradle lid too with hose connection to the pump. Cost... maybe not even $200 worth of parts including shipping from Summit Racing. Parts will include the alloy line, some braided lines and anodised fittings and adapters. I'll do a DIY write up with pics and part numbers about it when I get it sorted.

Just take a look at the Walbro 255 outlet and the OEM fuel cradle hard line adapter vs the larger diameter of a 6AN fuel connection. 8AN is even bigger obviously lol...

 

[brisvr4]

Rob,
I just did a quick comparison between the Aeromotive and new E85 Walbro 450 pump between 40psi and 70.
Both sets of figures are based on 13.5v tests.

Walbro 450l E85
40psi - 430l 15.29amps
50psi - 405l 16.07amps
60psi - 381l 16.91amps
70psi - 355l 17.82amps

Aeromotive Stealth 340
40psi - 340l 13.0amps
50psi - 320l 14.2amps
60psi - 280l 15.5amps
70psi - 250l 16.0amps

Please note that the Aeromotive figures are close estimates as I only had a graph to work from but they are pretty close to the mark!
Personally I would upgrade the wiring and run the Walbro for the huge flow difference that it offers over anything in the same size bracket.
As you can see, the Walbro pump gives almost 100l for flow in most of the psi ranges.

 

[lozza]

As part of the works I'll be installing a 6AN bulkhead into the fuel cradle lid too with 3/8" connection to the pump. Cost... maybe not even $200 worth of parts including shipping from Summit Racing. Parts will include the 3/8" alloy line, some braided lines and anodised fittings and adapters. I'll do a DIY write up with pics and part numbers about it when I get it sorted.

I have just upgraded my entire fuel system to -6AN including hard lines under the car. I came across this same size problem. However, with my GSR I just couldn't fit a -6 bulkhead into the lid and still have enough clearance to fit the intank walbro to it - it's just too close to the top of the cradle.
I ended up remaking the cradle lid and placing the bulkheads in it and running an external lift pump (that's another story)

I believe in VR4's there is more head room (can even install double intank) so bulkheads can work, but not in a GSR with std cradle.

Maybe your tank/cradle is different - mine is aussie spec GSR.

 

[ONPSI]

Nothing a few modifcations can't fix. Mick (TRIPPY) has done double pumper 400's intank on a standard Evo IX cradle and also mixed it up with a 255 backed with a 400 on a early model evo cradle. htgsr (Dan) has seen this with his own eyes.

 

[EVO-00X]

Attached is an example I whipped up if using 6AN fittings and 3/8" tubing to connect to a 255Lph (or future 400Lph) intank Walbro fuel pump.

Summit Racing has an awesome kit that's real value for money!!. See their fuel line combination kit number SUM-PUMPKIT2 at this link: http://www.summitrac...tComboContents/
You can use the tube nut and sleeve fittings in that kit to attach to the alloy tube if you want, but you will need to flare both ends of the tube to use them - that's OK if you have a flaring tool available.
If you dont have a flaring tool you can possibly buy separate fuel line adapters to 6AN male connections as an alternative. These use the compression method to connect the special fittings to the tube without the need for flaring the ends. - Edit.

Parts marked with a green 'X' are parts you will either need to buy or consider as an alternative depending on your personal preference.
Please note: I havent physically tried to fit the bulkhead setup on our GSR/EVO fuel pump cradles yet therefore cannot confirm at this stage if it will fit. If I find out that it cannot, I'll nut out another alternative from the bulkhead to the fuelpump

As stated previously, the entire kit as Ive drawn up, plus the additional extra adapters marked with the green "X", can be had for around $200AU delivered!!!
This obviously excludes the fuel filter and the Walbro fuel pump.

 

[brisvr4]

Rob, please be aware that the MAX psi rating for the non flared fittings is either 25psi for the low pressure fitting and 50psi for the higher rated pieces according to Earls.
I looked at these instead of tube nut setups at first but I wouldn't trust them myself. Tube flaring is dead easy and you can pick up the flaring kit from bunnings for bugger all.
I flarded mine lying on my back under the car!
The standard flaring tool isn't 37deg but when you pull the nut tight the tubing will conform.
I tested mine to a touch over 100psi to make sure there weren't any leaks.

 

[4piknup]

I'd be agreeing with brisvr4, instead of messing around with the expense of bulkhead fittings, I will/would be replicating the factory setup in 3/8 steel pipe and flaring the ends. I read a article about it ages ago. You remove factory pipe through the top of cradle and peen the hole larger to accept the 3/8 pipe. Your hole should be funnel shaped. Position pipe and solder in position. All good.
I haven't investigated it yet, but that is my plan. I have already adapted the top of tank piping to accept the proton fuel lines. But a wiring and piping upgrade is in the future.
Can always double flare the pipes if you think a single flare isn't enough. Brake lines must be double flared.

 

[lozza]

yes that is exactly how I did mine (using TIG) before i switched to external set-up. the tricky bit is not torching the plastic electrical adaptor because this can't be removed.

for anyone who cares about this sort of stuff - i did calcs for my fuel set-up. Based on 270lph @ 75psi, -6AN hose, 3/8" bundy tube + associated 90/45's (using i.d. of hose and tube) I came up with a pressure drop of around 1.5psi. If you then add back the loss of the short initial 90 from the pump coming out of the cradle - being 5/16", it is less than 0.5psi drop. total = 2psi total drop which is perfectly acceptable. Conclusion is there not much advantage in replacing this short section (5/16") from the pump to the cradle outlet. People think that these little restrictions (bottlenecks) determine the overall flow, they don't. Rather - they just contribute to overall pressure drop.

So in this case, the pump creates 75psi and the fuel rail sees 73psi. . (-8AN shows less than 1psi for this set-up)

Anyway, most people don't give a shit about all the numbers but that's how I worked mine out.

 

[4piknup]

I cant see it like that lozza, if I had a 3.5" exhaust with a 3" exhaust tip, I would do all in my power to replace the tip.
In the case of that fuel line, I would be tempted to run 1/2 line out of the tank, because of the bends.
That plastic plug is a pain, it must be crimped tight at factory or something.
Nice work on measuring the results of your work. I always love the before and after measurements.

 

[4piknup]

Lozza, Am I correct in my thinking that by your calculations, that 2m of -6 pipe and elbows is 3x more restrictive than 6" of -5?
I know that the walls of pipe are a restriction and I find this pretty interesting

Would be awesome if we could run the pump with unregulated alternator voltage. Ie, 17v+, but without frying the battery

 

[EVO-00X]

Thanks for clarifying about those compression fittings Tim . I mentioned them as Ive seen them being used in fuel setups and hydraulic applications before which I was certain was rated to more pressure than that? But seeing as the kit comes with flare tube nuts and sleeves anyway, we'll stick to the original intention of the kit and use the flared ends. Ive removed the references to the compression fittings in my post above to save on any confusion. Oh, a friend of mine has both the 37' AN and 45' standard double flaring tools so flaring wont be a problem when cloning the new lines side by side whilst off the car lol...

Jack, there isnt really a problem with the added expense of a bulkhead union as it only costs $8.95, and the nut $2.95. Add a dowty seal and the barbed end and it'll be around $15-$20 all up. A bulkhead will allow you to rotate it at any angle to suit the direction of what you are connecting it to which is a plus. It also saves trying to weld next to the white plastic plug on the cradle which is a tight squeeze and requires a slight offset of the bulkhead hole to make it fit. The downside will be if its too long - something I'll need to trial and error. If you want to drill yours out and peen an indentation to tig up an alloy hose through the cover then thats a pretty good method too (some of us dont have the luxury of a tig lol). Either way will work as theres no right or wrong way. It still might be the way to go as you can keep the piping short and have the fuel pump sit up higher in the fuel tank. Im going to trial the bulkhead first and if it doesnt work I'll try your method on a spare cradle. Im sure I'll find plenty of uses for a spare bulkhead in the plumbing somewhere lol

Lozza, Im not sure what fuel requirements I'll need in future (E85, sunflower oil, rocket fuel etc) therefore I'll be more content to keep the same diameter line all the way through as removing the small restrictions will help reduce pressure loss a tiny bit. Plus if you're already 95% got the job done you might as well finish it off lol. Naa, the OEM hard fuel line fittings/couplers on the hoses straight after the fuel pump cradle are shithouse. The couplers corrode and seize together and cannot be unscrewed from eachother. Trying to separate the couplers (or when some people try to remove and refit an intank fuel pump), due to the lack of space to work in they can unintentionally bend and crease the OEM hard line which vertically exits the top of the fuel cradle, thus creating an even greater restriction. You cant bend it back to shape as it will crack. Imagine bending a drinking straw sideways as its much the same. The fittings and piping there have frustrated many GSR/EVO owners and wreckers over the years, yours truly included lol... :lol: :lol: :lol:

 

[brisvr4]

No worries Rob.
With the flares you should only need a single flare though, I tried double flares and it's a bit tight for one in there.
Jack, look up Corky Bell boost a pump mate. It lets you run your pump with a constant high voltage for more flow.

 

[4piknup]

I would be using steel bundy tube through the tank top and soldering into position, I would be worried about thinning the tube with the tig. Maybe brazing as a option.

Although there is plenty of room for bulkheads above my tank, I can actually get my arm above the tank to plug/unplug connectors, so it's probably easier for me to use bulkheads, and thanks for the info I will be considering them. (there is no access panel in the ute tray)
I'm sure if the evo are close to the access panel, you could space the tank down nearly an inch., and/or lift the access panel higher.

 

[lozza]

The fittings and piping there have frustrated many GSR/EVO owners and wreckers over the years, yours truly included lol... :lol: :lol: :lol:

yep me too - i tried and failed. bloody burnt the plastic plug, distorted the metal lid. ended up going external - now i've got 2 noisy farking pumps sitting under the boot !

Lozza, Am I correct in my thinking that by your calculations, that 2m of -6 pipe and elbows is 3x more restrictive than 6" of -5?

approx. yes since the 2m of -6 is straight and the -5 has an entry from the pump, change in diameter and a 90 degree elbow. you can't work it out exactly because what you need is the data from the company that makes the fittings. they're called loss co-efficients and each time a fluid goes in/out a pipe, around a corner, through a valve, into a different size pipe - there's a pressure drop. these are called minor losses and in our fuel systems don't contribute much unless there are heaps (that's why i made the comment about the cradle fitting alone not being that significant overall)
the other type of loss is called major loss - pressure drop that is related to the friction of the pipe/hose walls and this (usually) outways the losses from fittings. so in our systems (if you keep bends/fittings to a minimum) the pipe diameter is the most important. the relationship is squared so if you go from -8 to -4 you get 4 times the pressure drop. the other pressure losses (elevation/kinetic) I didn't look as they're small.

all this shit is exactly the same for large water pipes/pumps but the theory is exactly the same. For most people it doesn't really matter because it's been done a certain way with success and it's always good to over-do (to an extent) the fuel system to be safe. key is - just don't run out of pump.

Say for example you go to E85 and have -6AN. Logically you should probably go to -8AN and run 2 pumps. If you can accept the pressure loss then you may not need to upgrade line size since the 2 pumps will flow double - less say 10% flow for the increase in system pressure from not upgrading the lines. there will likely still be heaps of fuel flow available to feed those hungry injectors. when (if) Perth ever gets E85 i'll have to work it out - i'll do that another time

 

[clone]

what pumps fit the GSR cradle? does the Aeromotive Stealth 340 fit?

 

[ENGINR]

I've been using a Walbro 255 in-tank pump with a Bosch044 external and have -6AN braided line running through the cabin (because RACECAR!) and that setup supports 293kw atw with E85.

 

[EVO-00X]

I had looked at using off the shelf fittings for the fuel pump cradle lid but bulkheads and straight barbed fittings end up being too long (see pic of fittings next to fuel pump cradle).
Therefore recently I have been in communication with Speedflow fittings about developing a new fitting specifically for use for internal fuel pumps and cradles and they sound pretty keen to put my idea into production . Not that it was a big achievement as its pretty basic really - its just a short 90 degree bulkhead up top and a short barb -6AN fitting on the bottom as a one piece unit that'll bolt through a fuel cradle lid and be more compact than using 2 separate fittings (see big collage of pics). They said that they can make them easily and are going to prototype one up first
Ive got a spare evo cradle to drill out a 14mm hole in the top of the cradle next to the plastic plug, then trial fit the new Speedflow fitting and a 400lhp Walbro fuel pump when the time comes
In the meantime I changed a few different things with my connections that I mentioned earlier. I think with a decent fitting like this we will be able to raise the fuel pumps up a bit in the cradle.

As far as the fuel feed lines go, I am now using my original fuel feed line as my fuel return line, and the original fuel return line was removed and replaced with the 3/8" alloy tubing and it will be my new fuel feed line. Its all been bent up to install in the factory position under the car. The oem plastic underbody brackets had the outer UUUUU channel enlarged with a soldering iron to squeeze click the new 3/8" tubing into place. The alloy tubing is sitting in the factory position right now.

 

[clone]

Okay so what pumps will fit exactly in my cradle ? As my pump is sounding like an old blender .

 

[4piknup]

3/8 is -6
this must be able to support 400 ish atw kw on 98 Ron.

 

[DOUGMO]

Okay so what pumps will fit exactly in my cradle ? As my pump is sounding like an old blender .

walbro 255

for the record I run two -6 feed lines from twin 044s with a -8 return, carter lift pump