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Old 10-21-2010, 11:02 PM   #1
dexterous
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Default Need larger fuel lines, should I delete the EVAP system and use all three hard lines?

I have recently purchased an Element Tuning Pro Comp motor and I am in the process of piecing together a setup that should be more than capable of 500whp on a mustang dyno. My new setup is obviously going to need a lot of fuel so I have read just about very thread on NASIOC regarding upgraded fuel systems. In addition, I have spent time on the phone with Aeromotive and my tuner (Phil from Element) trying to pin down an exact design that will support my setup while trying to keep costs down. At this point, I think I have addressed just about every issue, question and concern accept one.

All my research indicates that the factory 5/16 fuel feed line between the A1000 fuel pump and the fuel rails is going to be inadequate. Based on a ton of research I have come to the conclusion that I dont want to run new fuel line for a multitude of reasons (safety, corrosion, etc). Based on this desire no retain the factory hard lines I started to wonder about reconfiguring the fuel system so that the standard factory fuel evap purge solenoid breather line was setup to act as a fuel return line. This would allow the factory return line to become a second feed line thus doubling the car's capacity to deliver fuel to the motor.

Based on close examination of my car it appears that the evap purge solenoid breather line (from here on out referred to as simply "the breather line") is constructed of identical materials as the factory fuel feed line and return line (All 5/16 hard line). Since I run a Hydra with no ODB2 capabilities the electronic pieces of the evap system are no used making the evap system pretty easy to delete.

Has anybody ever setup a Subaru like this? Google tells me that there are a few Evo owners that are running around with very high power levels that are configured like this (2x fuel feeds and former breather line running as a return.

I have attached a diagram of the fuel system that I plan on building using all three hard lines. I would appreciate any thoughts, experience and feedback you guys can give me. Thanks!

P.S. Lets stay closely on the topic of the fuel feed and return setup. I know exactly how to remove the EVAP system, etc.

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Old 10-22-2010, 12:41 AM   #2
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Most of the builders in my area have told me they prefer series plumbing as it has less chance of vapor issues. Otherwise I would only t the lines together and then into one rail and series.

FWIW what I did on my system was used the factory lines with a wally in tank to feed to the front and relocated the batt to the rear and put a swirl pot where the batt used to go. then put two 044's up front in a safe location under the hood and feed the rails back to the swirl pot. Then at the top of the swirl pot connected the factory return line.

Keep in mind the wally only has line head presure which is 5-10psi max and at that low of a presure it moves ALOT of fuel.
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Old 10-22-2010, 12:38 PM   #3
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To be honest its easier to just run a 5/8ths or 1/2" line up the the front of the car,and 1/2" or 3/8 line as a return.
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Old 10-22-2010, 12:51 PM   #4
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Run larger Stainless Steel Braided Lines in place of the factory ones. It may cost some money, but it would make you life alot easier I feel.
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Old 10-22-2010, 01:10 PM   #5
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When I was building my fuel system, I almost went that same route you have listed above. In hindsight I should have as it would have made for a cleaner install.

Earls sells fittings that slip over the factory 5/16th hard lines which allow you to use AN plumbing along with the factory lines.

http://www.jegs.com/i/Earl's/361/165056/10002/-1

Last edited by ec2k1gt; 10-22-2010 at 01:25 PM.
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Old 10-22-2010, 11:32 PM   #6
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Yeah, I totally agree on the clean install. After pricing everything out I discovered that it was only going to save me $60 verses the price of just running the -10 line. Its really not what I wanted to do but I just picked up the -10 line.
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Old 10-23-2010, 12:10 AM   #7
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what research did you do that said your factory line would be inadequate?Dave B. told me himself that the factory fuel line was good to 1000 crank hp.I am sitting at about 700whp with the stock lines and 2 modded walbros on e85 and idc's on the id2200's is only 63-64% at 29-30 psi.I trust what Phil says but its up to you what you will be comfortable with. good luck
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Old 10-23-2010, 05:57 AM   #8
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Quote:
Originally Posted by dexterous View Post
Yeah, I totally agree on the clean install. After pricing everything out I discovered that it was only going to save me $60 verses the price of just running the -10 line. Its really not what I wanted to do but I just picked up the -10 line.
-10 feed line? That's massive.
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Old 10-23-2010, 11:01 AM   #9
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Quote:
Originally Posted by alcoolaid View Post
-10 feed line? That's massive.
When you use an A1000 you need a large feed line and return, moving fuel through the pump is what keeps it cool.
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Old 01-14-2011, 06:38 AM   #10
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Quote:
Originally Posted by john 1badSTI
what research did you do that said your factory line would be inadequate?Dave B. told me himself that the factory fuel line was good to 1000 crank hp.I am sitting at about 700whp with the stock lines and 2 modded walbros on e85 and idc's on the id2200's is only 63-64% at 29-30 psi.I trust what Phil says but its up to you what you will be comfortable with. good luck
At around 600 HP on e85 the stock lines are not suitable because you need at least -8 feed and -6 return
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Old 01-14-2011, 04:03 PM   #11
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Quote:
Originally Posted by ec2k1gt View Post
When I was building my fuel system, I almost went that same route you have listed above. In hindsight I should have as it would have made for a cleaner install.

Earls sells fittings that slip over the factory 5/16th hard lines which allow you to use AN plumbing along with the factory lines.

http://www.jegs.com/i/Earl's/361/165056/10002/-1
Its only rated to 50psi, its easy to have 70psi fuel pressure during WOT and a good turbo.
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Old 01-14-2011, 06:16 PM   #12
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Running 1/2" stainless >-8 feed and 3/8" stainless>-6 return with an A1000. So far so good.
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Old 01-14-2011, 11:02 PM   #13
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Quote:
Originally Posted by john 1badSTI View Post
what research did you do that said your factory line would be inadequate?Dave B. told me himself that the factory fuel line was good to 1000 crank hp.I am sitting at about 700whp with the stock lines and 2 modded walbros on e85 and idc's on the id2200's is only 63-64% at 29-30 psi.I trust what Phil says but its up to you what you will be comfortable with. good luck
^agreed
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Old 01-14-2011, 11:51 PM   #14
john 1badSTI
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Quote:
Originally Posted by sorrowfulkiller View Post
At around 600 HP on e85 the stock lines are not suitable because you need at least -8 feed and -6 return
well I hate to tell you this but buschur's evo is sitting at 740whp on HIS mustang dyno using the factory lines.And I am way above what you say with no signs of any limitations.
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Old 04-03-2011, 12:44 PM   #15
dexterous
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To bring this back to life a bit, I decided to just go with the larger lines. I was pretty frustrated by the conflicting information regarding the need for an upgrade (still am). I have read a lot of stuff that Dave Buschur has posted (and other highly reputable people) saying that the stock lines were fine. I have also read an equal number of things from equally knowledgeable tuners/builders who say the exact opposite. Whats the right answer since everybody has a different opinion?

Even though I went with the large lines I didn't decide to specifically agree or disagree with either side. I just assumed that the larger lines would be fairly harmless and would remove the possibility of trouble from that aspect of my build.

For people searching on this, NEVER install anything other than PTFE lines and ALWAYS use hose ends form the hose manufacturer that were designed for the exact hose you will be using (never mix brands, EVER). Failure to follow this advice will cause leaks, fuel smell in the car and dangerous conditions.

Here's a good place to buy everything:
http://www.siliconeintakes.com/index...9d8972fe980cb1


You should expect to pay $130 for a simple trunk to engine bay setup and as much as $500 to do the entire fuel system if using the vendor posted above.

Here's the install for reference, -10 feed and -6 return:












Last edited by dexterous; 04-03-2011 at 12:50 PM.
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Old 04-03-2011, 07:31 PM   #16
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I am going to try using the evap line as a secondary feed line in my car. Just ordered all the lines and fittings to do it. I have dual walbros and will run a -6 from each pump to each 5/16" hardline, then merge into a single -8 in the engine bay. Later on I'll prolly add inline bosch 044's or switch the walbro's to aeromotive 340's.
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Old 04-03-2011, 07:56 PM   #17
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just make sure the lines aren't pinched by those sleeve clamps
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Old 04-08-2011, 11:42 PM   #18
dexterous
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Nope, it just looked bad in that second pict because it was during the install and I didn't have everything in place yet.
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Old 04-09-2011, 03:09 AM   #19
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If you ever find conflicting information about what is or is not adequate, just go to the equations and calculate things for yourself. Thinking for yourself is never overrated, and often you'll find that what a lot of people do and say is "perfectly fine" is actually ridiculously dangerous. Whether they know it or not is a different matter, the fact is that a lot of reputable tuners do things with their customers cars that would make you shudder if you knew the details.


As for factory fuel lines...the pressure loss depends on a few things, namely the diameter of the line, density of the fuel, viscosity of the fuel, and velocity of the fuel. The density and viscosity are easily found by a simple google search, and there are a multitude of calculators out there (also found with a simple google search) that will do all of the calculations for you.

I haven't done every combination, obviously, but a single Walbro 255 at a typical boost pressure of 20 psi will flow in the neighborhood of 210 L/hr. With the factory 5/16 line, this equates to a .1 psi drop per foot. It does not matter how much fuel you use, the only thing that matters is how much fuel your pump(s) is flowing, including that which is bypassed and returned to the tank. A Walbro 255 drops .1 psi per foot on the factory lines. A Bosch 044 is more like .14 psi per foot. Twin walbro 255s will be closer to .4 psi per foot (restriction rises with velocity squared).

Now you might be thinking to yourself that there is only about 12 feet of fuel line between the pump and the manifold, which equates to a 1.2, 1.7, and 4.8 psi drop respectively (Walbro, Bosch, twin Walbro). In the grand scheme of things this isn't too bad, it simply means that if your FPR is holding you at 70 psi, your pump has to deliver the flow into 70+(1.2, 1.7, or 4.8) psi.

However, the factory rails are a big problem. Series routing, small lines, lots of snaking (added loss plus added length). You're looking at somewhere around .5 psi pressure difference between the first and last injector on a single Walbro 255 (1.1% fueling difference), .8 psi (1.5% difference) for a Bosch 044, and 2 psi (4.4% difference) for twin Walbro 255.

How much is 4.4% difference? It means the difference between 11.0 at cylinder 2 and 11.5 at cylinder 3. Anybody who thinks that's perfectly fine needs to get their head checked.
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Old 04-09-2011, 08:39 AM   #20
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Well, I'm glad I went with the big lines then!
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