Fuel system plumbing

03 Cobra DSG

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While I’m doing a turbo swap, building a motor, switching to a Holley, etc. I needed to do some upgrades on the fuel system. The way it used to be setup ( from the previous owner) I did have fuel pressure fluctuations and the fuel was getting pretty hot. I’m also switching to e85. So I have new ti auto 465 pumps, FIC 2150’s and all fore parts. I’ve attached a diagram how I want to run it. I’ll be moving the regulator into the fender to keep it cooler along with the y-block just making sure I’m not missing something or if I should route it a different way. I’m open to suggestions thanks.
IMG_7054.JPG



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03' White Snake

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Why run fuel lines to the front, why not feed each rail from the back?

Mine is done like this and is much cleaner IMO. From wye block into the rear of each rail. No crossover tube between rails.
 

03 Cobra DSG

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Why run fuel lines to the front, why not feed each rail from the back?

Mine is done like this and is much cleaner IMO. From wye block into the rear of each rail. No crossover tube between rails.
I figured running the lines to the front if I had to remove the intake it would be easier than undoing the lines in the rear.
 

03' White Snake

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I figured running the lines to the front if I had to remove the intake it would be easier than undoing the lines in the rear.

I just remove the feed line into the wye block and remove the entire blower and lower intake with the lines and rails still attached. My wye is located on the rear fire wall, so the lines are not crazy long like yours would be with the wye block in the fender.
 

Soap

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For ease of packaging you should consider -8 from the Y block to each rail and -8 for your crossover tube between the rails. -10 fittings and line are significantly larger than -8 and there is not much room.

You will not have a fuel volume issue with the -8.

--Joe
 

96dreamer

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I am running a setup similar to your first picture. However I have -8 from the y block to the back of the rails with a -6 crossover in the front. Two -8's flow more than one -10 going into the y so there's no restriction there and the -6 cross over isn't really flowing anything significant so the size really doesn't matter. On your worry of intake removal I remove the -10 from the regulator in the fender and pull everything attached to the intake in one go. I try not to make a habit of pulling it to much anyway.
 

Albatross

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Is a -10 feed line necessary when going into a y-block feeding two individual -8 lines to the rails? Or would it be ok to run -8 feed?
 

96dreamer

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Is a -10 feed line necessary when going into a y-block feeding two individual -8 lines to the rails? Or would it be ok to run -8 feed?
For PTFE line the cross sectional area of -10 is ~.21in^2 and -8 is ~.13in^2. So running two -8 lines will outflow a single -10 which is your restriction at that point. Therefore bumping up to two -10's will not improve anything at that point in the system. If running e85 I would suggest sticking with a -10 feed over -8 to the regulator/y block. The fittings and line is not that much more for the added capacity it provides to the system.
 

01yellercobra

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FWIW, when I ordered my system I was planning on going with -10 feed and -8 return. Both Fore and Malcolm said I would be fine with -8. I was told my current fuel system is good for 800rwhp on E85. I doubt I'll ever make that much so I'm good. At least with the blower.

And remember, a turbo car doesn't need as much fuel system as a blower car.
 

Albatross

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@01yellercobra Are you running a deadhead/parallel style or flow through/series style setup?

I guess I'm more curious to know if, when running a deadhead setup with the rails plumbed in parallel, is a -10 required up to the y-block in order to supply enough fuel to the two -8 lines running to each rail. Or would a -8 from the tank supply enough fuel up to the y?
 

01yellercobra

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@01yellercobra Are you running a deadhead/parallel style or flow through/series style setup?

I guess I'm more curious to know if, when running a deadhead setup with the rails plumbed in parallel, is a -10 required up to the y-block in order to supply enough fuel to the two -8 lines running to each rail. Or would a -8 from the tank supply enough fuel up to the y?
I'm running a deadhead system. -8 lines all around. The feed line connects to the passenger rail at the front, crossover in back, and the driver side is plugged in the front.

For my buddies car the feed line connects in the same place, has the cross over in the back, and then a return line goes from the driver side front rail to the regulator under the JLT then back to the tank.

Neither one of us have any fuel issues.
 

SecondhandSnake

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Mine isn't that typical, but I'm running a deadhead setup, huge external pump, tons of E85. -10 supply line to regulator in the passenger side fender, to a Y-block, two -8 lines to the back of the rails, -8 from the regulator to the tank. I probably could have gone way smaller on the return line.

I would have no worries about running two -8 lines from the Y block to the rails. As it was mentioned, they will outflow the -10 supply line.

No issues with heat. I ran mine for quite awhile, light load so it's getting the most return fuel, and never saw temperatures get above 10 deg F higher than ambient temperature.
 

03' White Snake

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-10 feed from tank to regulator, -10 into Y-block, -8 feeding the rear of each rail dead head, no crossover with -8 return line to tank. 2 465 pumps, making 823hp/ 767tq on 22 psi on corn. No issues.

Buy once, cry once. Spend the tiny bit extra and run -10 line and be done with it.
 

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