Fuel line and regulator plumbing to EFI rails

Discussion in 'High Tech Retrofits' started by woody80z28, Nov 21, 2016.

  1. woody80z28

    woody80z28 Veteran Member Lifetime Gold Member

    5,418
    11
    Sep 8, 2004
    walton, ny usa
    Doing some mock up work and struggling to come up with a solution I like. Needs to be NHRA legal because I'll be racing. I also don't want to send all the fuel through the rails and cause a hot circulation problem on long trips like people have run into on Power Tour.

    I'm definitely running hard line from the tank to the engine bay on the outside of the rail away from the exhaust. Going to transition from steel to hose at -6AN bulkheads in the little sheet metal piece that connects the inner fenders to the body down by the body mounts. And once it's to the regulator I'm happy with dead-heading the rest of the rails and returning the unused fuel before it goes to them.

    Feeding the rails at the rear seems the cleanest, but I'm worried about legality for NHRA. I know regulators are not allowed on the firewall, but read a post about a 6" rule where they have to be so far forward of the bellhousing. If that's true, this would fail a good tech inspector.
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    Feeding at the front means a lot more hose and it certainly doesn't look as good...whether it's hidden behind (and hard to access) or right on the inner fender. Certainly NHRA legal though. Anyone have a similar setup and a better idea for routing the hoses?
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    I also saw this post on Pro-Touring where you bypass right at the tank and only send a single feed line forward. Lots of guys are doing it with success. Seems less than great to have to crawl under the car to adjust fuel pressure though. My car is gonna be LOW.
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  2. CasperCasper

    CasperCasper Veteran Member

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    Aug 11, 2015
    Personally I like the idea of running the regulator at the tank and a fuel pressure gauge on the rail. That way you can set the regulator at the tank and be pretty sure about your rail pressure. I think your first picture looks great with the regulator mounted at the rear of the rail but I too think that would fail tech.
     
  3. 71RS/SS396

    71RS/SS396 Veteran Member

    2,521
    14
    Aug 26, 2008
    Wake Forest NC
    It's better to have the regulator close to the rails, it will keep the rail pressure more consistent because there's less distance to the injectors. I would also put a "Y" on the output of the regulator and feed both rails instead of just one.
     
  4. fast231

    fast231 Member

    40
    2
    May 13, 2011
    canada
    When I plumbed my fuel system. I have a 1/2 hard line from the pump and filters at the back of the car to the lower pass side inner fender. I ran a -10 line to a y with 2 -8's up to the rear of each rails. At the front of the rails i brought two -8's out of each and into my regulator. Then a -8 return over to the pass fender and ran it to the back of the car and into my cell. I'm not sure what your horse power goals are....I wouldn't dead head one rail....I understood it's best to regulate your fuel "after" your rails.
     
  5. woody80z28

    woody80z28 Veteran Member Lifetime Gold Member

    5,418
    11
    Sep 8, 2004
    walton, ny usa
    That's the debate I see on pro-touring. Some say it's horrible to deadhead the rails, others say bypassing after causes vapor lock on long trips.

    The OEMs have been bypassing before the rails for about 10 years. Guys with big power builds too...some 1000+.

    So I'm definitely doing it also. I plan on Power Tour etc. The main problem is placement of the reg where it's easily accessible.
     
  6. czizza

    czizza Veteran Member

    739
    5
    Jan 8, 2004
    N. Massapequa, NY, USA
    I have my adjustable pressure regulator up front with a split to both rails and an additional split in the back ... so in essence my rails are squared for a lack of better term.

    Here is my setup, if you put the regulator on the fuel pump it will be difficult to adjust.

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  7. hot72rod

    hot72rod Veteran Member Gold Member

    I think what is killing you is all the flex line you have laying across your inner fender. If it was me I would leave the regulator on the front, but instead of using all that flex line. I would use still line up the frame rail like the factory did and the flex line from there.

    Here is a example of how I did it.

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  8. Fbird

    Fbird Veteran Member Lifetime Gold Member

    2,202
    32
    Feb 12, 2011
    atlanta, ga
    i did mine very similar... hard line to the fenderwell...added filter... then flex line to the rail...flex from rail-rail.... then regulator..flex back to hard line

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    must excuse the fuel pressure gauge screwed into the reugulator... :)
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  9. 76_TypeLT

    76_TypeLT Veteran Member Lifetime Gold Member

    6,313
    108
    Jul 26, 2008
    Houston, TX
    Seeing threads like this scares me into wondering if my setup is "ok" or not.

    Mine is fairly simple - filter/regulator near the fuel tank, flex/hard line from filter/regulator to the engine bay, then flex line to the back of the passenger side fuel rail. The passenger side fuel rail is connected to the driver side fuel rail via flex line alone the front connection points.
     
  10. fast231

    fast231 Member

    40
    2
    May 13, 2011
    canada
    It's all about your present and future horse power goals......I built my fuel system to be ready for 800 ish HP at the wheels. Presently 620 to the wheels and my 120lb injectors run about 30% duty cycle at the top end of the track.
     

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