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Thread: New Project Dual Quad Sniper - Fuel System Question

  1. #11

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    Regulator before the throttle body here and no issues at all. Roughly 850 horsepower boosted. I spoke to Aeromotive beforehand and they said it would work well, and it has.

  2. #12

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    @gregs69rs: Being boosted is a different story assuming you have a boost referenced regulator, but still the same problem.

    Why would you not want to regulate after the load? As of now your not accounting for the pressure drop from the injectors.

    Looks obvious to me some people get away with the plumbing this way and I'm sure there are some reasons for it. Such as manifold pressure referenced regulators and I assume pumps that are capable of much more volume than is needed.

    Think about if you regulated your electrical system in the same manner. Put the regulator before the load at 14 volts, then turn on all loads, the voltage would drop well below the desired point due to the voltage regulator being on the wrong side of the load.

    Have you ever put a pressure gauge after the regulator and before the injectors? I think you would be surprised to see what happens to the pressure when you snap the throttle.

    Then again maybe whoever you spoke with at Aeromotive understands what happens to the pressure & volume, before & after a restriction in a manner which defies the basic laws of physics? Then again I may be off my rocker.

    One of the reasons a regulator is used before a carburetor is to protect the needle from unseating under excessive pressure, and a carb has a well of fuel to draw from mostly independent of pressure and volume within reason of understanding of it's operation. If you regulate the pressure before a fuel injector and keep the injector seated then the pressure will be the same before the regulator and after, up to the seat of the injector. As soon as the injector moves the pintle of it's seat, the restriction changes (less restriction) and so does the pressure (less pressure). Of course we know volume increases after a restriction and as of now I assume this is being accounted for by a pump that's more than capable. I'm going to guess the pump would need to be 20 to 30% over sized at a minimum to overcome the regulator before the injector.

  3. #13

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    @ABC: I think all of the OEMs put the regulator in the gas tank these days. The regulator adjusts for the downstream pressure so line pressure stays steady regardless of fuel flow.

  4. #14

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    I concur with Andy on this. The bulk of EFI systems are returnless now-a-days. The regulator is in the fuel pump assembly buried inside the fuel tank. I opted to keep my low pressure pump setup at the tank and run it to a G-surge unit placed closer to the engine. My low pressure pump is setup for a return back to the tank and the G-surge unit is deadheaded to the Sniper. The Sniper seems to work just fine deadheaded. In hindsight, one of those trick in-tank setups seems to be the better solution and if I was building something from scratch, that would be the direction I would go.

  5. #15

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    Quote Originally Posted by AndyF View Post
    @ABC: I think all of the OEMs put the regulator in the gas tank these days. The regulator adjusts for the downstream pressure so line pressure stays steady regardless of fuel flow.
    All true.

    Quote Originally Posted by Gen2Van View Post
    I concur with Andy on this. The bulk of EFI systems are return-less now-a-days. The regulator is in the fuel pump assembly buried inside the fuel tank.
    Also true. As you both know, the OEM systems are dead headed and the return is at the pump/in the tank. I still forget that's an excellent option for these retrofitted hot rods.

    I guess I did jump to an assumption, when people talk about putting a regulator before the fuel rail, they're also using a return from the fuel rail, that's obviously wrong of me. I'll correct and amend my statement: If you're going to use a full return type system, the regulator should be after the fuel rail.

  6. #16
    Join Date
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    OEM returnless are NOT deadheaded regulators at all! The regulator is not a restriction to fuel flow, like a "Deadheaded" carburetor regulator. The in-tank regulators control the fuel pressure within the line by dumping fuel as necessary to keep the fuel pressure at the target. The OEMs were the first to work this out, we don't need a return line, and can compensate for no vacuum referencing with ECU programming. Plastic fuel tanks, plastic fuel lines, no return circulation, lower fuel temps. Gary

  7. #17
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    Thank you Gary! I just wasn't motivated to explain that again. (Yes, we've discussed this before.)

  8. #18
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    You're welcome Danny. Glad to help. Gary

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