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  • fuel pressure recommendations?

    my 454 with 44# injectors is seeing 30psi at the rail. i was going to set the adjustment higher. how high should I go? I see a 5-10psi drop when I romp it but it comes right back within seconds.

  • #2
    Recommended Fuel Pressure for Pro Flo 2/XT

    32-38 PSI engine idling with manifold vacuum hooked to the fuel pressure regulator diaphragm.

    42-45 PSI key on/engine off (this means 42-45 PSI at WOT too)

    Higher HP kits with an adjustable regulator are set to 50 PSI with no vacuum reference. Just leave the diaphragm open to atmospheric pressure.

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    • #3
      Thanx Jeff, helpful as always. Does the higher pressure insure the injectors are not starving for fuel? How much does it affect the fuel maps?

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      • #4
        For example: Your 44 lb./hr. injector is rated to flow 44 lb./hr. @ 43.5 PSI of fuel pressure.
        @ 30 PSI it will flow 36.54 lb./hr. or 20% less
        @ 50 PSI it will flow 47.17 lb./hr. or 7% more

        So yes, the fuel pressure has an effect on the fuel map and how rich or lean the engine may run.

        All Pro Flo, Pro Flo 2, & Pro Flo XT systems with a non-adjustable fuel pressure regulator use this spec.
        32-38 PSI engine idling with manifold vacuum hooked to the fuel pressure regulator diaphragm.

        42-45 PSI key on/engine off (this means 42-45 PSI at WOT too)
        All Pro Flo 2 & Pro Flo XT systems with an adjustable fuel pressure regulator and 60 lb./hr. injectors use this spec.
        Higher HP kits with an adjustable regulator are set to 50 PSI with no vacuum reference. Just leave the diaphragm open to atmospheric pressure.
        Note: All system base maps were tuned using the correlating specs above.

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        • #5
          Pro=Flo2 considered high hp?

          Just to clarify, is the regulator on a Pro-Flo 2 system supposed to be open to atmosphere?

          Thanks,
          Jim

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          • #6
            All Pro Flo and Pro Flo 2/XT systems with a nonadjustable fuel pressure regulator should be referenced to manifold vacuum.

            All Pro Flo 2/XT systems with adjustable regulators set to 50 PSI should be referenced to atmosphere.

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            • #7
              not normally, but

              normally the regulator is vacuum adjusted. I got tired of chasing my A/F ratio's all over the place so I have mine open the atmosphere and have the fuel pressure remain constant so the amount of fuel doesn't constantly change. I also drilled out the orifice to increase the fuel pressure to 50 PSI. The increased fuel pressure necessitates a reduction in the amount of time the injectors are on. Doing this allowed me to closely control my A/F ratio. I also have tuned my temp coefficient tables to minimize the variation that the factory tables have. My system now runs much better and I have increased my fuel economy by ~25% (from 12mpg to 17mpg). Hope this helps!

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