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Thread: Injector PW & Duty Cycle

  1. #1
    Lifetime Member
    Join Date
    May 2008

    Default Injector PW & Duty Cycle

    In a drag race only vehicle and you hit 100% duty cycle can you raise the fuel pressure 20% (60psi to 72psi) then reduce your MAP VE 20% accross the board and come out the same AFR? Or is their a different formula to use without starting over on the VE tables?



    230" Dragster - 2000 LS1, 02020003 Speed Density, PRC 2.5 Heads,
    MS3 Cam 237/242 .603/.609, Vic Jr. intake, Holley 1000CFM TB,
    PowerGlide, 5000 stall converter. 8.70@154 MPH

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  2. #2
    Lifetime Member ChipsByAl's Avatar
    Join Date
    Feb 2006


    Sorry Lee but it does not work like that. Fuel pressure rise vs. delivered fuel through the injectors is not a linear equation. Check out Russ Collins' web page for an online formula.
    To be accurate after any fuel changes you should put a wide band AFM to verify the change.
    "Trash that carb and get Injected!"

  3. #3
    Member Ritch's Avatar
    Join Date
    Feb 2007


    any concerns about increasing pressure to 70+ lbs? I am considering this.
    1999 GMC, rcsb, 2wd, 5.3, XR275HR-12
    Radix magnacharger mp112
    Long tubes true duals, $L60E

  4. #4
    Lifetime Member johnv's Avatar
    Join Date
    Jan 2005


    If your VE table is dialed in you should be able to raise fuel pressure, then rescale injector flow rate table useing one of the spread sheets floating around (do a search)

    then you should be good to go
    Back yard boost
    347+ T76 = 770 rwhp 10.96 @ 135 mph

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