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Boost issues

Discussion in 'Turbo Tech Questions' started by coilz347, Nov 21, 2022.

  1. coilz347

    Joined:
    Feb 5, 2004
    Hi guys,

    I have a 93 coupe with a 410 Windsor, afr205, fti cam, spyder intake, 80lb injectors and a tkx transmission. I just recently upgraded my turbo from a 78/75 t4 cast wheel and a .96ar to a 78/85 with a billet wheel and a 1.25ar.

    on our last track outing I tried upping the boost from 9-10psi to 14-15psi

    as soon as the turbo would spool it would spike 15psi and then quickly flatten out to 10psi where I’d shift near 6000

    is this a waste gate, turbo or back pressure issue.

    I never noticed this with the smaller turbo but I also never ran more then 10psi with it either.

    thanks for the help
     
    coilz347, Nov 21, 2022
    #1

  2. Mnlx

    Joined:
    Sep 20, 2009
    How are you controlling boost? I'm guessing the 7875 is struggling with back pressure on that combo, but a simple controller change may help.
     
    Mnlx, Nov 21, 2022
    #2

  3. F4K

    Joined:
    Jan 7, 2020
    Perform a boost leak test just to ensure you are not leaking all your boost pressure out which will overspin the turbo and create high IAT and lost power, high EGT, could lead to engine destruction.
     
    F4K, Nov 23, 2022
    #3

  4. bbi_turbos

    Joined:
    Dec 8, 2021
    Sounds like wastegate being opened by exhaust pressure to me. What spring is in your w/g?
     
    bbi_turbos, Nov 24, 2022
    #4
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