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Thread: LS7 flow restriction issues and vacuum at WOT

  1. #1
    Tuner in Training
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    LS7 flow restriction issues and vacuum at WOT

    Hello,

    I've logged my C6 Z06 on a few pulls. I'm pulling about 9 kpa worth of vacuum at WOT.

    I have a ported stock throttle body, corsa air intake, and a ported MSD manifold.

    Does anyone have any suggestions as to whether my 90mm throttle body is truly restrictive at this point?

    Also, how do I convert injector pulse width average to IDC?

    Car makes around 600 rwhp.

    MAP at 95kpa with baro 104kpa, atm 102kpa.

    Please see the snapshot:

    95kpa.png
    Last edited by wolf8218; 04-11-2019 at 09:49 AM.

  2. #2
    Tuning Addict 5FDP's Avatar
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    Just floating by here, the log does show your IDC already. It's at 94%.
    2016 Silverado CCSB 5.3/6L80e, not as slow but still heavy.

  3. #3
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    I have also seen LS3 with big cams do this at high RPM. pulling up to 5KPA vacuum at WOT.

    I fitted fast manifolds, removed air intake etc... no difference over stock but still make good power.

    yours being 7.0 would be worse than what I've seen with 6.2.

    I put it down to either throttle body needing to be 102 or it needing a high rise ram style inlet to support the RPM flow

  4. #4
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    Would 94% be safe to run? I've heard many answers but none with any sort of scientific explanation vs being preference of the user.

    If I'm restricted at 6000 rpm, would I start to run out of fuel if I remove the restriction?

    Quote Originally Posted by lukearmstrong1990 View Post
    I have also seen LS3 with big cams do this at high RPM. pulling up to 5KPA vacuum at WOT.

    I fitted fast manifolds, removed air intake etc... no difference over stock but still make good power.

    yours being 7.0 would be worse than what I've seen with 6.2.

    I put it down to either throttle body needing to be 102 or it needing a high rise ram style inlet to support the RPM flow
    Theres not many options available that fit inside the hood, no?

    My cam isn't that big .638 .651 113 17 deg overlap

  5. #5
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    bump

  6. #6
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    bump

  7. #7
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    bump

  8. #8
    94% idc is more than I'd be comfortable running. When your injectors are basically open 100% of the time you can overheat and damage the injector drivers on the ecu. If you remove the restriction in the air inlet your problem would only get worse

  9. #9
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    Scott, what injectors would you run? I don't want to run E85. I'm only at around 11.7:1 and I don't think it would benefit me that much, plus I don't feel like dropping the tank for a new pump.

  10. #10
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    I'd get a set of ID 850s

  11. #11
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    Are my injector pulses getting too long? I'm assuming they're longer because they're running out of bandwidth, therefore tuning around valve events gets harder?

  12. #12
    Quote Originally Posted by DougO View Post
    I'd get a set of ID 850s
    I'd go with these or at least something with 60 lb/hr minimum. But go with something you can get good injector data with.

  13. #13
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    Quote Originally Posted by Scottgt21 View Post
    I'd go with these or at least something with 60 lb/hr minimum. But go with something you can get good injector data with.
    Thank you for your responses.

    I can't afford ID1050x's right now.

    I'm looking at

    • Fuel Injector Connection 60 lb Bosch $460
    • Fuel Injector Clinic 660 CC matched $630
    • Deka 60 lbs $???
    • DeatschWeks 65 lbs $500


    Any advice before I order tomorrow?

  14. #14
    I've had good luck with Fuel injector clinic on other platforms