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Thread: Injection timing

  1. #1
    Potential Tuner
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    Jun 2020
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    Injection timing

    Can anybody help me wrap my head around correct. Injector timing I'm sure it's been discussed. ...I'm new to this ls 408. Comp cam @50 296/312 on a 114 624 lift ....

  2. #2
    Advanced Tuner
    Join Date
    Sep 2017
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    In short injection timing is when and how long the injector sprays.
    SOIT (Start of Injection Timing)
    EOIT ( End of Injection Timing).

    Stock ls motors spray early. They spray onto the back of a hot intake valve to cause evaporation and help atomize the fuel better.

    This doesnt work well with a cam like yours with that much overlap.
    Stock ls IT you will be spraying the injector and lose a lot of fuel out the exhaust valve which can cause some issues.

    Your next step would be to determine your valve events. Iirc that cam exhaust valve close at 398?.

    You can delay the injection to start later so you dont lose that fuel out the exhaust.
    Making the SOIT just before, around or after the exhaust valve closes will help clean it up a bit so you arent losing fuel.

    Using a 2002 fbody OS for your cam try moving the boundary to 6.7
    Under normal the operating temps are 5.55 iirc make those 6.55. Im not to sure about the makeup table but stock they mirror the normal so do that as well.
    That should put you around the EVC event.

    Thats all i got today lol
    1997 30th SS. Torqhead 24x, TFS heads, 223/235 cam, 4l80e, S60 D1SC 14psi

  3. #3
    Someone on here actually shared a really nice spreadsheet a while back for setting up injector timing based on valve events if you have accurate cam data including IVO/EVC. I believe this is it...

    turbo 4.8.xlsx

  4. #4
    Advanced Tuner
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    Quote Originally Posted by Evo8john View Post
    Someone on here actually shared a really nice spreadsheet a while back for setting up injector timing based on valve events if you have accurate cam data including IVO/EVC. I believe this is it...

    turbo 4.8.xlsx
    I use ERMs spreedsheet. Its pretty good.
    1997 30th SS. Torqhead 24x, TFS heads, 223/235 cam, 4l80e, S60 D1SC 14psi

  5. #5
    Tuner in Training
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    May 2020
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    I find this more friendly .
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