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Thread: what are the limits for LT4 injector

  1. #1

    what are the limits for LT4 injector

    Good day guys,

    I would like to know what are the limits for LT4 injectors, Pules width & Injector duty cycle ?


    So I can have an Idea when I reach the limit of the injector.


    Thanks you,

  2. #2
    Advanced Tuner Ghostnotes's Avatar
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    Not to hijack but speaking of limits as well, what's a ballpark on horsepower limits if swapping out your LT1's?
    I always tune VVE....
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  3. #3
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    What fuel are you using? What lambda are you targeting? Is the engine stock? Does it have an upgraded cam?

  4. #4
    Quote Originally Posted by cadillactech View Post
    What fuel are you using? What lambda are you targeting? Is the engine stock? Does it have an upgraded cam?
    Pump gas, Targeting around 12 AFR ( 0.80 to 0.85 lambda ), everything is stock
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  5. #5
    Senior Tuner SultanHassanMasTuning's Avatar
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    lets just say your inject PW should past 6ms
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  6. #6
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    Quote Originally Posted by SultanHassanMasTuning View Post
    lets just say your inject PW should past 6ms
    Ya, anything over 6ms and you are out of fuel.
    You say stock everything, is this an LT4 engine?

  7. #7
    Quote Originally Posted by cadillactech View Post
    Ya, anything over 6ms and you are out of fuel.
    You say stock everything, is this an LT4 engine?
    Yes stock LT4 engine on CTS-V
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  8. #8
    Senior Tuner LSxpwrdZ's Avatar
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    It'll be pump limited before injector limited. Pressure will drop which will result in injector maxing out due to trying to compensate. A camshaft with proper fuel lobe will stretch the pump out quite a bit further which in turn will stretch out how far the injectors will go.

    FWIW rail pressure and injector timing are your friend!
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  9. #9
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    Quote Originally Posted by LSxpwrdZ View Post
    It'll be pump limited before injector limited. Pressure will drop which will result in injector maxing out due to trying to compensate. A camshaft with proper fuel lobe will stretch the pump out quite a bit further which in turn will stretch out how far the injectors will go.

    FWIW rail pressure and injector timing are your friend!
    Completely right! Also, making sure the low side is feeding that high side pump enough fuel is important too, always watch the low side pressure while logging!