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Thread: Determining safe timing limits ?

  1. #1
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    Default Determining safe timing limits ?

    Short of installing a cylinder pressure sensor and/or blowing up an engine, how does one determine the limit of safe timing advancement at various RPMs ?

    Is engine rattle a reliable indicator ?

    Are there any rules of thumb as a starting place ?

    Thanks

  2. #2
    Lifetime Member 2007 5.9's Avatar
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    I have a peak value that I use...which most would think is low...but I WILL NOT go over this value unless it's on a dyno..to verify that increasing timing over this value is necessary.

    My value is 25* overall. No pilot or post
    Les Szmidt
    2007 5.9 Dodge Ram
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    Lifetime Member DoghouseDiesel's Avatar
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    Like Les, said, without the truck on the dyno there are certain limits that I stay within.

    Some of those limits are determined by nozzles spray pattern, piston bowl design, engine RPM, piston clearance, etc....

    What is a limit on one truck, is not necessarily a limit on another truck.

    The limits I use on an '06 - '07 5.9 are NOT the limits I use on a 6.7.

    1207 HP / 1612 TQ

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    Lifetime Member 2007 5.9's Avatar
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    Agreed rich...my 6.7 numbers aren't the same as 5.9...didn't see the title area...
    Les Szmidt
    2007 5.9 Dodge Ram
    2014 Ram 3500 Aisin tuning Emissions Equipped
    EFI Live Cummins BETA Tester
    Silver Bullet Tuning
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    Quote Originally Posted by 2007 5.9 View Post
    I have a peak value that I use...which most would think is low...but I WILL NOT go over this value unless it's on a dyno..to verify that increasing timing over this value is necessary.

    My value is 25* overall. No pilot or post
    How does this change with a pilot shot ?

    What is the start of timing in EFI Live ?

    Is it where the main injection starts ? Or where the pilot starts ? And so if there is no pilot then its where the main injection starts ? Time to get out the oscilloscope ? :laughs:

    Thanks !

  6. #6
    Lifetime Member 2007 5.9's Avatar
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    Main is the basis for all timing...pilot is x degrees before main, and post 1 and post 2, are x degrees after main.

    All timing, pilot/post are referenced from main.
    Les Szmidt
    2007 5.9 Dodge Ram
    2014 Ram 3500 Aisin tuning Emissions Equipped
    EFI Live Cummins BETA Tester
    Silver Bullet Tuning
    silverbullettuning@gmail.com
    www.youtube.com/ljszmidt
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    25* at low RPMs is earlier than 25* at high RPMs because the injection ignition time is about the same but the piston is moving slower at low RPMs and fast at high RPMs.

    Are you accounting for that somehow ?

    I wasn't really looking for a fixed number, I was more looking for what the NON DESTRUCTIVE signs were or how people were arriving at what was good and what was bad.

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    Quote Originally Posted by 2007 5.9 View Post
    Main is the basis for all timing...pilot is x degrees before main, and post 1 and post 2, are x degrees after main.

    All timing, pilot/post are referenced from main.
    Are the post injections started relative to the start of main or from the end of main ?

    If you make the pilot long and close to the main, will the ECM allow it to run into the main, creating one long injection ?

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    Thanks for all of this, btw.

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    Quote Originally Posted by someguy View Post
    25* at low RPMs is earlier than 25* at high RPMs because the injection ignition time is about the same but the piston is moving slower at low RPMs and fast at high RPMs.

    Are you accounting for that somehow ?

    I wasn't really looking for a fixed number, I was more looking for what the NON DESTRUCTIVE signs were or how people were arriving at what was good and what was bad.
    One word to answer your question definitively...

    Dyno
    Les Szmidt
    2007 5.9 Dodge Ram
    2014 Ram 3500 Aisin tuning Emissions Equipped
    EFI Live Cummins BETA Tester
    Silver Bullet Tuning
    silverbullettuning@gmail.com
    www.youtube.com/ljszmidt
    http://www.facebook.com/SilverBulletTuninig

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