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Thread: 04 Cummins Street tune. Timing

  1. #1

    04 Cummins Street tune. Timing

    I am having trouble building my timing table for a street tune. I have stock internals a cold air intake 5 inch straight pipe and it's a nv5600. I had good results with a near stock timing table but I have big power plans in the future and need to understand how to make a good timing table and what makes quick acceleration. After completely retarding the table and completely advancing it. Both provided slower results than my stock table. I understand timing but not how to make a table that uses it effectively to make power.

  2. #2
    The 03-04 Timing Curve is pretty well optimized for response and drivability on that piston design compared to the later generations which were neutered for emissions standards.

    The newest diesel stuff is running about 90% BTDC for timing targets while under load, which is significantly more aggressive than what we had seen years ago with a common "50/50" split; which I personally never liked.

    As with anything, timing and "Target % Before TDC" needs to vary with load and RPM to truly make sense.

    A curve shaped something like this works well for these engines on "Steady State": Screenshot 2025-05-04 004643.png

    For this piston design I normally keep the Transient timing alone, although this shape is safe enough to not cause misfires if copied over to there as well.

    To be frank, as a professional EFI tuner, coming to diesel was an eye opener on so many things. It's so simple, yet so complex at the same time as we are purely controlling fuel timing and quantities to really optimize these things. It's not an easy task to identify what a diesel engine wants without getting yourself into some trouble.

  3. #3
    Thanks for the lengthy helpful right up. I went back to a almost stock table and had amazing results with my tune for power. I might try and leverage retarded timing for quicker spool but for the most part just adding a degree of timing in my power RPMs it made a huge difference. Personally I've never tuned any gas engines but it's definitely a whole other can of worms tuning a diesel. This is my first experience with any tuning so I'm still learning a lot but Im very happy with my results so far.