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Thread: L76 VVT Tuning Pointers

  1. #1

    L76 VVT Tuning Pointers

    I have an 07 Silverado VMax with the L76, that is my personal vehicle. I've done a complete tune on it and it runs great, but the VVT is intriguing to me. I've never messed with that stuff before, but I understand the basics of advancing and retarding the camshaft. And, if I've read correctly the cam phaser has a 52* range of influence, is that correct? It seems like I could make substantial gains by tweaking the tables. But I'm afraid I'll screw something up. Does anyone have any advice or pointers? They would be much appreciated!

  2. #2
    Tuner in Training Longslyde's Avatar
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    I've worked with the settings in this area and found that the factory settings are about as good as it gets with a stock cam if that is what you are running. YMMV. The only area that I found some improvement was in the idle/cruise rpm area where GM plays with the cam settings to reduce pumping loss (for economy) and create an EGR effect (for emissions). I had to zero this area out as I was having a problem with low vacuum at cruise and it was causing problems with boost actuation and spark knock. After zero the lower rpm areas, it was much more responsive in that range and manifold vacuum raised by about 4-5 inches, which, in my case, made the supercharger function as intended. I wouldn't mess with the upper end of the tables, I think GM actually had those pretty accurate for the stock cam. Remember, If you change the cam timing in a given range, you have to adjust timing and airflow to find out the benefits or downfalls of that setting.

    I do believe there are some substantial gains to be had with an aftermarket cam though if proper tuning procedures are followed. The mistake I see peple making is that they are only changing the setting for cam position and not adjusting the other parameters that go with that. In which case, it will not perform well or as well as it could. I believe this exact scenario is what makes people take the VVT out of the engine thinking that a non-VVT engine performs better.
    Tak care!
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  3. #3
    so did you just place zeros in the low load areas up to around 2400 rpm?

  4. #4
    Quote Originally Posted by Longslyde View Post
    I've worked with the settings in this area and found that the factory settings are about as good as it gets with a stock cam if that is what you are running. YMMV. The only area that I found some improvement was in the idle/cruise rpm area where GM plays with the cam settings to reduce pumping loss (for economy) and create an EGR effect (for emissions). I had to zero this area out as I was having a problem with low vacuum at cruise and it was causing problems with boost actuation and spark knock. After zero the lower rpm areas, it was much more responsive in that range and manifold vacuum raised by about 4-5 inches, which, in my case, made the supercharger function as intended. I wouldn't mess with the upper end of the tables, I think GM actually had those pretty accurate for the stock cam. Remember, If you change the cam timing in a given range, you have to adjust timing and airflow to find out the benefits or downfalls of that setting.

    I do believe there are some substantial gains to be had with an aftermarket cam though if proper tuning procedures are followed. The mistake I see peple making is that they are only changing the setting for cam position and not adjusting the other parameters that go with that. In which case, it will not perform well or as well as it could. I believe this exact scenario is what makes people take the VVT out of the engine thinking that a non-VVT engine performs better.
    Tak care!
    Absolutely correct and now that the weather is good enough to drive my L92/t56 swap car again? We're working on this..... I dont know if I'll have more info to publish or not as Im working with a local tuner whos job is to tune so if he doesnt want me to talk about it.... I wont. But the key point here is indeed what I highlighted in bold above. I see a lot of shops recommending ditching VVT for all sorts of claims that are just unfounded. Even with my own hacked up tune this thing FLIES compared to my LS1 in there before.

  5. #5
    Advanced Tuner
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    Exactly! There is more to it than just the advance tables.

    Do a search. There is a thread on here somewhere where I posted a bunch of info on how the VVT works, on the different motors.


    The only negative with the VVT motors, is if it's not done right, and motor is turned high RPM, the valves can hit the pistons. Mostly because the valve springs aren't heavy enough, but I'm sure some of it has to do with the tuning as well....

    And don't forget VVT spark timing also!

  6. #6
    Tuner tiresmokinV8's Avatar
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    What do we do with the spark timing? I have an aftermarket tsp vvt cam and they sent what to set the vvt phaser timing tables to but said nothing about the vvt spark timing.
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  7. #7
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    Quote Originally Posted by tiresmokinV8 View Post
    What do we do with the spark timing? I have an aftermarket tsp vvt cam and they sent what to set the vvt phaser timing tables to but said nothing about the vvt spark timing.
    When you change valve timing, you also need to change spark timing. There just happens to be three matching tables in the tune ..They will add/subtract from the main spark tables.