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Thread: Pistons carbon buid up : tuning too rich at WOT ?

  1. #1

    Pistons carbon buid up : tuning too rich at WOT ?

    Guys,

    I'm in the process of installing my cam (TSP Stage 3).
    After removing the heads I found my pistons with significant carbon build up on them...I use my car mainly on roadcourse, hard mountain driving and AutoX. I previously had Headers, intake, Msd intake mani, ported TB and a tune I did myself (road and dyno). Car has 9300 miles.

    I was running a lambda between 0.86 (mid low rpm) to 0.84 (high rpm) because I found on the dyno it made more power this way.

    Looking at my pistons what do you think ? Should I run 0.88 as target after my cam is installed ?

    Or is it normal on the LT1 ??

    Which method will you recommed to clean that up ?

    0125202011~2.jpg

    Thanks
    Last edited by Sachs; 01-27-2020 at 01:56 PM.

  2. #2
    Senior Tuner Ben Charles's Avatar
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    If you are boosted that’s about right!! NA that’s too rich from what I have found makes the best power

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  3. #3
    Tuning Addict 5FDP's Avatar
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    Switch to E85, it'll clean that stuff right up lol.
    2016 Silverado CCSB 5.3/6L80e, not as slow but still heavy.

    If you don't post your tune and logs when you have questions you aren't helping yourself.

  4. #4
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    What did the backside of the valves look like? Something seen quite often was guide clearance issues causing oil burn - top of the one piston looks like oil buildup instead of carbon from fuel....
    2010 Vette Stock Bottom LS3 - LS2 APS Twin Turbo Kit, Trick Flow Heads and Custom Cam - 12psi - 714rwhp and 820rwtq / 100hp Nitrous Shot starting at 3000 rpms - 948rwhp and 1044rwtq still on 93
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  5. #5
    Quote Originally Posted by GHuggins View Post
    What did the backside of the valves look like? Something seen quite often was guide clearance issues causing oil burn - top of the one piston looks like oil buildup instead of carbon from fuel....
    Not too bad for what I see. Some build up, but fairly small. Should put an oil catch can though..I'll know more when I remove the valves to do the springs swap/valve guides etc..

  6. #6
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    I'd install a catch can and lean it out a bit to .87/.88
    2023 Ford Maverick 2.0T AWD

  7. #7
    Advanced Tuner
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    What vehicle is this from? carbon fouling or "coking" as they call it is normal on the newer DI GM vehicles.

  8. #8
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    Looks normal. A catch can would help a lot. So will switching to Ethanol. Also, you should be able to run .88 lambda without an issue
    2009.5 PBM G8 GXP M6 W/Roof-Self tune, OBX LTs, Kooks axleback, LSA blower, cam,
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  9. #9
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    Quote Originally Posted by Sachs View Post
    Guys,

    I'm in the process of installing my cam (TSP Stage 3).
    After removing the heads I found my pistons with significant carbon build up on them...I use my car mainly on roadcourse, hard mountain driving and AutoX. I previously had Headers, intake, Msd intake mani, ported TB and a tune I did myself (road and dyno). Car has 9300 miles.

    I was running a lambda between 0.86 (mid low rpm) to 0.84 (high rpm) because I found on the dyno it made more power this way.

    Looking at my pistons what do you think ? Should I run 0.88 as target after my cam is installed ?

    Or is it normal on the LT1 ??

    Which method will you recommend to clean that up ?

    0125202011~2.jpg

    Thanks
    I think your right on point, all my dyno tuning agrees with your findings, best torque and horsepower at .86.

    I think a catch can is the more likely fix.

    Ted.

  10. #10
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    My L86 with 120K was not tuned as far as I know it except I put a E85 sensor on it and enabled it with HP tuner about 5,000 miles before this picture. I bought it with 105K. It hurt lifter so I swap out the cam to a TSP stage two 218/225. It looked similar to yours.


    I can?t get my phone to post the picture, I post it from my work computer tomorrow

  11. #11
    Senior Tuner mbray01's Avatar
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    I think a better question is how do you drive it. In my experience pistons that look like that tend to be from people who drive moderately, and only occasionally bury their foot in the throttle. If you drive it like you stole it, they rarely look like that, even waaaay over fueled, they will be black but rarely have build up like that
    Michael Bray
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  12. #12
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    Here is my L86. I have no idea how it was driven before me.

    But

    look at MPG averages on the dash which where 4 mpg better than I get. They drove it with a much lighter foot than me LOL. And it was in perfect shape.

    IMG_0824.jpg