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  1. #1

    Leakdown & GIO Revisited

    With 4 or 5 addtl hours on new engine, leakdown test results went from 10, 10, 15, 20 to 8, 8, 10 and 15.

    Is this a significant improvement? If so, is it explained by anything other than improved piston ring seal?

    Also, might GIO be partially influenced by air and water temps? I know all about the venting issues and fixes, but I'm just wondering whether this particular engine may run different when consistently operated at water temps below 50 and air temps 30 to 60.

    I know these temps are not extreme, but are they below ideal ranges for top performance of this particular SC engine?

    When intercooler is clean, my ski runs like a beast even in hail but I'm trying to understand the whole picture.

  2. #2
    kman's Avatar
    Join Date
    Aug 2007
    Are you doing the leakdown test yourself? When I did mine I had some bad numbers and could hear air escaping out the exhaust. I had to remove the valve cover and tap on the exhaust valves to seal them before I got consistent numbers. Maybe the improvement you are seeing is just the fact that the valves were seated better at the time???

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