h392ncp 30 piston opinions

Discussion in 'The Bench' started by Jeremy Zepnick, Nov 25, 2021.

  1. Anyone have their opinion on h392ncp 30 pistons?
    Using with a TA 413 cam.

    Would be greatly appreciated, thanks in advance
  2. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD" Staff Member


    1.985 compression height.

    3.90/2 + 6.6 + 1.985 = 10.535". Stock deck height is 10.570". 10.570 - 10.535 = .035"

    So these pistons will theoretically be .035" in the hole.

    23cc valve reliefs/dish is good to build compression.

    Hypereutectic pistons are less tolerant of detonation, so ignition timing has to be right to avoid engine damage.

    With typical 71cc chambers and .040 head gasket, about 9.4:1 static compression,

    dan zepnick likes this.
  3. dan zepnick

    dan zepnick Well-Known Member

    Would like to know what compression would be with .020 steel shim head gaskets??
  4. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD" Staff Member


    I'm guessing somewhat on the combustion chamber cc's and the deck height. You would need to measure that to confirm, but this gives you an idea.
    dan zepnick likes this.
  5. Jim Weise

    Jim Weise EFI/DIS 482

    My opinion?

    I would not use them if you gave them to me. Even with all the right clearances and end gaps, these pistons are considerably more brittle than the factory cast pistons.

    If your on a budget, use aftermarket or good stock/nos cast pistons

    If the budget allows, use the TRW forged pistons or better.

    Pistons are not a place to save money.

    Too many horror stories of a bad tank of gas, or a stuck thermostat, causing a little detonation, and then boom.. a piston shatters, and sends the shrapnel thru the engine via the intake.

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  6. Thanks! I'm heading to Ohio today to pick up a motor and it has those pistons.
  7. It's home!

    Attached Files:

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