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Piston / Connecting Rod Question

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  • Piston / Connecting Rod Question

    Bad news today............... I was driving the other night on the way home from dinner and I noticed a slight miss in the car's idle. It felt like a dead hole. When I got home, I let it idle and it was very rich. Checked plug wires etc.. and thought well I may have a Mass Air problem.

    Checked the car out today and found #2 hole with no compression. Blow-by out the valve cover and then just tonight to confirm my fears ....... knocking (loudly). Dead piston for sure.

    Question for those who have rebuilt the bottom end is.........

    I am going to have to buy pistons (preferably forged), do you really think I need to upgrade the connecting rods as well? The car is a 9:1-NA motor that I plan on installing forged turbo pistons into. I know the turbo rods are forged but what about the NA rods?
    Finally does anyone have a good source for pistons?
    1970 240Z

    88 Shiro Special (SS)
    185 RWHP
    205 RWTQ

    88NA2Turbo w/
    311 RWHP
    393 RWTQ
    If you BOOST it ........ it will run!!!!!!!!!!!

  • #2
    All Z rods are forged. From the 240Z to the 350Z...

    As for pistons. There are 3 options:

    Rebuild with stock cast pistons. Stockers are good for around 400+ hp but I personally wouldn't want to run anymore than 400hp on a cast piston.

    There are really few off the shelf pistons for the Z31 anymore. That is assuming you can even find them. You'd have to contact a shop like Wiesco or Ross about making you custom pistons.

    3rd option is to go with Z32 rods and Z32 pistons. Easily found and for a decent price. Only down side is the compression ratio advertised will be about a point lower.
    Example: 9:1 Z32 pistons would be 8:1 in a Z31 engine. ... 85a6df856&

    It really just comes down to how much power you want and how much you can afford to spend in getting there.