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  • #1

    Minimum cylinder thickness

    We are in the process of building a 430+ CID small block and I am wondering what the thinnest cylinder wall thickness you would run in both the thrust direction and 90 deg to trust? We plan on filling the block at least half way up with hard block and still run it on the street.

    Thanks
    Mike
    Tags: None
  • #2
    Re: Minimum cylinder thickness

    What block???? Mopar or Chevy Mike? LOL
    2007 SBN/A Drag Week Winner & First only SBN/A Car in the 9's Till 2012
    First to run in the .90s .80s and .70's in SBN/A
    2012 SSBN/A Drag Week Winner First in the 9.60's/ 9.67 @ 139 1.42 60'
    2013 SSBN/A Drag Week, Lets quit sand bagging, and let it rip!

    Comment

    • #3
      Re: Minimum cylinder thickness

      R3 small mopar. We plan on putting a 4.25 " crank in.

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      • #4
        Re: Minimum cylinder thickness

        Stupid ?? Mike.Is that a siamese block?

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        • #5
          Re: Minimum cylinder thickness

          No it the block Bob has.

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          • #6
            Re: Minimum cylinder thickness

            .200 is a min after overbore on the thrust side, from what I have been told, that's why I don't think I will be going .040 over with my 400 block you might get by with less if it does not detonate and has a long rod in it. Morton is going to sonic check it but I don't think it will go again I know some 400s have had as little as .070 where they crack.
            2007 SBN/A Drag Week Winner & First only SBN/A Car in the 9's Till 2012
            First to run in the .90s .80s and .70's in SBN/A
            2012 SSBN/A Drag Week Winner First in the 9.60's/ 9.67 @ 139 1.42 60'
            2013 SSBN/A Drag Week, Lets quit sand bagging, and let it rip!

            Comment

            • #7
              Re: Minimum cylinder thickness

              150 thou minimum on the non thrust sides.

              I like to see over 200 thou if its going to be a stroker with high piston speeds, or nitrous motors. They will flex the bore more.

              Comment

              • #8
                Re: Minimum cylinder thickness

                Greetings, All,

                There are no generalities in cylinder wall thickness recommendations. Two factor should be mentioned:

                1. Deck height. The longer the cylinder, the thicker it has to be to maintain sufficient stiffness to resist cracking, The SBF is so short, it can get by with .150". The BBM is so tall, 150" is not enough in high pressure situations.
                2. Diameter. The larger the diameter, the thicker the cylinder wall should be. Take a siamesed-bore BBC out to max diameter. Put it on a power hone and put a cylinder bore gauge in the cylinder adjacent to the one being honed. As the hone strokes the bore gauge will measure significant distortion in the adjacent cylinder. It is amazing to me that the piston rings of today and the tiny strip of iron remaining between the cylinders will seal 1000+hp when the cylinder walls feel like a beer can with a firecracker inside it. A tribute to modern ring and gasket technology.

                Bottom line, more cylinder wall thickness is better investment than that last fraction of bore diameter. I once sleeved a 455" Pontiac back to STD bore and made more horsepower than the previous builder made with a .060" overbore.

                thnx, jack vines

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