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Drilling and tapping a block for bigger head fasteners...

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  • #16
    Don't forget the shrapnel shield.



    Originally posted by RacinNdrummin View Post
    350cc of fuel to 4000rpm

    ~105lb/min of Airflow

    ~50psi of boost pressure

    Shooting for 600-700 horsepower at the wheels with a 3400rpm horsepower peak, and about 1300lb-ft of torque at 2600RPM...

    8 cylinder Bosch P7100 injection pump
    16:1 compression
    94 IDIT connecting rods
    Main Girdle/Studs
    BW 60/68/.91 and 75/96/1.32 Turbochargers
    Block Deck will be O-ringed
    Paul A.
    SE Texas

    Make it fit.
    You can't win and there is a penalty for trying!

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    • #17
      Originally posted by strokersix View Post
      As you say, more clamp force is required to withstand the applied loading. However: Did you study joint diagrams? Increasing fastener diameter should be accompanied by increased fastener length for a robust connection. If you have room, stout hardened standoff bushings (like 1 inch tall) to increase fastener stretch would help a lot. If there is enough meat in the bottom of the block you may be able to counterbore and tap deeper to increase the fastener grip length (and amount of stretch) as well.

      If you don't believe or understand what I'm trying to tell you, boltscience.com has some good basic info.
      I understand what you are saying but I simply don't have the room. I tried drilling the test block .875" deeper (7.000" studs vs. 6.125" studs, 7" is how long the 7.3 studs are) and I got a broken boss because the casting necks down at that point. Also, the rocker arms are directly over the top of certain studs, so I am limited by how much I can space the nuts up as well.

      Literally the only way of achieving the clamp load I want is using these studs, I have already done a bunch of experimenting, the stud isn't the issue, its the meat to hold it in place. 8740 190Kpsi studs have the right amount of clamp load I need.
      Justin Anderson
      Fortynine Industries

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      • #18
        Originally posted by Paul Alciatore View Post
        Don't forget the shrapnel shield.
        Lol, its not out of the realm of structure of this platform..... At least yet....This will set the ceiling, or set a new benchmark, one of the two.
        Justin Anderson
        Fortynine Industries

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        • #19
          I wasn't joking. It sounds to me like you are going a fair amount beyond the known good envelope and a catastrophic failure is a definite possibility.

          I mean, I am sure the original engineers who designed this engine were under the well known restraints of performance vs. cost. I am sure they included or at least thought they included a certain safety factor. But you are shaving away some of that factor so now it is reduced or perhaps even non existent. Now, add one small defect in the casting, near one of your new studs/bolts. A void, an inclusion, a small crack, whatever. The original safety margin would have taken care of it. But now ..... shrapnel?

          I'm just saying to use some care.
          Paul A.
          SE Texas

          Make it fit.
          You can't win and there is a penalty for trying!

          Comment


          • #20
            The larger the firecracker, the higher the tin can goes.

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