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  1. Fingers

    Cracked Piston

    Video https://youtu.be/o1lloyhPJFI https://youtu.be/tq5Le6laeyQ
  2. Fingers

    Cracked Piston

    Pin clearances are good. Hard pack indications are only on the top of the pin bore from the obviously significant chamber pressures. Pattern is even. Bottom half of pin bore shows normal/minor wear. No indication of binding. As you can see in the picture, the crack is only half way across the...
  3. Fingers

    Cracked Piston

    There could be several causes of the oil not cooling the pistons. Considering it was a drag truck, it could have starved the pickup at launch or even overloaded the top end with oil. Internal wind in the crank case could have blown the squirters off their mark. (not likely) All of the pistons...
  4. Fingers

    Cracked Piston

    Well, it finally happened. Although it was preventable. Two Cast Oval Bowls cracked in a full on race build running well over 1000 HP. The cracks are on the outside of the piston and run from the pin boss up through the steel ring land. Most likely caused by ring stress from loss or reduction of...
  5. Fingers

    Billet Pans now at Limitless Diesel

    Just think how many chips gave up there existence for that pan to come to life!
  6. Fingers

    LMM: LMM with 222,000 tear down rebuild

    Some of the cover plate bolts get close, if not into the water jacket on the block. Did any of the bolts have coolant residue on their threads?
  7. Fingers

    LMM: LMM with 222,000 tear down rebuild

    Looks like it leaked between the cross over to the bolt holes then out from under the heads of the bolts.
  8. Fingers

    LML Piston protrusion/head gasket...

    Very hard to tell from the injector marks. They are made as the piston is already on the way down. Dude, that piston pitting at the top is usually an indication of water in the cylinder. (steam pitting)
  9. Fingers

    LML Piston protrusion/head gasket...

    Maybe some, but it is mostly because the pistons run much cooler than stock. Keep in mind the available quench area on a piston with valve reliefs is very small.. The exposed area on the top of the oval piston has a significantly smaller area and thus absorb and impart less heat to/from the air...
  10. Fingers

    LML Piston protrusion/head gasket...

    Very small distances between the metal surfaces in the chamber cause "quench". That is, they snuff out the combustion in that area by drawing off the heat in the air/fuel charge below the combustion threshold. This creates a dead charge. Minimizing the volume in the quench zones improves economy...
  11. Fingers

    Duramax build and the machine shop.

    Longevity of the pistons would not have been an issue with the Ovals, though the blow by can get high with the higher compression. (18:1 and higher) I sell the gapless second rings now to keep that in check, but that seems to be a big limiting factor in getting anything good out of the higher...
  12. Fingers

    Duramax build and the machine shop.

    Who Quoted you those Prices for my pistons? Way out of line. Jon
  13. Fingers

    Injector Spray Pattern - LMM

    Once the piston cracks into the oil gallery, the engine oil itself burns like a super hot torch destroying the piston more. Small cracks turn into big holes fast.
  14. Fingers

    Injector Spray Pattern - LMM

    I don't want to completely discount cooling as a factor. Specifically, shock cooling/heating. Keeping the engine/pistons cool is a good thing and should reduce the shock swing on the pistons. However, cracking on rapid load application is an indication the the core of the piston is cool while...
  15. Fingers

    Injector Spray Pattern - LMM

    Marine applications are bastards for thermal shocking all engine parts. Blocks and heads too. I thought you had run some Oval Bowls.... The main problem has to do with pressurization of the area above the fire ring. Think of a fire cracker in a paper cup and how it splits. If that area...
  16. Fingers

    Injector Spray Pattern - LMM

    No, the silica does not cause the problem. It enhances the thermal stability of the aluminum, but does reduce the ultimate strength. In other words, it helps control the thermal expansion of the piston. Oil cooling does help keep the pistons cooler. But they are not melting, they are cracking.
  17. Fingers

    Injector Spray Pattern - LMM

    The problem with pistons cracking is not a cooling issue.
  18. Fingers

    How to stop the Smoke

    Disconnect the pipe from the turbo and cobble an adapter to pressurize the intake system from the turbo through the intercooler to the manifold.
  19. Fingers

    How to stop the Smoke

    Yes, but how much depends on the cam. The hotter the cam, the more critical the cam timing.
  20. Fingers

    How to stop the Smoke

    What you get for a compression reading depends greatly on the rig you use to take the reading. The biggest thing you get is cylinder to cylinder comparisons. If you're lucky, you can compare readings over time with the same rig. 16.5 actually produces over 600 PSI in the chamber, but the volume...
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