I have never seen a block broken on its own. Take all the rotating assembly failures out and no never seen one. I’m not sure you can take all the rotating failures out though, if the caps walk because the block is moving and takes a bearing out isn’t the block “failing”
Yes. That means the block was seeing more load than it could handle.
Again, the only question this really answers is how long did it take you to FIND the crack. If you went 100 runs and found the crack, did it happen on run 99? Nope. Sure didn't. That fracture started long before it was found.
I say these cracks show up very early and then just keep growing until the expose an issue.
So no one really knows how many runs before a fracture happens. Same when you mag a crank, or rods.
