I did crack a Ford 289 block like the above picture. It was a throw together motor for my old Ranger I had while I was building the good one for it. Was beyond out of balance. Truck spun 3600 or so rpm on the freeway. Does not take much of an imagination to figure out why it happened, but it did run several thousand miles, a good portion of it with the go pedal in the floor board off roading.....