Just head over to the LS1tech.com website and search cracked aluminum blocks, there are a few BS post in there but a few others that are talking about their block cracking and if they should JB weld it etc etc etc. I'm not sure why you find it hard to beleive that any engine with enough load and power will crack. Why is it so much harder to believe that the softer aluminum metal can crack if under too much pressure?? Its like youre trying to argue that the sky is blue 100% of the time in vegas and it will never rain.

PLAIN AND SIMPLE ALL BLOCKS CRACK UNDER EXTREME PRESSURES, TEMPS, AND LOAD. Softer metal has a tendacy to crack or warp sooner then harder metals. Have you ever heard of a warped head?? Have you heard of a warped iron head?? Metal warps guys no matter how you slice it. If not then blocks would never have an issue other than internals. I've seen personally cracked main journals, infact my bottom end came out of a cracked block. The guy went to build it and didnt realize it was crack until he seated the the crank into the main journal then gave up. Sold the whole setup to me and i used an iron 5.3l block, bored it to 3.903 noched the block and put in a 4.000" crank with 6.25 rods in there -30cc dished pistons.