After looking at it more today there is a very tiny hair line crack the rest of the way up. but it only broke through in the bottom. I don't see how number 2 cylinder would be the only one to take a hit if the block twisted. It's a .020 over bore so 86.5bore. motor has been running 30psi for the past 9 months. put c16 in and turned it up to 36psi and it let go.Looks like it's cracked all the way down the cylinder? Judging by all the green anti-freeze it's not been frozen, maybe block twist? has it been bored out? what boost has it been running?