Went racing last weekend. Lost 2nd round -.003 red so I got back to the trailer and was going to drain the water because they're calling for low 30's at night this week and I don't want to crack the block. I took the radiator cap off and I notice the radiator is low. I look around and everything looks dry externally so I pull the dipstick and the oil looks milky. I started checking it out and I found water in #5 cylinder when I removed the spark plugs but it was also pushing out of the oil pan drain hole when I pressurized the cooling system. Suspecting a head gasket problem or a cracked cylinder wall I pulled the head off. The gasket looked good so I checked the cylinder. There was rust in the cylinder so I wiped it with WD-40 and started looking. I saw what looked like pitting so I took a pick and most of the spots were just spots then I found a pinhole in the side of the cylinder. I'm going to pull the engine this weekend and hopefully get it disassembled and pop the freeze plugs out so I can look for other possible problems. I assume it rusted from the back side of the cylinder so I don't know how much I'll be able to see. I will probably have it sonic tested and them hopefully I can just have it sleeved so I don't need to have another block completely done. I've never seen or heard of this happening. I wanted to let others know what I found and I was wondering if anyone else has experienced this before?