The block is metal block that contains the cylinders. There are no aftermarket blocks made for the Z (Zima block is the same as the Z32 block). However when people say "The block is stock" like how this guy referred to his car as in the email they're talking about everything in the motor... pistons, rods, bearings, etc are all stock. "stock block" means no internal work...and that's what this guy is claiming... 1100 HP with no internal work ain't gonna happen on a Z.