The cylinder block is the largest part of the engine. Its upper section carries the cylinders and pistons. Normally, the lower section forms the crankcase, and supports the crankshaft.
Cylinder blocks made of aluminum are lighter than cast-iron blocks of the same size. They usually have cast-iron liners which provide a hard-wearing surface for pistons and piston rings.
A dry sleeve can be cast or pressed into a new block or used to recondition cylinders. A flanged, dry sleeve has a flange to fit a recess in the block. A wet sleeve has an outer surface directly exposed to coolant.
