The main engine casting which contains the cylinders, crankshaft and pistons.

See engine block.

The main structural member of an engine in which is found the cylinders, crankshaft and other principal parts.

The basic part of the engine to which other engine parts are attached. It is usually a casting and includes engine cylinders and the upper part of the crankcase.

The cylinder block or engine block is a machined casting (or sometimes an assembly of modules) containing cylindrically bored holes for the pistons of a multi-cylinder reciprocating internal combustion engine, or for a similarly constructed device such as a pump. It is a complicated part at the heart of an engine, with adaptions to attach the cylinder head, crankcase, engine mounts, drive housing and engine ancillaries, with passages for coolants and lubricants. The distance between the cylinder bores (midpoint to midpoint) cannot easily be changed since the machining facilities would require extensive modification.