Engine block

Block of a modern V6 diesel engine. The large holes are the cylinders, the small round orifices are mounting holes, and the small oval orifices adjacent to the cylinders are coolant or oil ducts.

In an internal combustion engine, the engine block is the structure which contains the cylinders and other components. In an early automotive engine, the engine block consisted of just the cylinder block, to which a separate crankcase was attached. Modern engine blocks typically have the crankcase integrated with the cylinder block as a single component. Engine blocks often also include elements such as coolant passages and oil galleries.

The term "cylinder block" is often used interchangeably with "engine block", although technically, the block of a modern engine (i.e. multiple cylinders integrated with another component) would be classified as a monobloc.