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.

It can be cast in one piece from grey iron.

Or it can be alloyed with other metals like nickel or chromium.

The iron casting process begins by making up the shapes of what will become waterjackets and cylinders as sand cores which are fitted into moulds. This stops these parts becoming solid iron during casting.

Molten iron is poured into sand moulds that are formed by patterns in the shape of the block.

After casting, core sand is removed through holes in the sides and ends, leaving spaces for the cooling and lubricant passages. These holes are sealed with core or welsh plugs. The casting is then machined. Cylinders are bored and finished, surfaces smoothed, holes drilled and threads cut.

All cylinder blocks are made with ribs, webs and fillets to provide rigidity but also keep weight to a minimum.