Balance is an important part of engine design and so this has also been included in this blog.
During manufacture, patterns that are the shape of the cylinder block are used to form a sand mould. Molten cast iron is then poured into the mould where it cools to become a rough casting of a cylinder block.
Before casting, the shapes of water-jackets, cylinders and some other parts are made up as sand cores. The cores are fitted into the moulds so that these parts of the block do not become solid cast iron during the casting process.
After casting, the core sand is removed through holes in the sides and ends of the block provided for this purpose. This leaves internal spaces for the water-
The lower section of the engine block forms the crankcase, and the part of the crankcase that extends below the main bearings is called the skirt. In some engines, the skirt is extended well below the centreline of the crankshaft and is called a full skirt. This is done to give the engine rigidity. Other engines have a very short skirt or none at all and rigidity is obtained in other ways.
Mono-block engines with cast-iron blocks have the cylinders bored directly in the cast iron casting. Cast iron is a suitable material for cylinders because it wears well and resists the effects of heat. Cylinder walls can be plated with chromium, which is very resistant to wear, although this is not common for passenger car engines.
The liners are cast iron sleeves that are either cast or pressed into the block. Liners that are cast into the block have grooves on the outside that form a key between the liner and the block. This prevents any possible movement and the sleeve becomes a permanent part of the block. (The cylinder blocks in
Aluminium alloy is used in the cylinder block to reduce the weight of the engine, but there is also an advantage that it is better at transferring heat than cast iron. The aluminium of the block has a similar expansion rate to the pistons.