What is a cylinder head anyway?
The cylinder head closes the combustion chamber of an internal combustion engine upwards. In all modern four-stroke engines, the cylinder head houses the inlet and outlet ducts and the valve control for gas change, oil ducts, the lubrication of the valve train and, in the case of water-cooled engines, coolant ducts. In petrol engines, the cylinder head also contains the spark plugs and in petrol direct sprays the injection valves.
Due to the complicated manufacturing process, the cylinder head is one of the most complex and expensive parts of a vehicle alongside the engine block.