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Cylinder heads vary in design based on engine output and design. They are cast out of iron or aluminum.
BMW, for instance, builds a lot of performance design into its cylinder heads. Such systems as variable valve
timing (VVT) allow for on-the-fly valve timing adjustment based on engine demand. These systems are
electronically synced with engine performance systems and deliver high output. Overhead cam designs allow
the camshaft to be mounted directly on top of the head and make for a compact engine. Conventional engines
like those these V-8 heads belong to, have the cam mounted in the center of the engine and the heads only
housing the valves.