replacing the stock camshafts in single and double overhead cam (SOHC and DOHC) engines is a simpler task than with the centrally-located camshafts in pushrod engines. An engine's camshaft has egg ...

A key design feature of the new platform is a Double-Overhead-Camshaft (DOHC) realizing significant advances in combustion and thermal efficiency. Friction losses across the engine design have ...

leading to the invention of the 4-valve per cylinder double overhead cam. Past four-valve-per-cylinder engines had issues with their low-end torque being traded for high-end power and vice versa.