What does DOHC on an engine mean?
2 Answers
DOHC on an engine refers to a Double Overhead Camshaft engine, where the intake and exhaust valves are arranged on two separate camshafts. The camshaft is a part of the engine's valve train, specifically responsible for driving the valves to open and close on time. Its functions are: 1. To ensure the engine draws in fresh combustible mixture into the cylinder at the right time during operation; 2. To promptly expel the exhaust gases after combustion from the cylinder. The camshaft directly drives the valves through rocker arms, making it suitable for high-speed car engines. The engine structure is relatively compact, ensuring intake and exhaust efficiency, simplifying the transmission mechanism, and reducing vibration and noise at high speeds.
DOHC stands for Double Overhead Camshaft, which directly controls the opening and closing timing of engine valves. I particularly admire the design concept of this structure—it adds an extra camshaft compared to the older SOHC (Single Overhead Camshaft) design, with one camshaft managing the intake valves and the other handling the exhaust valves. The advantage of this setup is that the camshafts are closer to the valves, allowing short rocker arms to directly actuate the valves, resulting in a more straightforward and efficient mechanical linkage. This enables the engine to rev higher and deliver smoother power output. Nowadays, performance-oriented vehicles, whether naturally aspirated or turbocharged, predominantly favor DOHC. Although the construction is more complex than a single camshaft and entails higher maintenance costs, it’s well worth it for cars prioritizing power response.
