What is DOHC?
3 Answers
DOHC (Double Overhead Camshaft) refers to dual overhead camshafts in Chinese. More details about dual overhead camshafts are as follows: 1. Function: Dual camshafts can adjust valve overlap angle, thereby delivering greater horsepower. However, they tend to produce insufficient torque at low RPMs and may pose certain maintenance difficulties due to their complex mechanical structure. 2. Origin: The dual camshaft technology originates from racing cars, primarily designed to control the timing difference between intake and exhaust valves.
DOHC stands for Double Overhead Camshaft, which in automotive engines means there are two separate camshafts mounted on the cylinder head—one controlling the intake valves and the other managing the exhaust valves. This design allows the engine to operate more smoothly at high RPMs due to precise valve timing control, enhancing power response and fuel efficiency. Many performance cars utilize this setup, such as the Honda Civic's engine, which delivers strong acceleration and quiet operation, outperforming the single-camshaft SOHC design. However, to fully leverage its advantages, it needs to be paired with variable valve timing technology, like Toyota's VVT-i, ensuring stable RPMs at high speeds and ample low-end torque. It also improves daily driving experiences with prompt starts, though the structure is more complex, yet overall reliability remains high.
Speaking of DOHC, it represents a major evolution in automotive engineering history, evolving from the early days of overhead camshafts to becoming a standard feature in modern engines. Why? Because it solves the challenges of multi-valve designs, such as when a four-cylinder engine with four valves can't be efficiently managed by a single camshaft. The dual overhead layout precisely controls the opening and closing of each valve, reducing vibration and noise, making it especially suitable for high-speed scenarios. Most sports cars and performance models favor it, as it delivers stronger power when paired with turbocharging. However, don’t forget about maintenance—timing chains need regular checks to avoid breakdowns that could delay your drive. I’ve personally driven a car with DOHC, and during highway cruising, the engine sound is smooth and fuel-efficient.
