What is a DOHC engine?
4 Answers
DOHC engine stands for Double Overhead Camshaft engine, where the intake and exhaust valves are arranged on two separate camshafts. Advantages include: higher performance, better stability, lower noise levels. Due to the complex manufacturing process, the cost is higher. Multi-valve engines allow for more complete combustion, enabling more fresh air to enter the engine, resulting in better emission efficiency. Additional information: 1. DOHC engines generally have higher torque and power compared to regular engines. The pistons are also different from those in conventional engines, as they need to be stronger to maintain normal engine operation. 2. The function of the camshaft is to mechanically coordinate the opening and closing actions of the intake and exhaust valves. SOHC refers to the situation where a single camshaft completes the opening and closing actions for both intake and exhaust valves, while DOHC uses two separate camshafts to independently control the intake and exhaust valves for their respective opening and closing actions.
A DOHC engine is one equipped with two camshafts, specifically responsible for valve operation. The camshafts are mounted at the top of the engine, with one managing the intake valves and the other controlling the exhaust valves, making it far more efficient than a single camshaft setup. This allows for more precise valve timing, ensuring smoother engine breathing at high RPMs, delivering stronger power output when the throttle is pressed, and even contributing to slightly better fuel efficiency. Most modern passenger cars now use this configuration, with iconic engines like Honda's VTEC being based on DOHC architecture—though they do have more components, making maintenance slightly costlier. For daily driving, it's important to pay attention to oil quality and adhere to timing belt replacement schedules, as this design remains quite user-friendly for regular use.
I specifically researched DOHC when choosing a car, and its biggest advantage is the fast power response. The two camshafts have clear division of labor, allowing more precise valve control. It's fuel-efficient at low RPMs and delivers strong acceleration at high RPMs, especially when overtaking on highways. Nowadays, it's quite common to see small-displacement turbocharged cars equipped with DOHC. Although it's more complex than the old single camshaft design, the technology is mature with low failure rates. For maintenance, just remember to check the timing chain at 60,000 kilometers. Overall, its performance is significantly better than SOHC.
DOHC stands for Double Overhead Camshaft, where the intake and exhaust valves are controlled by two separate camshafts. Simply put, it's like two rods pushing open the valves, offering faster and more precise response compared to a single camshaft. The effect becomes more noticeable as the engine revs higher, with power output typically about 10% greater than a single camshaft design. The downside is slightly more complex machinery, though repairs aren't particularly difficult. Many new cars now use this basic structure, and when combined with variable valve timing, it becomes VVT technology. When driving, you'll notice especially smooth acceleration with just a light tap on the throttle - that's its advantage.
