The DOHC16V engine is a double overhead camshaft engine, where 16V indicates that the engine has a total of 16 valves, providing greater torque and power compared to a standard engine. For engines of the same displacement, those with more valves generally perform better. To enhance intake and exhaust efficiency, multi-valve technology is commonly used today, typically featuring 4 valves per cylinder, totaling 16 valves for a 4-cylinder engine. There is also an SOHC (single overhead camshaft) engine, which is used for a single-valve structure. In a DOHC engine, the intake and exhaust valves are arranged on separate camshafts, offering advantages such as higher mobility, better stability, and lower noise levels. Multi-valve engines allow for more complete combustion by enabling more fresh air to enter the engine, resulting in better emission efficiency. Additionally, the pistons in a DOHC engine differ from those in a standard engine, as DOHC engines require more robust pistons to maintain normal operation. From the working principle of an engine, it is understood that an engine generally completes a working cycle consisting of four stages: intake, compression, combustion, and exhaust. For the cylinder to intake and exhaust air, it requires intake and exhaust valves. The camshaft mechanically coordinates the opening and closing actions of these valves. SOHC refers to a system where a single camshaft controls both the intake and exhaust valves, while DOHC uses two separate camshafts for the intake and exhaust valves. Valves are responsible for introducing air into the engine and expelling exhaust gases after combustion. Structurally, they are divided into intake and exhaust valves. The intake valve draws air into the engine to mix with fuel for combustion, while the exhaust valve expels the burnt gases and dissipates heat. Traditional engines feature one intake and one exhaust valve per cylinder, which simplifies the design. A single camshaft controls both valves, resulting in fixed valve timing. While this setup offers advantages like lower cost, easier maintenance, and better low-speed performance, it struggles with power output, especially at high RPMs, where air intake efficiency and performance are weaker, leading to a perceived lack of horsepower at higher speeds. DOHC engines experience less power loss due to the absence of valve lifters and rocker arms, resulting in greater horsepower. Additionally, the variable valve overlap angle enhances power output. Hydraulic valve control eliminates the need for valve clearance adjustments, ensuring consistent power output even as mileage increases. DOHC engines can easily adjust the timing of valve opening and closing, allowing the engine to deliver ample torque at low RPMs and maximum horsepower at high RPMs. This makes DOHC a common choice for high-displacement, high-speed engines. At high speeds, DOHC engines exhibit strong power reserves, slow power degradation, and high top speeds, making them highly capable. However, they tend to have weaker low-end torque, especially in smaller displacements. Despite this, DOHC engines can incorporate technologies like continuous variable valve timing, variable intake, turbocharging, and supercharging to compensate for these shortcomings. Moreover, for engines with displacements exceeding 1.8L, the issue of weak low-end torque becomes less pronounced.
