What is the relationship between the number of engine intake and exhaust valves and performance?

What is the relationship between the number of engine intake and exhaust valves and performance?

"The intake and exhaust valves of an internal combustion engine are valves located at the top, intake and exhaust ports. As the name suggests, the intake port is responsible for opening the oil gas mixing passage and allowing it to enter the cylinder for combustion. The exhaust valve is composed of the intake and exhaust ports, while the exhaust valve is composed of the intake and exhaust ports.". The valve core is pressed open by the camshaft, and the valve spring is responsible for closing. If it is necessary to absorb the mixture into the cylinder, the air inlet will be opened; When it is necessary to exhaust the exhaust gas after combustion, the exhaust port will open.

Because intake air is sucked in and exhaust air is pushed out, intake air is more difficult than exhaust air; Actually, this is easy to understand. "You just think about smoking. Do you have to work harder when smoking? It's easy to smoke.". For an engine, the more intake air, the better combustion, and the better engine performance. Therefore, the intake valve is generally designed to be larger than the exhaust valve to reduce intake difficulty and increase intake volume. There are several simple design intake valves, which only have 3 valves (2 in 1 row) and 5 valves (3 in 1 row).

In fact, the more valves, the better. Indeed, multi valve engines have the advantages of high speed and efficiency. The higher the threshold value, the higher the timing speed, the better the exhaust effect, and the definitely higher the engine performance. However, everything has two sides, and multifaceted nature is a double-edged sword. Although the engine performance produced by the intake and exhaust valve manufacturers has improved, the multi valve design is also relatively complex, and the valve drive mode is also relatively complex. The combustion chamber structure and spark plug locations should be accurately arranged, and engineers do not know how many brain cells will die. At the same time, multiple valves also raise manufacturing costs, as multiple valves require a higher level of craftsmanship. As soon as the cost increases, the blood pressure of car owners increases. For car owners, the late maintenance costs of multi valve engines are also relatively high. So generally speaking, although multi valve engines have advantages in performance, considering so many disadvantages is still a bit uneconomical. Therefore, most automobile manufacturers have basically abandoned multi valve engines (such as 5 valves), and now 4 valves per cylinder is the mainstream.