What is the difference between four-valve and two-valve engines?

[IkerMarie]

The differences between four-valve and two-valve engines are as follows: 1. Four-valve engines have larger intake and exhaust cross-sectional areas: Compared to two-valve engines, four-valve engines can increase the intake area by approximately 30% and the exhaust area by about 50%. 2. Additionally, four-valve engines have improved charging efficiency: The two intake valves create more suitable air movement, thereby enhancing mixture formation and reducing CO and HC emissions. Due to the shortened combustion duration, the formation of NOx is reduced. Lighter valve mass allows for higher engine speeds. The adoption of multiple valves increases charging efficiency and combustion speed, resulting in engine power output increasing by up to 45% and improved power per liter.