The general engine has two valves per cylinder, namely an intake valve and an exhaust valve. The diameter of the intake valve head is 15% to 30% larger than that of the exhaust valve, the purpose is to increase the area of the intake valve through the section, reduce the intake resistance, and increase the intake volume. If the number of intake valves and exhaust valves is the same, the diameter of the intake valve head is always larger than that of the exhaust valve. An engine with two valves per cylinder is also called a two-valve engine. Modern high-performance automotive engines generally use three, four, five valves per cylinder, especially four-valve engines.…