The other two processes, compression and process for reactive power, it must be isolated from the outside world into the cylinder combustion chamber and exhaust channel, gas leaked from the engine to ensure normal work. Responsible for the mechanical work of the agency is in the allocation of gas valve. It can be compared to the respiratory system, the inhalation of breath and lack of it can not. Along with technological development, the car's engine speed has been getting higher and higher, the modern car engine speed usually ranging from 55 to more than a minute, and completed only four of 0.005 second time, the traditional two-valve has not competent in such within a very short time to complete ventilation, restrict the engine performance. Solve this problem is the only way to expand access to the gas space. In other words is to use space for time.

Multi-valve technology is the best way to solve the problem, until the 1980s to promote multi-valve engine technology only to have the overall quality of a qualitative leap. Multi-valve engine is a cylinder valve number more than two, two into an exhaust valve and valve-three doors, two exhaust intake valve and two-door four-valve, three and two intake valve of the exhaust valve of the five-door.