Volumetric efficiency is a very important parameter to test whether the engine has a good process of air exchange, its also an important guide line to scale the engine performance.
充量系数是表征换气过程进行完善程度的一个极为重要的参数，是衡量发动机性能的重要指标。
2
High performance concrete should have not only high strength, but also excellent durability, relatively high crack resistance and relatively high volumetric stability, etc.