尽管发动机设计师们以迎合排气净化规范为先决条件,但是他们仍在追求发动机的高功率。一方面,按常规扩大了现有发动机的排量;另一方面,采用顶置凸轮结构以提高转速,增加比功率。在过去的十八个月中,扩大发动机排量已形成一股热潮。举最近的一些例子,如伏克斯 Engineers are still pursuing the high power of engines, although they are preconditioned to meet the exhaust gas purification regulations. On the one hand, conventionally, the displacement of existing engines has been expanded; on the other hand, overhead cam structures have been used to increase the rotational speed and increase the specific power. In the past eighteen months, the expansion of engine displacement has formed a boom. Some recent examples, such as Vokes