四气门柴油机进气道可以选用不同类型的进气道进行组合，如二个螺旋进气道、二个切向进气道或一个切向进气道一个螺旋进气道等。

There are some different ways of arranging porting for the four-valve diesel engine, such as two helical intake ports, two tangential intake ports or one helical port and one tangential port etc.

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螺旋线(气道)位于切向气道的上游，以使来自螺旋线外流的恶化减至最小，并获得切向气道气流的最佳支持。

Helical line (port) is in upstream of tangential port, minimizes the deterioration came from outflow of helical line, and obtains the best support of tangential port airflow.

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