Helical inlet port with flat wall portion

摘要

The present invention relates to a cylinder head for an internal combustion engine of the reciprocating piston type, and in particular to a helical inlet port 1 with a flat wall portion (2) in a section of the port (20) upstream of a bowl-shaped recess (6) about a valve stem guide (8). The flat walled section (2) meets a generally cylindrical portion of the recess (6) adjacent a cusp-shaped swirl edge (18). The orientation of the flat portion (2) with respect to a reference feature, such as the axis of the valve stem guide (8), may then be used as a measure of the accuracy of casting of the inlet port, and may also be altered if so desired to vary the swirl characteristics of the inlet port (1).