A dynamic model of a piston engine has been developed to study cylinder air motion during the intake stroke. Flow visualization and paddle wheels were used to study gross flow patterns. Detailed maps of velocity at several instants during the intake stroke were obtained using hot-wire instrumentation.The model and measurement technique are described briefly. Results are presented for inlet swirl generated by streamlined port and shrouded valve configurations. Gross swirl measurements made with paddle wheels are compared with those computed from the velocity profile measurements. The effects of engine speed, compression ratio, and measuring location in the cylinder are discussed.The results show that measuring devices must be selected carefully to produce reliable data. Gross swirl measurements be interpreted with caution, using guidelines presented here.