So gas flow around this obstruction is critical; the shape of the port an valve and the way in which the valve is lifted can all have serious effects on the engine’s final performance.

SAE Transactions, Vol. 110, Section 3: JOURNAL OF ENGINES (2001), pp. 721-730 (10 pages) We visualized behavior of crevice flows in a spark ignition gas engine by laser-induced fluorescence (LIF) of ...

Wolf Bauer, John B. Heywood, Oshin Avanessian, Derlon Chu, Flow Characteristics in Intake Port of Spark Ignition Engine Investigated by CFD and Transient Gas Temperature Measurement, SAE Transactions, ...