Abstract: “This study is based on a head-cylinder provided by a French car manufacturer, which comes from a 4-cylinder 4-stroke spark-ignition engine. This head-cylinder adopts a Double-Over-Head-Camshaft (DOHC) with 16 valves, also two per cylinder. The purpose of this paper is to propose a characterization method of the air behaviour inside both the intake conduct of a head-cylinder and the cylinder. The cylinder stroke is known (from the cylinder capacity of the engine) as well as the valve dimensions (by measurements) but none internal dimensions of the conduct. The proposal method follows three main steps: firstly, internal features are extracted separately by moulding with a silicon-calcium mixture, to realize the geometrical limits of the air. This step concerns only the conduct and the combustion chamber of the head-cylinder. Secondly, the two features and one of the two valves are digitized with a Faro® laser arm to compose cloud points of their shapes. Surfaces can be then reconstituted”

Keywords: Head cylinder, spark-ignition, shapes extraction, numerical, 3D, turbulence, RSM, к-ε.