Abstract: An exhaust device includes a plurality of independent exhaust passages connected to an exhaust port of one cylinder or a plurality of cylinders that are non-sequential in exhaust order, and a mixing pipe into which exhaust that has passed through the respective independent exhaust passages flows. The downstream ends of the respective independent exhaust passages are connected in a bundled form to the upstream end of the mixing pipe. A cavity expansion chamber is disposed in an exhaust passage downstream from the mixing pipe. The cavity expansion chamber is disposed in a position (at a distance L2) such that, in the intermediate speed range, a negative pressure wave generated due to an exhaust pressure wave generated by opening an exhaust valve being reflected by the cavity expansion chamber reaches the exhaust port during an overlap period of the exhaust valve and an intake valve of the cylinder.

Abstract: An intake and exhaust apparatus of a multi-cylinder engine is provided. The engine is provided with a plurality of cylinders having intake and exhaust valves for opening and closing intake and exhaust ports, respectively. The apparatus includes an intake system including intake ports of respective cylinders, independent intake passages connected with the respective intake ports, a surge tank connected with upstream ends of the independent intake passages, and an air cleaner connected with the surge tank. The apparatus also includes an exhaust system including independent exhaust passages connected with an exhaust port of one cylinder or exhaust ports of the plurality of cylinders that are not continuous in exhausting order, and a collecting pipe connected with downstream ends of the independent exhaust passages in a bundled manner, and for collecting exhaust gas ejected from the downstream ends of the independent exhaust passages.

Abstract: An exhaust device includes a plurality of independent exhaust passages connected to an exhaust port of one cylinder or a plurality of cylinders that are non-sequential in exhaust order, and a mixing pipe into which exhaust that has passed through the respective independent exhaust passages flows. The downstream ends of the respective independent exhaust passages are connected in a bundled form to the upstream end of the mixing pipe. A cavity expansion chamber is disposed in an exhaust passage downstream from the mixing pipe. The cavity expansion chamber is disposed in a position (at a distance L2) such that, in the intermediate speed range, a negative pressure wave generated due to an exhaust pressure wave generated by opening an exhaust valve being reflected by the cavity expansion chamber reaches the exhaust port during an overlap period of the exhaust valve and an intake valve of the cylinder.