| 摘要 |
A multicylinder engine exhaust manifold system comprises a first manifold (24) having branches (22) leading from individual exhaust ports (20) of the engine to a downpipe (26), and a second manifold (34) for interconnecting the exhaust ports (20) and also having branches (32) leading to the individual exhaust ports (20) of the engine. The cross-sectional area of each branch (32) of the second manifold (34) facing the exhaust flow from the associated exhaust valve is no less than 25 % of the total port area and the branches of both manifolds (24, 34) terminate within the ports (20) in close proximity to the exhaust valves (18). In this way, a large proportion of the exhaust flow discharged from the exhaust valve of one cylinder is captured by the associated branch (32) of the second manifold (34) and distributed by the second manifold (34) to the exhaust ports (20) of adjacent cylinders where the exhaust valves (18) are closed and leave the exhaust ports (20) of the adjacent cylinders through the associated branches (22) of the first manifold (24), scouring the closed ends of the exhaust ports (20) in the process. |
