| 摘要 |
PURPOSE:To improve the combustivity by specifying the valve timing of cylinder groups as well as furnishing a means to make a part of the exhaust gas reflow in to a combustion chamber while swirling around the cylinder shaft, in an engine in which suction valves and exhaust valves are arranged at a cylinder head. CONSTITUTION:When a six-cylinder engine is used, two suction valves 24 and two exhaust valves 26 are arranged at a cylinder head respectively. One of two exhaust ports 22 is formed in almost a straight line to the branch pipe 50a of an exhaust maniford 50, opened in the tangent direction at the combustion chamber 18, while the other exhaust port 22 is formed making an angle. And by making the reflowing of the exhaust gas to the combustion chamber 18 through the exhaust port 22 of the almost straight line side by the effect of inertia, a swirl S can be formed in the combustion chamber 18. Furthermore, the valve timing of the two separate cylinder groups is set to avoid the opening period of the exhaust valve 26 of one cylinder from overlapping to that of the other cylinders.
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