Patent ID: 8875503

Claim:
An internal combustion engine exhaust system comprising: an exhaust gas-cooling pipe element provided between an exhaust port and an exhaust branch pipe, the exhaust gas-cooling element having a plurality of exhaust channels, each of the plurality of exhaust channels has an exhaust introduction opening and an exhaust discharge opening; wherein an opening portion of the exhaust port and an opening portion of the exhaust branch pipe that are connected by each of the exhaust gas-cooling channels of the exhaust gas-cooling pipe element are disposed so that the opening portion of the exhaust port is positioned above the opening portion of the exhaust branch pipe in a vertical direction, and wherein a central axis of the opening of the exhaust port and a center axis of the opening of the exhaust branch pipe are non-parallel to each other, wherein the exhaust gas-cooling pipe element includes a pipe wall in which a cooling fluid passageway and a communication hole are formed, the communication hole provides communication between the cooling fluid passageway and an outside, the communication hole is closed with a plug, the communication hole is provided above the cooling fluid passageway in the vertical direction, and an axis direction of the communication hole is angled to the vertical direction.