Intake system in v-type 4-stroke engine for outboard engine system

Abstract

An intake system in a V-type 4-stroke engine for an outboard engine system is provided. A crankshaft of the engine is disposed vertically, and heads of left and right banks are disposed to face rearwards. The engine is covered with an engine hood. In the intake system, an intake air inlet is provided in an upper portion of a longitudinally flat intake air dispensing box disposed between the left and right banks and a rear wall of the engine hood, and leads to an intake passageway in a throttle body. The inside of the intake air dispensing box is divided by a partition wall into first and second dispensing chambers communicating with the intake air inlet and extending longitudinally. An on-off valve is mounted on the partition wall and is capable of bringing the first and second dispensing chambers into and out of communication with each other. Intake ports are provided in the left and right banks to communicate with the first and second dispensing chambers, respectively. Thus, it is possible to provide an intake system for a V-type 4-stroke engine in an outboard engine system, in which the air-charging characteristic can be changed in accordance with the operation state of the engine, while avoiding an increase in size of the engine hood.