Intake system of outboard motor

An intake system of an outboard motor, which includes a vertically arranged V-type engine having a crankshaft extending perpendicularly therein and right and left cylinder banks opened in V-shape towards a rear side as viewed in a plan view, and in which intake ports of respective cylinders are opened to the inside of the V-shape arrangement, said intake system comprising:

• an intake manifold connected to the intake ports;
• a surge tank connected to the intake manifold and disposed at a rear side from a central portion of the engine;
• a throttle body mounted to the surge tank and provided with a throttle valve;
• a plurality of intake passages for high revolution operation of the engine, said intake passages for high revolution operation extending from the surge tank and being communicated with the intake manifold, said plural intake passages for high revolution operation having a number corresponding to a number of the cylinders of the engine;
• a plurality of intake passages for low/intermediate revolution operation of the engine, said intake passages for low/intermediate revolution operation extending from the surge tank and being joined with said intake passages for high revolution operation, respectively, said plural intake passages for low/intermediate revolution operation having a number corresponding to a number of the cylinders of the engine and each of said intake passages for low/intermediate revolution operation having a length longer than that for high revolution operation;
• and
• a valve open/close mechanism disposed for opening/closing, all at once, portions upstream side of the joined portions of the intake passages for low/intermediate revolution operation and the intake passages for high revolution operation,
• said intake passages for low/intermediate revolution operation extending, as viewed in a plan view, from both side surfaces of the surge tank towards both outsides in a width direction of an outboard motor body so as to be positioned at a rear portion of both the cylinder banks of the V-type engine, so that the surge tank and the intake passages for low/intermediate revolution operation provides a protrusion protruding towards a rear side of the V-type engine.