Abstract: A marine drive is configured to propel a marine vessel in a body of water. The marine drive has an engine; a primary exhaust conduit receiving exhaust gases from the engine and discharging the exhaust gases to a primary exhaust outlet discharging the exhaust gases to the body of water; an idle relief exhaust outlet discharging exhaust gases to atmosphere, above the body of water; a primary idle relief muffler receiving exhaust gases from the primary exhaust conduit; a secondary idle relief muffler receiving exhaust gases from the primary idle relief muffler; and a tertiary idle relief muffler configured to receive exhaust gases from the secondary idle relief muffler and discharges exhaust gases to atmosphere via the idle relief exhaust outlet.

Abstract: An intake manifold is for a marine engine having a throttle for controlling flow of intake air to the marine engine. The intake manifold has a plenum for receiving the intake air from the throttle, a plurality of intake runners which extends from upstream ends for receiving the intake air from the plenum to downstream ends for discharging the intake air to the marine engine, and a quarter wave resonator extending from an open end coupled to the plenum to a closed end, the quarter wave resonator having a tuned elongated cavity configured to attenuate sound emanating from the marine engine via the plurality of intake runners.

Abstract: An exhaust manifold is disclosed that enhances the purification efficiency and lifetime of the catalyst in a catalytic converter. The manifold includes: a mixing chamber of a spheroidal shape having runners, each runner having one end connected to an exhaust port and the other end to the mixing chamber along the outer circumference thereof at an angle that causes rotation of the entering exhaust; and a diffuser to induce exhaust gas to diffuse widely before passing through the catalytic converter.

Abstract: The present invention relates to a device for varying the fuel-air mixture flow to an engine, and more particularly, to a device for varying the fuel-air mixture flow to the engine that can change the fuel-air mixture reaching the combustion chamber, thus improving fuel combustion and reducing pollution. A preferred embodiment of the invention delays spark timing based on engine speed and fuel-air mixture flow to further improve engine performance. The device comprises an actuator and a manipulator for changing the fuel-air mixture flow through an intake manifold into the engine in response to control signals transmitted from an electronic control unit.

Abstract: The present invention relates to a device for varying the fuel-air mixture flow to an engine, and more particularly, to a device for varying the fuel-air mixture flow to the engine that can change the fuel-air mixture reaching the combustion chamber, thus improving fuel combustion and reducing pollution. A preferred embodiment of the invention delays spark timing based on engine speed and fuel-air mixture flow to further improve engine performance. The device comprises an actuator and a manipulator for changing the fuel-air mixture flow through an intake manifold into the engine in response to control signals transmitted from an electronic control unit.

Abstract: An exhaust manifold is disclosed that enhances the purification efficiency and lifetime of the catalyst in a catalytic converter. The manifold includes: a mixing chamber of a spheroidal shape having runners, each runner having one end connected to an exhaust port and the other end to the mixing chamber along the outer circumference thereof at an angle that causes rotation of the entering exhaust; and a diffuser to induce exhaust gas to diffuse widely before passing through the catalytic converter.