Various methods and systems are provided for reducing cylinder-to-cylinder variation in exhaust gas recirculation. In one embodiment, a system comprises a first cylinder group of an engine having a first number of cylinders, a second cylinder group of the engine having a second number of cylinders that is not an integer multiple of the first number of cylinders, and an exhaust system coupled to the first cylinder group and the second cylinder group. In at least one mode of operation, the exhaust system has exhaust ports of the first cylinder group fluidly coupled to an intake of the engine and exhaust ports of the second cylinder group fluidly decoupled from the intake.

Embodiments of outboard motors and related systems and components thereof, as well as arrangements of marine vessels implementing same, as well as related methods of operation, use, assembly, and manufacture, and related improvements, are disclosed herein. In at least some embodiments, the outboard motor includes a cowling system in which at least one divider portion separates an interior region into first and second portion, with the transmission and engine respectively being situated in the first and second portions, respectively. Additionally, in at least some embodiments, the outboard motor includes a water pump system in which a water pump is integrated with the transmission. Further, in at least some embodiments, the outboard motor includes a fuel vaporization suppression feature, or an oil tank feature that allows for desirable oil drainage from the engine of the outboard motor particularly when the outboard motor is in particular (e.g., storage) positions.

To improve fuel efficiency, some gasoline engines are equipped with valve deactivators in some of the cylinders so that at low torque conditions only a subset of the total number of cylinders are active. In prior art engines, particularly when they have four valves per cylinder, space is tight. It is known to provide a cam carrier in the head between the cylinder head and the camshaft. The cylinder head bolts pass through the head under the cam carrier. According to the present disclosure, the cam carrier, and its associated disadvantages, is obviated by widening the bearings for the camshafts, using smaller diameter head bolts, and putting the orifices tor the head bolts directly through the bearings.

An internal combustion engine has a brace and/or an engine block mounting system coupled to the engine block and arranged to reinforce and minimize deformation of the engine block. The reinforcement and reduced deformation of the engine block allows a lubrication system to provide reduced oil pressure to minimized clearances between mating internal engine components in relative motion. Meanwhile, permanent magnets are disposed in the piston, the connecting rods, and/or the crankshaft. Electromagnets are disposed in the engine block, the cylinder head, the brace, and/or the oil pan. A control system selectively provides an electrical current to the electromagnets to produce a desired magnetic field and affect the motion of the crankshaft. In at least one embodiment, the brace has a circular structure that surrounds part of the crankshaft and supports the plurality of electromagnets. In other embodiments, the brace is coupled to the main caps that support the crankshaft.

To improve fuel efficiency, some gasoline engines are equipped with valve deactivators in some of the cylinders so that at low torque conditions only a subset of the total number of cylinders are active. In prior art engines, particularly when they have four valves per cylinder, space is tight. It is known to provide a cam carrier in the head between the cylinder head and the camshaft. The cylinder head bolts pass through the head under the cam carrier. According to the present disclosure, the cam carrier, and its associated disadvantages, is obviated by widening the bearings for the camshafts, using smaller diameter head bolts, and putting the orifices for the head bolts directly through the bearings.

A method for maximizing a fuel efficiency of an engine includes the steps of providing an engine including a plurality of cylinder bores formed therein, disposing at least one first permanent magnet on a piston and at least one second permanent magnet on the throw, disposing a plurality of electromagnets in the engine block, selectively attracting and repelling the at least one first and second permanent magnets with a magnetic field of the electromagnets to affect a motion of the piston in respect of the engine block and deactivating and reactivating the plurality of cylinder bores in a desired sequence by stopping a flow of fuel thereto and a flow of electrical energy to a spark plug for a deactivated cylinder bore without deactivating an intake valve or an exhaust valve for the deactivated cylinder bore.

A cylinder head comprising a single intake valve and at least two exhaust valves per cylinder. The two or more exhaust valves may provide additional curtain area and total cross sectional area for the exhaust flow and better performance for engines equipped with a cylinder head in accordance with the present disclosure.

An engine system may include an engine including first and second cylinder banks; a throttle valve; a first exhaust manifold gathering exhaust gas exhausted from the first cylinder bank to be supplied to the first exhaust line; a second exhaust manifold gathering exhaust gas exhausted from the second cylinder bank to be supplied to the second exhaust line; a turbocharger including a turbine rotated by the exhaust gas exhausted through the first exhaust manifold and a compressor rotated in connection with the turbine; a cylinder deactivation (CDA) device selectively deactivating the cylinders of the first cylinder bank; and a supercharger including a motor and an electric compressor operated by the motor.

An air boost system for a two-cycle engine, such as an EMD engine, which operates with one or more roots blowers, or for similar engines that use gear-driven roots blowers or centrifugal blowers. At least one of the roots blowers is equipped with a variable transmission, which allows airflow into the engine to be varied in accordance with load or other engine operating conditions.

An eight cylinder engine includes cylinders that are fired at intervals corresponding to a crank angle of 90 degrees. The firing is conducted in four cylinders of each of first and second banks at uneven intervals. In a pair of cylinders of each of the banks in which the firing is consecutively conducted at an interval corresponding to a crank angle of 90 degrees, a central angle of an exhaust cam provided for one cylinder in which the firing is conducted later is larger than that of an exhaust cam provided for the other cylinder. In a pair of cylinders of each of the banks in which the firing is consecutively conducted at an interval corresponding to a crank angle of 270 degrees, a central angle of an exhaust cam provided for one cylinder in which the firing is conducted later is larger than that of an exhaust cam provided for the other cylinder.