A variable valve duration system may include a camshaft, a first cam portion including a first cam, into which the camshaft is inserted and of which a relative phase angle of the first cam with respect to the camshaft is variable, an inner bracket transmitting rotation of the camshaft to the first cam portion, a slider housing into which the inner bracket is rotatably inserted, a first rocker arm having a first end contacting the first cam and a second end connected to a first valve, a rocker shaft to which the first rocker arm is rotatably connected, a solenoid valve to selectively supply hydraulic pressure, and a position controller to selectively change a position of the slider housing according to the selective supplying of the hydraulic pressure from the solenoid valve.

Methods and systems are provided for operating an engine in a two-valve diagonal blow-through mode during which a majority of blow-through is directed via a first intake valve positioned diagonally across a first exhaust valve in order to increase a distance of flow path from the intake valve to the exhaust valve.

A valve actuation system for actuating at least one of two or more engine valves in an internal combustion engine comprises at least one motion source including a first motion source configured to provide an exhaust main valve event. A valve train for conveying valve events from the at least one motion source to the two or more engine valves comprises a lost motion component for selectively conveying valve events to the at least one of the two or more engine valves. A phasing assembly is configured to advance a phase of at least the first motion source and the exhaust main valve event. The at least one motion source is configured to provide a recompression relief valve event to the at least one of the two or more engine valves when the phase of the exhaust main valve event is advanced.

An internal-combustion engine has a plurality of cylinders each with two intake valves driven by respective pumping pistons operatively associated to cams of a camshaft, by respective hydraulic circuits. The hydraulic has its pressure chamber communicating with hydraulic actuators of the two intake valves, so that the two intake valves of each cylinder are controlled, via two different hydraulic circuits, by cams associated to two different cylinders. Each cam is configured to give rise to a cycle of opening and closing of each of the intake valves in an angular range of rotation of the crankshaft less than 180 such that, in each operating cycle of a cylinder, only the first intake valve initially opens and closes while the second intake valve remains closed, and then the second intake valve opens and closes while the first intake valve remains closed.

A valve actuation system for actuating at least one of two or more engine valves in an internal combustion engine comprises at least one motion source including a first motion source configured to provide an exhaust main valve event. A valve train for conveying valve events from the at least one motion source to the two or more engine valves comprises a lost motion component for selectively conveying valve events to the at least one of the two or more engine valves. A phasing assembly is configured to advance a phase of at least the first motion source and the exhaust main valve event. The at least one motion source is configured to provide a recompression relief valve event to the at least one of the two or more engine valves when the phase of the exhaust main valve event is advanced.

An exhaust system includes a plurality of cylinders, and each cylinder includes a scavenge exhaust valve and a blowdown exhaust valve. A scavenge path leads from the scavenge exhaust valves and a blowdown path leads from the blowdown exhaust valves. An arrangement activates and deactivates the scavenge exhaust valves and the blowdown exhaust valves. Further included is a cam shaft including a plurality of scavenge cams and a plurality of blowdown cams. During rotation of the cam shaft, the scavenge cams interact with the scavenge exhaust valves to open and close the scavenge exhaust valves when the scavenge exhaust valves are activated. Additionally, during rotation of the cam shaft, the blowdown cams interact with the blowdown exhaust valves to open and close the blowdown exhaust valves when the blowdown exhaust valves are activated, and at different times with respect to the opening and closing of the scavenge exhaust valves.