A method includes operating a spark ignition engine and flowing low pressure exhaust gas recirculation (EGR) from an exhaust to an inlet of the spark ignition engine. The method includes interpreting a parameter affecting an operation of the spark ignition engine, and determining a knock index value in response to the parameter. The method further includes reducing a likelihood of engine knock in response to the knock index value exceeding a knock threshold value.

A method includes operating a spark ignition engine and flowing low pressure exhaust gas recirculation (EGR) from an exhaust to an inlet of the spark ignition engine. The method includes interpreting a parameter affecting an operation of the spark ignition engine, and determining a knock index value in response to the parameter. The method further includes reducing a likelihood of engine knock in response to the knock index value exceeding a knock threshold value.

An engine system includes a plurality of cylinders including one or more donating cylinders and one or more non-donating cylinders. A control module controls an operation of the one or more donating cylinders relative to, or based on, the operation of the one or more non-donating cylinders.

Methods and systems are provided for controlling the temperature and ratio of gases within a gas mixing tank reservoir and selectively charging/discharging gases from the reservoir to one or both of an intake system or an exhaust system. In one example, a method (or system) may include storing exhaust gas and/or compressed intake air into a gas mixing reservoir, and increasing or decreasing flow of coolant to the reservoir based on engine operating conditions. The stored gases may be discharged to an intake system and/or an exhaust system based on requests from a controller, and coolant flow to the reservoir may be adjusted based on the composition of the gases stored within the reservoir.

Various systems and methods are provided for exhaust gas recirculation. In one example, an exhaust gas recirculation (EGR) system includes an EGR passage coupling an engine exhaust system to an engine intake system, an EGR cooler positioned in the EGR passage, a recirculation passage coupling an outlet of the EGR cooler to an inlet of the EGR cooler, an EGR cooler recirculation valve positioned in the recirculation passage and controllable to change a flow of exhaust gas though the recirculation passage, and a controller configured to adjust a position of the EGR cooler recirculation valve based on a temperature at the inlet of the EGR cooler.

Various systems and methods are provided for exhaust gas recirculation. In one example, an exhaust gas recirculation (EGR) system includes an EGR passage coupling an engine exhaust system to an engine intake system, an EGR cooler positioned in the EGR passage, a recirculation passage coupling an outlet of the EGR cooler to an inlet of the EGR cooler, an EGR cooler recirculation valve positioned in the recirculation passage and controllable to change a flow of exhaust gas though the recirculation passage, and a controller configured to adjust a position of the EGR cooler recirculation valve based on a temperature at the inlet of the EGR cooler.

A combination structure of an Exhaust Gas Recirculation (EGR) cooler may include a housing open at both sides thereof, a plurality of headers inserted in both of the sides of the housing and having a circumference forming a layer with the housing, and a plurality of diffusers each including a coupling portion, which is inserted in the headers to form a layer with the housing and the headers, at a first side and having a hole for receiving and discharging exhaust gas at a second side, in which sides of the housing and the headers may be welded, and the housing, the circumference of the headers, and coupling portions of the diffusers may be welded.

A charge air cooler (CAC) device includes a body including an inlet end, an outlet end, and a plurality of passages extending between the inlet end and the outlet end. At least one of the plurality of passages is covered by an inlet blocking member at the inlet end.

A charge air cooler (CAC) device includes a body including an inlet end, an outlet end, and a plurality of passages extending between the inlet end and the outlet end. At least one of the plurality of passages is covered by an inlet blocking member at the inlet end.

A power system including an intake gas cooler and aftercooler positioned gaseously downstream thereof. The intake gas cooler is configured to receive a fresh intake gas for combusting in an engine and a recirculated exhaust gas expelled by the engine for re-combusting therein.