Abstract: The subject matter of this specification can be embodied in, among other things, an engine system that includes an intake manifold configured to receive and convey air to a combustion chamber, an intake valve upstream of the intake manifold and configured to regulate an air flow into the intake manifold, an exhaust manifold configured to receive combustion products from the combustion chamber, a recirculation flow passage configured to convey exhaust gasses from the exhaust manifold to the intake manifold, a recirculation flow control valve configured to regulate gas flow through the recirculation flow passage, and a controller configured to determine that the engine system is in a motoring condition, open, during the motoring condition and based the determining, the recirculation flow control valve, and close, during the motoring condition and based the determining, the intake valve.

Abstract: The subject matter of this specification can be embodied in, among other things, an engine system that includes an intake manifold configured to receive and convey air to a combustion chamber, an intake valve upstream of the intake manifold and configured to regulate an air flow into the intake manifold, an exhaust manifold configured to receive combustion products from the combustion chamber, a recirculation flow passage configured to convey exhaust gasses from the exhaust manifold to the intake manifold, a recirculation flow control valve configured to regulate gas flow through the recirculation flow passage, and a controller configured to determine that the engine system is in a motoring condition, open, during the motoring condition and based the determining, the recirculation flow control valve, and close, during the motoring condition and based the determining, the intake valve.

Abstract: A convergent nozzle is in a mixer housing and in a flow path from an air inlet of the mixer to an outlet of the mixer. A convergent-divergent nozzle is in the mixer housing and includes an air-exhaust gas inlet in fluid communication to receive fluid flow from the convergent nozzle and from the interior of the exhaust gas housing. A first nozzle module is configured to be received in the mixer housing and, when received in the mixer housing, define at least a portion of the convergent nozzle or the convergent-divergent nozzle. A second nozzle module is configured to be received in the mixer housing separate from the first nozzle module. The second nozzle module, when received in the mixer housing, is configured to define at least a portion of the convergent or the convergent-divergent nozzle. The second nozzle module has a different flow characteristic than the first nozzle module.

Abstract: A convergent nozzle is in a mixer housing and in a flow path from an air inlet of the mixer to an outlet of the mixer. A convergent-divergent nozzle is in the mixer housing and includes an air-exhaust gas inlet in fluid communication to receive fluid flow from the convergent nozzle and from the interior of the exhaust gas housing. A first nozzle module is configured to be received in the mixer housing and, when received in the mixer housing, define at least a portion of the convergent nozzle or the convergent-divergent nozzle. A second nozzle module is configured to be received in the mixer housing separate from the first nozzle module. The second nozzle module, when received in the mixer housing, is configured to define at least a portion of the convergent or the convergent-divergent nozzle. The second nozzle module has a different flow characteristic than the first nozzle module.