Abstract: Operating a gaseous fuel engine includes spark-igniting gaseous hydrogen fuel and air, and propagating combustion gases of the spark-ignited mixture outwardly from a spark gap. The propagating combustion gases are impinged upon a cone surface of a piston so as to limit a flame area of the propagating combustion gases. Additional gaseous hydrogen fuel and air is ignited in the combustion cylinder by way of the propagating combustion gases to urge a piston toward a bottom-dead-center position.

Abstract: Operating a gaseous fuel engine system includes conveying hydrogen fuel and hydrocarbon fuel into a cylinder in a gaseous fuel engine for combustion. Operating a gaseous fuel engine system further includes receiving an increased engine power output request, boosting a power output of the gaseous fuel engine by varying a ratio of the hydrogen fuel and the hydrocarbon fuel combusted in the cylinder, and varying an in-cylinder combustion parameter based on the varying a ratio. Perturbation to a performance profile of the gaseous fuel engine is thereby limited. Related apparatus and control logic is also disclosed.

Abstract: An engine system includes a cylinder block, and a cylinder head attached to the cylinder block and including exhaust ports. Exhaust collection passages are formed in the cylinder head and each fluidly connect to one of the exhaust ports. An unburned hydrocarbon (UHC) emissions mitigation conduit fluidly connects to the exhaust ports to route UHC to an oxidation catalyst or for recirculation.

Abstract: Operating a gaseous fuel engine system includes spark-igniting a gaseous hydrogen fuel and air in a prechamber sparkplug to ignite a main charge containing gaseous hydrogen fuel and air in a cylinder. Operating the gaseous fuel engine system also includes determining a preignition condition and conveying cooling air to the prechamber sparkplug based on the preignition condition to limit preignition of gaseous hydrogen fuel and air in the prechamber sparkplug. Related apparatus and control logic is also disclosed.

Abstract: Operating a gaseous fuel engine includes spark-igniting gaseous hydrogen fuel and air, and propagating combustion gases of the spark-ignited mixture outwardly from a spark gap. The propagating combustion gases are impinged upon a cone surface of a piston so as to limit a flame area of the propagating combustion gases. Additional gaseous hydrogen fuel and air is ignited in the combustion cylinder by way of the propagating combustion gases to urge a piston toward a bottom-dead-center position.