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This paper presents a study of the performance of a 6-cylinder, spark-ignited, port-fuel-injected, production engine modified for hydrogen fueling. The engine modifications include turbo-charging, multiple fuel injectors per port and charge-dilution control techniques. Pumping losses are reduced through ultra-lean burn and throttle-less operation alongside high charge dilution ratio control achieved by twin independent variable cam timing without external EGR. Lean-burn combustion, engine-out emissions and brake thermal efficiency results are examined in detail. In particular, low NO emissions and brake thermal efficiencies near 38% are observed experimentally at the same operating conditions. The former is explained in terms of the usual thermal NOx pathway. Usage of throttle position, injection timings and cam timings for avoiding preignition and knock over the entire engine map are also discussed.

The minimisation of tail-pipe emissions and fuel consumption during cold-start can be viewed as a constrained optimisation problem involving many parameters. Examining this problem mathematically first requires an accurate and computationally practical model of the engine and exhaust system. This paper proposes such a model for use during the cold-start of a conventional spark ignition engine. This model uses as much physics-based modelling as is computationally practical for optimisation and control studies. It takes a given set of engine control inputs to simulate tailpipe CO , HC and NO emissions, and is both calibrated and validated using detailed measurements obtained on a transient engine dynamometer following the New European Drive Cycle (NEDC).