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Reported in the current paper is a study into the cycle efficiency effects of utilising a complex valvetrain mechanism in order to generate variable in-cylinder charge motion and therefore alter the dilution tolerance of a Direct Injection Spark Ignition (DISI) engine. A Jaguar Land Rover Single Cylinder Research Engine (SCRE) was operated at a number of engine speeds and loads with the dilution fraction varied accordingly (excess air (lean), external Exhaust Gas Residuals (EGR) or some combination of both). For each engine speed, load and dilution fraction, the engine was operated with either both intake valves fully open - Dual Valve Actuation (DVA) - or one valve completely closed - Single Valve Actuation (SVA) mode. The engine was operated in DVA and SVA modes with EGR fractions up to 20% with the excess air dilution (Lambda) increased (to approximately 1.8) until combustion stability was duly compromised.

Vehicle manufacturers will need to overhaul current development methods used to guarantee emissions compliance with the introduction of more stringent emissions legislation. Climatic boundaries of temperature and altitude and in-service conformity mileage compliance will likely be extended alongside alterations to trip dynamics; this will require robust calibrations for emissions compliance. Consequently, assessing this vast array of scenarios will be impossible with physical testing of prototype vehicles and overseas climatic testing alone. To reduce reliance on physical testing for compliance, a frontloading vehicle and powertrain development programme has been established where road, chassis dynamometer, Engine-in-the-Loop (EiL) and digital twin virtual toolset methodologies are used.