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A comprehensive experimental and theoretical approach was undertaken to understand the phenomenon of pre-ignition and to assess parameters to improve or even eliminate it completely. Oil mixing with fuel was identified as the leading theory of self ignition of the fuel. End of compression temperature has to meet a minimum level for pre-ignition to take place. In this work a comprehensive list of parameters were identified that have a direct and crucial role in the onset of pre-ignition including liner wetting, injection targeting, stratification, mixture motion and oil formulation. Many secondary effects were identified including ring dynamics, ring tension, spark plug electrode temperature and coolant temperature. CFD has been extensively used to understand test results including wall film, A/F ratio distribution and temperature at the end of compression when looked at in the context of fuel evaporation and mixing.

The adaptation of a Dual Continuous Variable Cam Phasing (DCVCP) system provides increased volumetric efficiency at wide open throttle (WOT) conditions and considerable potential to minimize fuel consumption by allowing internal exhaust gas recirculation and the associated pumping loss reduction. To exploit the full benefits of a DCVCP system significant development work has to be carried out to design the airflow path, combustion chamber, the hydraulic system and timing drive. The selected cam phasing authority of 45 crank degrees on the exhaust VCP and 60 crank degrees on the inlet VCP required attention to the actuation speed and setting accuracy. Particular focus was given to the development of the oil circuit pressure and flow requirements to cover oil temperatures from -30°C up to 140°C, and to the cam drive system for the higher inertia moments.