A model has been developed to predict the performance of the Texaco Controlled Combustion, Stratified Charge Engine starting from engine geometry, fuel characteristics and the operating conditions. This performance model divides the engine cycle into the following phases: Intake, Compression, Rapid Combustion, Mixing-Dominated Expansion, Heat-Transfer Dominated Expansion and Exhaust. During the rapid combustion phase, the rate of heat release is assumed to be controlled by the rate of fuel injection and the air-to-fuel ratio. The burning rate in the mixing controlled stage appears to be dominated by the rate of entrainment of the surrounding gas by the plume of burning products and this rate is assumed to be controlled by the turbulent eddy entrainment velocity.A plume geometry model has been developed to obtain the surface area of the plume for entrainment during the mixing dominated phase. The model also gives the wall areas in contact with the hot, burned gas plume and the relatively cold unburned gas for heat transfer calculations.Comparison of the model predictions with the available experimental data shows good agreement. In addition, the potential of the performance model as a design tool is demonstrated with a parametric analysis.