Turbo lag and low starting torque is the challenges of turbochargers. These challenges can be met with the implementation of an additional boosting device which can significantly boost the starting torque of the engine. the goal of this study is to show how the steady-state performance of a turbocharged SI engine can be improved by supercharging turbocharged engine. A one dimensional model for a turbocharged V type, four cylinder CNG engine has been developed and studied in detail using GT-POWER software. For validation purposes the model results are compared with experimental data available where acceptable results with good accuracy has been observed.