Worldwide, research is going on numerous types of engines that practice green and alternative energy such as natural gas engines, hydrogen engines, and electric engines. One of the possible alternatives is the air powered car. Air is abundantly available and can be effortlessly compressed to higher pressure at a very low cost. After the successful development of Compressed Air Engines, engineers shifted their focus in making this technology cost effective and feasible. This led to advancement in the field of pneumatics that is advanced Compressed Air Engine Kit (used for conversion of a small-two stroke SI engine to Compressed Air Engine) where its frugality and compatibility is kept at high priority. This research is in continuation with our previous project of development of an advanced Compressed Air Engine kit and optimisation of injection angle and injector nozzle area for maximum performance. Compressed Air Engine Kit demonstrated significant imperative results in performance testing which fuelled the need for optimizing various parameters such as injection angle, injection pressure and injector nozzle area. Most of the optimization was piloted on Injection parameters which provided substantial merits such as low cost and easy modifications with same amount of input energy required hence increasing efficiency. This paper explains another injection parameter optimization, which is Expansion ratio (Final volume / Initial volume). A number important and performance analysis were performed in order to pinpoint maximum torque and power generated which eventually leads to optimized Expansion ratio. Valuable data from previous studies and testing on above mentioned intake and injection parameters are considered in account, and testing and performance analysis is conducted after rectifying changes on injection angle and injector area. This study leads to optimization injection parameters simultaneously, which aids in eliminating power and energy losses building it more productive and efficient.