The combustion characteristics, performance, and emission analysis of a single cylinder compression ignition engine are investigated in this paper using GT-Power software.  For result analysis four cases of engine rotation are considered here in this study such as 2400,3000,3600,4000 RPM. Inlet and outlet conditions are assumed to be same for modelling. The input values of pressure and temperature at inlet conditions have been assumed as output values from the turbocharger because this engine model is designed as a turbocharger-less model. Fuel mass injection, start of injection, start of combustion, injection timing, combustion duration, and mass fraction burned in premixed and diffusion combustion had taken as a fixed value. Different sub-models such as inlet environment, intake runner, intake port, inlet valve, fuel injection, cylinder, crank train, outlet environment, exhaust valve, port and runner are connected together for analysis. Some parameters are taken from GT-suite template library. After modelling simulation run for 10 cylces and the results obtained are, If the rpm goes on increasing the cylinder pressure, cumulative heat release rate, engine torque, Brake power, brake mean effective pressure, concentration of NOx in ppm increases and hydrogen concentration and CO concentration in ppm decreases.