The objective of this project is to study engine performance in a turbocharged diesel engine by a simulation. The simulation is programmed by Fortranlanguage with respect to engine speed, torbocharger speed,combustion efficiency, fuel pump rack position, boost pressure, airflow, air-fuel ratio and exhaust temperature. Result form the present simulation is compared to others simulation in order to ensure whether the programmed gives a good engine performance. This comparison proved that the result are approximately similar.