Efficient, reliable and adaptable high-torque diesel engines are environmental polluters due to high soot emissions. Inefficient combustion due to inadequacy of injected fuel into the chamber is the major contributor of high soot emission. This work models the internal and the external dynamics of fuel spray inside the combustion chamber. The two-Fluid nozzle flow model is developed to investigate internal dynamics and cavitation inception. A realizable k- ε turbulence model is developed to capture the initiation of the external fuel flow and air turbulence negotiation inside the chamber. KH-RT fuel droplet breakup model is developed for the stated conditions. The trajectory of the evaporating droplet is predicted by the integration on the forces balance on the droplet in the Lagrangian frame of reference. The obtained results show that different sets of injection and backpressures modify the velocity and the pressure profiles, discharge and area coefficients and critical cavitation conditions. The effects of injection pressure and ambient conditions on spray characteristics are assessed in external spray phase. These results facilitate the development of better understanding of fuel spray dynamics for improved combustion process and subsequent reduction in soot formation for high-torque diesel engine.