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This paper is about downsizing for off road vehicle diesel engines. While fuel efficiency has to be improved, future Diesel engine emission standards will further restrict vehicle emissions, particularly of nitrogen oxides. Increased in-cylinder filling is recognized as a key factor in addressing this issue, which calls for advanced design of air and exhaust gas recirculation circuits and high cooling capabilities. Two stage turbocharging applied to off road diesel engines is a promising solution for enhancing rated power, low end torque, transient performance, better low-speed torque, longer turbo life and optimized fuel efficiency. In the new engine design, two turbochargers are arranged in series to generate increased air pressure, airflow and a superior turbocharging effect. At high altitudes, 2-stage turbocharging technology guarantees the engine's operational performance by compensating for the reduced air density.

This paper involves increase in engine power by increasing bore size and stroke length along with other required engine level design modifications. Main focus is on addressing the cooling related issues by optimizing the cooling jacket design and water pump flow parameters. Engine cooling requirements need to be upgraded to address increase in thermal loads because of reduction in cooling area between cylinder block and cylinder liner due to increase in bore size keeping engine block size fixed. Methodology used is cooling jacket optimization and water pump design modifications. In internal combustion engines, cooling system involves a complex geometry of water jackets. For such complex systems, CFD simulations can be executed in a short period of time and are relatively inexpensive. CFD provides the ability to theoretically simulate any physical condition.