Turbocharging a Small Two Cylinder DI Diesel Engine - Experiences in Improving the Power, Low End Torque and Specific Fuel Consumption 2011-24-0133

Turbocharged common rail direct injection engines offer multiple benefits compared to their naturally aspirated counterparts by allowing for a significant increase in the power and torque output, while simultaneously improving the specific fuel consumption and smoke. They also make it possible for the engine to operate at a leaner air/fuel mixture ratio, thereby reducing particulate matter emission and permitting higher EGR flow rates.

In the present work, a two cylinder, naturally aspirated common rail injected engine for use on a load carrier platform has been fitted with a turbocharger for improving the power and torque output, so that the engine can be used in a vehicle with a higher kerb weight. The basic architecture and hardware remain unchanged between the naturally aspirated and turbocharged versions. A fixed geometry, waste gated turbocharger with intercooling is used.

With the help of an appropriately selected waste gate turbocharger, the naturally aspirated engine delivering 20 kW/lit peak specific power and 60.5 Nm/lit maximum specific torque is upgraded to deliver about 80% higher peak power and more than 75% higher peak torque with a wider peak torque band. Specific fuel consumption and smoke also show an improvement, while the peak firing pressure and turbine inlet temperature are kept within the system limits. It is shown that specific peak power can be increased by more than 80% and torque by close to 110% over the NA configuration by reducing the compression ratio. Peak power and torque are further raised by about 140% and more than 130% respectively over the NA engine with the help of a variable geometry turbocharger and reduced compression ratio. Benefits in fuel economy, emissions and noise are also obtained.

Turbocharging, therefore, is an important step to increase power density and meet future emission norms in small single and two cylinder load and passenger carrying vehicles in developing countries, which are typically naturally aspirated, and usually incapable of achieving emission norms beyond Euro-III equivalent.