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Development of a 2-cylinder uneven firing engine from a 4-cylinder parent engine is associated with variation in air mass flow due to the combined effects of both engine downsizing as well the large firing gap between the cylinders especially 540°. This affects the turbocharger performance & durability and engine emissions due to fluctuations in the air mass flow. This paper investigates the effects of engine geometries such as stroke, valve overlap, cam profiles, intake and exhaust manifold configuration and surge tank effect through one-dimensional thermodynamic simulations and experimental tests, thus reducing the pulsation effect by 85%. Two engine configurations - naturally aspirated engine for 15 kVA power rating and turbocharged version for 30 kVA power rating were considered for the development study.

In heavy duty diesel engines, exhaust gas recirculation is often preferred choice to contain NOx emissions, in this a part of exhaust gas is tapped from exhaust manifold or later and recirculated to air intake pipe before intake manifold. Critical to such engines is the design of air intake pipe and intake manifold combination in view of proper exhaust gas mixing with intake air. The variation in exhaust gas mass fraction at each intake port should be as minimal as possible and this variation must be contained within +/− 10% band to have a minimal cylinder to cylinder variation of pollutants. Exhaust gas homogeneity for various intake configurations was studied using three-dimensional computational fluid dynamics for a 4 cylinder, 3.8 L, Diesel fuelled, common rail, turbocharged and intercooled heavy duty engine. Flow field was studied in the computational domain from the point before exhaust gas mixing till all the four intake ports.