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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.

Off-road BS III CEV (US-TIER III equivalent) emission regulations for diesel engines (i.e. Construction Equipment Vehicles) in India demands a technology upgrade to achieve a large reduction in NOx (>50%) and Particulate Matter (>50%) compared to BS II CEV emission levels. EGR is a widely accepted technology for NOx reduction in off-road engines due to lower initial and operating costs. But EGR has its own inherent deficiency of poor thermal efficiency due to lack of oxygen and further increase in soot adding complexity of meeting PM Emissions. Hence an engine meeting BS III CEV norms without EGR/SCR technologies with low initial investment is most desired solution for Indian off-road segment. This work deals with the development of an off-road diesel engine rating from 56 to 74 kW, focused mainly on in-cylinder optimization with the aid of optimum injection and charging strategies.