The 1,500 kW EMD 16-645E engine is popular in switcher and shunter locomotive applications for railroads in North America. These locomotives are typically lightly loaded with extended periods of idle operation, and usually operate in large urban areas. With the advent of EPA emissions standards, and increasing fuel costs, many in the railroad industry are looking at replacing these locomotives with hybrid locomotives, installing APU systems or automatic start stops systems, repowering with newer engines, or using new technology to reduce emissions and improve fuel consumption. This paper documents results of research into ways to improve idle and low power emissions and fuel consumption from these roots-blown two-cycle EMD 645E engines. Specifically, this research looked at disabling one bank of injectors to simulate skip fire operation, and the stopping the rotation of one of the two roots-type blowers used to supply boost air to the uni-flow, two-cycle, diesel engine. The results of this work demonstrated that the EMD 16-645E engine did not respond positively when the injectors of one cylinder bank were disabled (simulating bank to bank skip fire operation). However, the engine did demonstrate both a reduction of NOx emissions and brake specific fuel consumption, over the US-EPA switcher and line haul emissions cycles, while operating on only one of the two blowers at idle and light loads. Additionally this concept of blower cut-out allows for reduced mass flow and higher exhaust temperatures at light loads, which could be beneficial for future application of exhaust aftertreatment. However, there is an associated increase in particulate matter emissions.

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