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This paper presents experimental results of a 10.6L, three-cylinder opposed-piston (OP) operating on diesel fuel designed for heavy duty (Class 8) operation. The paper will describe the engine configuration and calibration of both catalyst light-off and high efficiency modes. Analysis based on measured results show the engine can comply with all 2027 California Air Resourced Board (CARB) and Environmental Protection Agency (EPA) requirements for CO2 and criteria emissions. Due to the ability of the OP Engine to combine low oxides of nitrogen (NOX) flux with high exhaust enthalpy for early catalyst light off, the engine can meet all 2027 CARB and EPA NOX standards with a current, state of the art conventional underfloor aftertreatment system. No additional emissions control technology is required.

Opposed-piston 2-stroke (OP-2S) engines have the potential to achieve higher thermal efficiency than a typical diesel engine. However, the uniflow scavenging process is difficult to control over a wide range of speeds and loads. Scavenging performance is highly sensitive to pressure dynamics, port timings, and port design. This study proposes an analysis of the effects of port vane angle on the scavenging performance of an opposed-piston 2-stroke engine via simulation. A CFD model of a three-cylinder opposed-piston 2-stroke was developed and validated against experimental data collected by Achates Power Inc. One of the three cylinders was then isolated in a new model and simulated using cycle-averaged and cylinder-averaged initial/boundary conditions. This isolated cylinder model was used to efficiently sweep port angles from 12 degrees to 29 degrees at different pressure ratios.