The Achates Power opposed-piston engine, is modeled after the opposed-piston architecture made popular by the Junkers Jumo 205/207 aviation engines developed in the 1930s. The design positions two pistons per cylinder—working in opposite, reciprocating motion. Achates Power is an American developer of opposed-piston, two-stroke, compression ignition engines for use in commercial and passenger vehicles.
source-image: Engineering Explained
This eliminates parts including the cylinder head and valvetrain, improving overall engine efficiency as these components are considered primary contributors to heat and friction losses.The Achates Power opposed-piston engine is packed full of unique technology. The supercharged, turbocharged, diesel 3 cylinder makes use of six pistons, two of which operate in each cylinder.
source-image: Engineering Explained
It’s a two-stroke design, meaning every time the pistons come together a power stroke occurs, forcing both pistons away from one another and rotating their respective crankshafts. The two crankshafts are geared together to a common output shaft, which powers the vehicle.
source-image: Engineering Explained
Research has shown two-stroke opposed piston engines to be wildly efficient. 3 cylinder designs are the most efficient, and it’s possible to achieve brake thermal efficiencies as high as 55%, a massive improvement for road car engines. The engine in this video is a 2.7L 3-cylinder producing 270 HP and 480 lb-ft of torque.
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The cylinder head and valvetrain systems are also among the most complex and costly elements of conventional engines. The two-stroke cycle compounds the efficiency benefits of the opposed-piston engine architecture.
With this cycle, each combustion event is shorter in duration and, therefore, closer to optimum timing as compared to four-stroke engines.Achates claims that its two-stroke opposed piston engine can achieve lower emissions of nitrogen oxides (NOx) than an equivalent four-stroke engine for several reasons.
