Achates Details Light-Duty Opposed-Piston Diesel Concept

Achates Power Inc. has reported details about a new light-duty two-stroke diesel it is developing as part of its portfolio of opposed-piston engines, Green Car Congress reports.

The San Diego-based company described its latest design earlier this week at an SAE International engine symposium in Detroit.

Dubbed the OP4, the 1.5-liter two-cylinder/four-piston concept makes 129 hp and 240 lb-ft of torque. It was designed to meet Euro 6 and LEV 3 emission standards and deliver the broader speed range and low-noise operation deemed necessary for automotive applications.

Achates says the new design is 13% more fuel efficient than Daimler AG's 1.8-liter OM651 four-cylinder diesel, an engine it benchmarked for the OP4 program.

The OP4 borrows from work Achates is doing with AVL Powertrain Engineering on a three-cylinder opposed-piston diesel for the U.S. Army Tank Automotive Research, Development and Engineering Center in Warren, Mich.

The OP4 layout consists of two 0.75-liter cylinders, each containing a pair of opposed pistons and two centrally positioned fuel injectors. Each cylinder has a bore of about 76 mm (3 inches) and stroke of 167 mm (6.6 inches). The supercharged and turbocharged engine has a compression ratio is 16.0:1.

The OP4 shows 52% thermal efficiency at 1,500 rpm and 25% load, Achates reports. The company calculates that its design could meet Euro 6 standards when equipped with an oxidation catalyst and particulate filter. It says the engine could achieve LEV 3 emission limits with both those devices and an oxides of nitrogen aftertreatment system.

The company says it is looking for partners to help develop and commercialize the OP4 design.