Achates Power and Aramco Services have developed a new, super-efficient gasoline internal-combustion engine that will start testing in the Ford F-150 later this year. The 2.7-liter mill features an opposed-piston design, with six pistons and three cylinders; uses a two-stroke cycle; and features zero spark plugs, relying instead on compression ignition.
Achates and Aramco are far from the only companies taking a novel approach to trying to squeeze every last bit of efficiency out of the internal-combustion engine. Nissan’s Infiniti brand is close to launching a turbocharged variable-compression engine that can dynamically alter its compression ratio during operation, and Mazda’s forthcoming Skyactiv-X gasoline engine is chasing greater efficiency by using a supercharger and its own clever method of compression-ignition.
Like both of those, the Achates Power/Aramco Services opposed-piston engine utilizes forced induction, in the form of both a turbocharger and a supercharger. Here, they’ll help control engine response in place of varying valve lift and timing, as there are no intake or exhaust valves.
The opposed-piston engine itself is nothing new; various examples started appearing toward the end of the 19th century, and notably, James Atkinson used an opposed-piston design for his first Atkinson Cycle engine. Over the years, opposed-piston engines have been used tanks, trucks, locomotives, and airplanes.
When the twin-charged, two-stroke opposed-piston engine of Achates Power and Aramco Services tests in the Ford F-150 later this year, the companies are hoping to see around 33 mpg – or about 37 mpg by CAFE standards. That’s because, where the typical modern internal-combustion engine can achieve somewhere around 25% thermal efficiency, Achates/Aramco say that their design can achieve about 45%.
For context, the refreshed, 2018 Ford F-150 4×2 is rated at 22 mpg combined when fitted with the 2.7L EcoBoost V6.
Testing with the Achates/Aramco-powered Ford F-150 should begin in late-2018, at which point we’ll find out whether the two companies’ efficiency forecasts are correct. If they are, the opposed-piston engine could prove an efficient, viable alternative to some of the more common engine designs.