Achates opposed-piston two-stroke diesel engine, as it would be packaged for truck installationEnlarge Photo
Could a full-size pickup truck ever get a fuel-economy rating of 37 mpg?
California-based Achates Power believes it can, and its novel engine uses a design that dates back to the earliest days of internal combustion to do so.
The company announced its two-stroke, opposed-piston diesel engine for pickup trucks in 2014, and revealed a prototype of that engine at the 2017 Detroit Auto Show.
CHECK OUT: Achates Closer To Production Of Radically Efficient Two-Stroke Truck Diesel (Oct 2014)
Called the OP-3, the 2.7-liter turbodiesel engine comes not only with that 37-mpg fuel-economy estimate, but also an estimated 270 horsepower and 479 pound-feet of torque, according to HybridCars.com.
The engine is intended for use in half-ton pickup trucks like the Ford F-150, Chevrolet Silverado 1500, and Ram 1500, although Achates noted that it could also work in "SUVs and larger CUVs."
The Ram 1500 is currently available with a conventional four-stroke 3.0-liter turbodiesel V-6, although that powerplant is now embroiled in an emissions scandal following an EPA accusation that Fiat Chrysler Automobiles failed to disclose software for the engine that may affect emissions.
2016 Ram 1500 EcoDiesel HFEEnlarge Photo
Also at the Detroit show, Ford announced a 3.0-liter V-6 turbodiesel engine for its 2018 F-150, arriving in Spring 2018.
But neither engine can match the fuel economy Achates (pronounced "Ah-KAY-dees") boasts its opposed-piston engine can achieve.
Achates was founded in 2004, and has been developing its engine designs since then.
In 2014, it noted a 30-percent improvement over the most advanced four-stroke diesel engines, and began seeking an automaker to partner with for a pilot program.
The opposed-piston engine gets its name from its configuration, in which two pistons directly face each other in one cylinder, with no cylinder head.
This is eliminates many parts, which is why Achates claims its engine will cost $1,000 less than a conventional diesel.
2018 Ford F-150Enlarge Photo
The configuration was used as early as 1882 by James Atkinson, who used opposed-piston engines to develop the Atkinson Cycle now used in the gasoline engines of many modern hybrid cars.
These engines don't have much of a history in automotive applications, but beginning in the 1930s, the Fairbanks-Morse company marketed them, primarily for use in railroad locomotives and for electric-power generation.
The two-stroke cycle used by opposed-piston engines fell out of favor with passenger cars in the 1970s.
That was because of acrid exhaust that mixed combustion leftovers with engine oil. Two-stroke engines also generally produced higher levels of noise and vibration than four-stroke engines.
2017 Chevrolet SilveradoEnlarge Photo
Achates believes modern computer-aided design and combustion modeling, as well as the current high-pressure diesel fuel injection systems can address these issues and allow its engines to meet current and future emission limits with conventional diesel-exhaust aftertreatment systems.
The company reportedly has nine development programs underway with engine manufacturers, at least some of which could lead to an automotive application.
However, industry analysts suggest the Achates engine is more likely to appear first in markets outside North America.