One year ago at the Detroit auto show, a company called Achates Power unveiled models of a new kind of internal-combustion engine.
With opposed pistons in the middle and crankshafts at either end, it was sufficiently different to startle most visitors who paid attention.
That engine came with some audacious claims, too: How about an EPA combined fuel-economy rating of 37 mpg when fitted in a full-size Ford F-150 pickup truck?
One year later, at this week's 2018 North American International Auto Show in Detroit, Achates ("Ah-CAY-tees") showed its 2.7-liter engine in an F-150 and announced a partnership to develop and refine the engine for on-road testing.
In line with efforts by Infiniti and Mazda to bring to market homogenous charge-compression ignition engines, the two-stroke Achates powerplant ignites a very lean gasoline-air mixture purely through compression—giving it diesel-like characteristics.
Achates was founded in 2004, and has been developing its engine designs since then.
Achates 2.7-liter opposed-piston gasoline compression-igntion engine in Ford F-150 test pickup truck
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.
The company designed and developed its engine with $9 million in funds from the U.S. Department of Energy's ARPA-E program, in conjunction with both Argonne National Laboratory and auto-parts maker Delphi.
In Detroit, Achates said it had formed a joint-development agreement with consultant Aramco Services. Financial terms were not specified.
Does the name Aramco sound familiar? It's the Houston-based U.S. subsidiary of the giant oil company Saudi Aramco, the national oil and gas company of Saudi Arabia.
Aramco Services, it says, "supports a wide range of activities from facilitating the safe and reliable delivery of energy to customers around the world to pushing for breakthroughs in research and innovation."
Achates 2.7-liter opposed-piston gasoline compression-igntion engine
Among those activities, the leader of its research center, Dave Cleary, is consulting with numerous makers on technologies to reduce the carbon emissions of a wide variety of vehicles.
Those engagements are almost exclusively for combustion engines, which Cleary notes now power almost all of the road vehicles on the planet.
Asked whether electrification was part of those research activities, Cleary cited one mild-hybrid program it had contributed to.
With Aramco's help, Achates will develop the technology toward production and defray the costs of those activities.
It ultimately intends to license its design to vehicle and engine makers throughout the world, said CEO David Johnson, but doesn't intend to manufacture engines itself.
The company reportedly has nine development programs underway with engine manufacturers, at least some of which could lead to an automotive application.
Achates opposed-piston two-stroke diesel engine, as it would be packaged for truck installation
Achates opposed-piston two-stroke diesel engine: Surface-to-Volume Ratio vs Displacement
Achates opposed-piston two-stroke diesel engine vs Cummins Atlas advanced diesel - test results
“Aramco has incredible research and development capabilities, focused on improving the emissions and efficiency of the internal combustion engine, and we’re happy to be working with them,” said Achates CEO Johnson.
The two companies will jointly continue development and testing of at least five Achates engines, and soon more, both at the company's headquarters in San Diego and Aramco Services' research center in the Detroit area.
They expect that working engines will be fully integrated into their test Ford F-150, and that the truck will be drivable before the end of this year.
The partners promised that media outlets will be invited to drive those development vehicles to get a sense of what the radical new engine design is like in real-world conditions.