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Achates Power addresses commercial truck mileage and emission standards

In a private interview with Torque News at the CAR Management Business Seminars 2011, David Johnson, President and CEO of Achates Power, discussed the role that its engine technologies using opposed pistons will contribute toward lower emissions and better fuel economy for commercial trucks.


In a timely interview one week before President Obama announces the first U.S. CO2 emission rules for heavy trucks in Springfield, VA today, Achates Power, showed why it participated in the 2011 CAR Management Business Seminars in Traverse City, Michigan. Based in San Diego, California, Achates develops radically improved internal combustion engines.

Its mission, according to CEO and President, David Johnson, is to build fundamentally better engines to respond directly to the critical environment and economic needs of the global transportation industry. When asked about brake thermal efficiency, he noted that gasoline IC engines are in the 30-33% range; diesel engines are in the 35-40% range; and the Achates engine is in the 45-50% range.

When asked whether Achates' focus was on autos or trucks, his reply was that the commercial truck industry has the greater need; and it stands to gain the most in efficiency, mileage and emission reductions.

Achates Power Engine Technology

According to Achates website, and based on J.-P. Pirault, and M. Flint, Opposed Piston Engines: Evolution, Use, and Future Applications, SAE International, 2009, throughout the 20th century, when the utmost fuel, weight and volume efficiencies were required to propel aircrafts, ships and vehicles, an unconventional type of compression ignition engine was used: opposed-piston engines.

However, the Achates engine is described as a two-stroke diesel; hence, the natural inclination toward trucks. That also makes it a compression-ignition engine, but one that that depends on uniflow scavenging.

It first seeks thermodynamic efficiency as well as part reduction. Based on an opposed-piston architecture, two pistons per cylinder literally work in opposite reciprocating action. That means these engines do not need cylinder heads which are a major contributor to heat losses in conventional engines.

Ports in the cylinder walls replace the complex poppet valves and friction-creating valve trains of conventional engines. The intake ports at one end of the cylinder and exhaust ports at the other are activated by the piston motion and enable efficient uniflow air scavenging.

In the past, these advantages were balanced by some well-documented shortcomings of two-stroke engines, which limited their scope of use. High hydrocarbon emissions was one of them due to carburetion and over-scavenging. The second was excessive oil consumption due to oil-fuel mixing in spark-ignition engines and port oil ejection in compression ignition, direct fuel injection engines.

While those were difficult issues to tackle in these type of engines, the engineers and scientists started Achates Power in 2004 with the audacious idea that innovation and modern technology could transform the proven and record-setting two-stroke opposed-piston engines of the past into the clean and efficient engines of the future.

Back to the Achates Interview

Johnson was quick to point out that compression ignition with diesel fuel is the combination of choice for the commercial transportation of goods and people on road, rail and water.

Fact is, according to UN and ACAE data, in the US alone, 25 percent of the fuel used by cars, trucks and buses is diesel fuel. In China and India, diesel represents 66 percent of the fuel used for road transportation; and 50 percent of all two-passenger cars registered in Europe is compression ignition/diesel powered.

When I questioned him on natural gas where the U.S. has plentiful supplies, he noted the Achates engine was nat-gas capable, and would benefit from the thermodynamic efficiency of the opposed-piston design. However, he also noted that nat-gas is not as energy dense.

Still, for the record, some sort of post combustion treatment is still needed for diesel. And that is what I confirmed at the 2011 NAIAS as well as the 2011 SAE World Congress in Detroit.

Johnson also made a statement that is well worth remembering. With regard to engine efficiency and emissions, he said, “The problem is not regional, but global.”

Final TN Comments

First, special thanks to Jenn Korail of for her help in arranging this interview.

And for the record, Torque News writers have been on top of this one, especially whenever the government readies itself for a new announcement. Read Fuel standards will rise for trucks, buses in 2014 by Hawke Fracassa; and Obama to announce new heavy truck rules today by Don Bain.

Of course, my own coverage of the Scuderi Engine and the Tour split-cycle engines always related to the trucks. Refer to the links below this article.

About the Reporter: After 39 years in the auto industry as a design engineer, Frank Sherosky now trades stocks, futures and writes articles, books and ebooks like, "Perfecting Corporate Character," "Awaken Your Speculator Mind", and "Millennial World Order" via He may be contacted here by email: [email protected]

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