Opposed Pistons Offer New, Clean Life for Old Diesel Technology

90 years ago, opposed piston diesels were used for aircraft power plants in applications where high efficiency was essential. Today, the technology may help meet stringent California emissions requirements set for 2027.

Episode Summary:

Internal combustion engines are all about volumetric efficiency. Like all heat engines, higher combustion temperatures mean greater efficiency, but those high combustion chamber temperatures and pressures form an ideal process for creating oxides of nitrogen in the exhaust gas stream. NOx has long been known as a major contributor to photochemical smog, and the state of California has had uniquely stringent NOx emission standards for decades. Upcoming standards set for 2027 appeared impossible to meet, but a test of opposed piston diesel built by Achates Power as part of a CALSTART research project has met the 90 percent reduction requirement without novel exhaust gas aftertreatment technologies. The engine is running in a test truck and promises better fuel efficiency and lower CO2 emissions as a bonus. 

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Written by

James Anderton

Jim Anderton is the Director of Content for ENGINEERING.com. Mr. Anderton was formerly editor of Canadian Metalworking Magazine and has contributed to a wide range of print and on-line publications, including Design Engineering, Canadian Plastics, Service Station and Garage Management, Autovision, and the National Post. He also brings prior industry experience in quality and part design for a Tier One automotive supplier.