Opposed-piston, two-stroke engines have a fundamental thermodynamic efficiency benefit over four-stroke engines. This was the focus of a recent Achates Power technical paper. Published by the Society of Automotive Engineers (SAE) and presented at last Fall's SAE Commercial Vehicle Engineering Congress, the paper demonstrates that combining the opposed-piston architecture with the two-stroke cycle increased indicated thermal efficiency through a combination of three effects:

• Reduced heat transfer
• Increased ratio of specific heat
• Decreased combustion duration

Read the paper or watch a video overview of the study.

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• CRC 22nd Real World Emissions Workshop
  March 25-28 in San Diego, CA
  Presenting: Superior Cold Start Emissions and Catalyst Light-Off Capability of an Opposed-Piston, Two-Stroke Engine
   
• SAE 2012 High Efficiency IC Engines Symposium
  April 22-23, Detroit, MI
  Presenting: Modernizing the Opposed-Piston Engine for Clean, Efficient Transportation
   
• SAE 2012 World Congress
  April 24-26, Detroit, MI
  Presenting: Cylinder Cooling for Improved Durability on an Opposed-Piston Engine (2012-01-1215)
   
• Emissions 2012
  June 12-13, Ypsilanti, MI