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Efficient Engine Design

Achates Power
ARPA-E Award: 
San Diego, CA
Project Term: 
04/01/2016 to 07/13/2019
Project Status: 
Technical Categories: 
Critical Need: 

More than 25% of all the energy consumed in the United States is used in transportation, with the majority of that consumed in cars and trucks. Improved powertrain systems and engine technologies can enable more efficient and cleaner vehicles. While their efficiency has steadily advanced in recent decades, current engines cannot cost effectively achieve the efficiencies needed to significantly increase vehicle fuel economy. New and novel approaches are needed to spur transformational increases in vehicle powertrain efficiency. The combination of opposed-piston (OP) and gasoline compression ignition (GCI) technologies has the potential to overcome current cost and efficiency challenges and significantly advance engine technologies for decades to come.

Project Innovation + Advantages: 

The team led by Achates Power will develop an internal combustion engine that combines two promising engine technologies: an opposed-piston (OP) engine configuration and gasoline compression ignition (GCI). Compression ignition OP engines are inherently more efficient than existing spark-ignited 4-stroke engines (potentially up to 50% higher thermal efficiency using gasoline) while providing comparable power and torque, and showing the potential to meet future tailpipe emissions standards. GCI uses gasoline or gasoline-like fuels in a compression ignition engine to deliver thermal efficiency on par with diesel combustion. However, unlike conventional diesel engines, this technology does not require the added expense of high-pressure fuel injection equipment and sophisticated aftertreatment systems. The OP/GCI engine technology is adaptable to a range of engine configurations and can be used in all types of passenger vehicles and light trucks. By successfully combining the highly fuel efficient architecture of the OP engine with the ultra-low emissions GCI technology, the resulting engine could be transformational, significantly reducing U.S. petroleum consumption and carbon dioxide.

Potential Impact: 

Achates Power will design and demonstrate a more efficient engine that, if successful, will significantly reduce petroleum consumption and carbon dioxide emissions in the United States.


The new engine design will have better fuel economy, which could reduce the demand for imported oil.


This technology has the potential to reduce CO2, nitrogen oxides, and particulate matter emissions from vehicles, helping to improve air quality.


This team's engine design could be extremely cost effective and will allow for greater vehicle fuel efficiency at a competitive cost.

Innovation Update: 

(As of May 2018)

The Achates Power team successfully integrated a GCI combustion strategy with an OP engine architecture to create an innovative, high-efficiency gasoline engine. Researchers at ANL, Achates, and Delphi conducted simulations and studies under varying parameters, such as compression ratio, to achieve optimum design. The resulting OP-GCI engine is a 2.7 liter with a 270 horsepower rating with initial results showing thermal efficiencies between 45-50%.


Cost modeling studies project the team’s OP-CGI technology will cost less than current technology trajectories starting in 2025, at which point OP-CGI engines could penetrate the light- and heavy-duty engine market. The technology has garnered interest from the defense, automotive, marine, and oil and gas industries. Notably, the team has received follow-on funding from the Oil and Gas Climate Initiative, a CEO-led initiative of ten oil and gas companies, to further develop and commercialize the technology.


For a detailed assessment of the Achates project and impact, please click here.


ARPA-E Program Director: 
Dr. Christopher Atkinson
Project Contact: 
Mr. Fabien Redon
Argonne National Laboratory
Release Date: