Browse Publications Technical Papers 2017-26-0056

Achieving Bharat Stage VI Emissions Regulations While Improving Fuel Economy with the Opposed-Piston Engine 2017-26-0056

The government of India has decided to implement Bharat Stage VI (BS-VI) emissions standards from April 2020. This requires OEMs to equip their diesel engines with costly after-treatment, EGR systems and higher rail pressure fuel systems. By one estimate, BS-VI engines are expected to be 15 to 20% more expensive than BS-IV engines, while also suffering with 2 to 3 % lower fuel economy. OEMs are looking for solutions to meet the BS-VI emissions standards while still keeping the upfront and operating costs low enough for their products to attract customers; however traditional engine technologies seem to have exhausted the possibilities. Fuel economy improvement technologies applied to traditional 4-stroke engines bring small benefits with large cost penalties.
One promising solution to meet both current, and future, emissions standards with much improved fuel economy at lower cost is the Opposed Piston (OP) engine. Recently, there has been surge in developing highly efficient OP engine architecture to modernize it using today’s analytical tools, high pressure fuel system and manufacturing technologies to meet emissions, while reaping the fuel economy advantage.
As the company pioneering the OP engine technology, Achates Power Inc. (API) has been publishing technical papers in recent years, including a paper describing inherent efficiency benefits of OP engines, multi-cylinder steady state and transient results for medium duty truck and light duty applications. This technical paper provides detailed performance and emissions results measured on API’s 4.9L multi-cylinder OP 2-stroke diesel engine configured specifically to meet BS-VI emissions standards for commercial truck application. The results include:
  • Measured performance and emissions data for emissions test cycles.
  • After-treatment details and confirmation to meet tailpipe emissions for BS-VI standards.
  • Details of API’s multi-cylinder test engine’s indicated thermal efficiency, friction and pumping losses.
  • Comparison with 4-stroke diesel engine.


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