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Opposed-piston engines have been in production since before the 1930’s because of their inherent low heat losses and high thermal efficiency. Now, opposed-piston gasoline compression ignition (OP-GCI) engines are being developed for automotive transportation with stringent emissions targets. Due to the opposed-piston architecture and the absence of a cylinder head, fuel injection requirements and packaging are significantly different than conventional 4-stroke engines with central-mounted injectors. The injection process and spray characteristics are fundamental to achieving a successful combustion system with high efficiency, low emissions, and low combustion noise. In this paper, the fuel injection system for the Achates 2.7L, 3-cylinder OP-GCI engine is described. The fuel system was designed for 1800 bar maximum fuel pressure with two injectors mounted diametrically opposed in each cylinder.

Heavy-duty vehicles, currently the second largest source of fuel consumption and carbon emissions are projected to be fastest growing mode in transportation sector in future. There is a clear need to increase fuel efficiency and lower emissions for these engines. The Opposed-Piston Engine (OP Engine) has the potential to address this growing need. In this paper, results are presented for a 9.8L three-cylinder two-stroke OP Engine that shows the potential of achieving 55% brake thermal efficiency (BTE), while simultaneously satisfying emission targets for tail pipe emissions. The two-stroke OP Engines are inherently more cost effective due to less engine parts. The OP Engine architecture presented in this paper can meet this performance without the use of waste heat recovery systems or turbo-compounding and hence is the most cost effective technology to deliver this level of fuel efficiency.