“We’re thrilled to have developed a viable—and affordable—engine solution to significantly improve vehicle mileage without a cost penalty,” said Monty Cleeves, Founder of Pinnacle Engines, at the SAE 2012 World Congress. He was talking about his company's innovative, spark-ignited, twin-crank, 250-cm³ single-cylinder engine developed with an opposed-piston architecture that uses dual-camshaft-actuated reciprocating sleeve valves for induction and exhaust in a traditional four-stroke fashion.
“Due to the cleaner combustion this design allows, our engines can meet rising global emissions standards while maintaining vehicle affordability for developing nations," Cleeves added. "We are excited to bring our first engines to market in 2013 by means of a partnership with a major Asian OEM.” Listen to more of what Cleeves had to say in our video available at this link.
In a technical session Tuesday morning at the 2012 SAE World Congress, Senior Design Engineer, Michael Wilcox, shared more details on how Pinnacle Engines is progressing in the design, build, and test of an opposed-piston engine with a goal of improving real-world vehicle mileage while avoiding additional cost. In its basic configuration at light loads the engine obtained efficiency improvements of 15 to 30% over conventional poppet-valve technology.
Key results include a low surface area-to-volume ratio and cool walls reduce heat loss and improve knock resistance for an efficiency improvement in the gross indicated cycle. At high loads, the engine uses the Cleeves cycle, which results from extremely delayed ignition timing and enables over-compression that does not sacrifice brake mean effective pressure (BMEP) levels with respect to comparison engines.
Though efficiency is reduced from its peak value, the enabled high geometric compression ratio and rapid late-combustion provide sufficient effective expansion to maintain comparable full-load torque and efficiency. Results from methane operation show the potential for additional gains in efficiency as well as flex-fuel operation in the lowest complexity (fixed compression ratio) configuration without compromise to BMEP.