The silent sleeve-valve engine
 

https://auto.howstuffworks.com/sleeve-valve-engine.htm
And so, similarly, could the case be unfolding with the slumbering sleeve-valve engine. As the saying goes, "what's old is new again."

San Carlos, Calif.-based Pinnacle Technologies is counting on pent-up demand for clean, cheap transportation in Asia to snap up its modern interpretation of the sleeve valve. A new engine is based on what the company describes as a four-stroke, spark-ignited (SI), opposed-piston, sleeve-valve architecture.

Pinnacle founder Monty Cleeves says his patented engine can yield a 30- to 50-percent efficiency improvement over current internal combustion engines [source: Pinnacle Engines].


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Think I could run to NAPA and grab an engine rebuild kit for that Mors?