So, was the sleeve-valve engine an evolutionary dead end, as far as the advance of internal combustion?
Let's put it this way. Just like Hollywood likes to recycle old concepts and put a fresh spin on them when it's running low on new ideas, so does the auto industry. Electric cars, you may recall, were a big deal before (ironically) the electric starter made internal combustion cars highly practical. Electrics pretty much vanished from mainstream motoring until environmental concerns brought them back from the grave near the turn of the century.
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].
"This engine technology provides the fuel economy and CO2 emissions of a hybrid at a price that the whole world can afford," Cleeves said in a company-issued statement
Pinnacle says it isn't worried about electric vehicles making its technology obsolete any time soon. Instead, it believes there's a big opportunity to serve rapidly growing markets such as India and China. They and other developing countries want to curb greenhouse gas emissions while improving their citizens' standard of living, through motor vehicle ownership. Since electric vehicles and hybrids still carry a significant price premium, Pinnacle says its re-envisioned sleeve-valve is a good "bridge technology" until electrics become more affordable for everyone.
Pinnacle, which has received several million dollars in venture capital, said it was pursuing a licensing agreement with an Asian auto manufacturer and it expected production to begin in 2013.