Lotus Updates Efficiency Gains on its Flex-Fuel Omnivore Engine
Although admittedly still early in the development process, Lotus Engineering has released new test data on its experimental Omnivore engine and the results look quite promising. Designed to operate on a wide range of petroleum-based and biofuel-based fuels, the Omnivore is a two-stroke, direct-injected design capable of varying its compression ratio from 10:1 to 40:1. That characteristic permits it to function as a de facto high-efficiency diesel that doesn't require the use of a conventional spark plug and delivers substantially better economy with lower emissions. The tests, performed with the engine burning gasoline, showed that in addition to achieving approximately 10 percent better Indicated Specific Fuel Consumption (ISCF) values than a conventional direct-injected counterpart, the Omnivore also produced lower oxides of nitrogen (NOx) than a four-stroke equivalent with similar hydrocarbon (HC) and carbon monoxide (CO) emissions. Equally important, Lotus says it has managed to get the Omnivore to function in its diesel-like mode -- technically called HCCI for "homogenous charge compression ignition" -- under extremely light load conditions. Although several automakers are currently exploring the potential of similar HCCI engines, the ability to make them operate as efficiently under light and/or heavy load conditions as they do in less-demanding mid-range situations has proven to be one of the key challenges to be overcome before this type of next-gen internal combustion engine can ever transition from experimental to production-ready status.