Lotus Omnivore Engine to be Unveiled at Geneva
Last year Lotus gave us the Lotus Exige 270E Tri-fuel that could run on any mixture of bioethanol, methanol, or gasoline. Lotus continues its endeavors this year with the unveiling of the Omnivore engine that can run on any alcohol based fuel or gasoline.
The Omnivore engine concept features an innovative variable compression ratio system and uses a two-stroke operating cycle with direct injection. The new engine concept is ideally suited to flex-fuel operation with its higher degree of optimization than is possible with current four-stroke engines. This new engine could significantly increase fuel economy with any alcohol-based fuel.
Lotus used a monoblock construction that blends the cylinder head and block together to eliminate the need for a cylinder head gasket. This construction creates a lighter, more durable engine. The Omnivore engine does not require the use of poppet valves like a normal two stroke and this facilitated the application of a monoblock.
“The absence of poppet valves in two-stroke engines makes the incorporation of a variable compression ratio system relatively straightforward,” said Geraint Castleton-White, head of powertrain at Lotus Engineering. He also said that the two-stroke engine design permits a much larger range of compression ratio adjustment, with the potential to perform at a much higher efficiency when running on renewable fuels.
Varying the compression ratio is done using a puck at the top of the combustion chamber. The system varies the compression ratio based on load demands of the engine. The engine also features a sort of variable valve timing that allows for continuous variation of the exhaust opening point. The system allows exhaust timing – in an engine without exhaust valves – and features a charge trapping valve in the exhaust port. The charge trapping valve allows the asymmetric timing of exhaust flow and continuous variation in the exhaust opening point.
Lotus’ aim with this engine is to show sustainable alcohol based fuels have the potential to reduce the overall carbon footprint of internal combustion engines. CEO of Group Lotus plc, Mike Kimberley, is hoping the Omnivore engine concept will help companies (and consumers) embrace alcohol based fuels in the future.