Last March at the Geneva Motor Show, Lotus announced its new Omnivore research engine. The Omnivore is a two-stroke direct-injected engine designed to take advantage of the latest in electronic engine management and run on just about any liquid fuel (hence the name). In the time since the initial announcement, the boffins at Lotus Engineering have been exercising their creation on the dyno stand to evaluate its performance.
The single-cylinder engine uses an air-assisted direct injection system. A movable “puck” in the top of the cylinder head allows the compression ratio to be varied.
The engine has so far been run on gasoline in both spark ignition and homogeneous charge compression ignition (HCCI) modes. The HCCI mode is of particular interest because it is capable of providing diesel engine-like efficiency without the particulate and NOx emissions that require expensive after-treatment systems in a standard diesel engine. Lotus is claiming the Omnivore can operate in HCCI mode in a wide variety of operating conditions and even from a cold start, something that has been problematic for previous HCCI engines.
According to the initial test results, the Omnivore is achieving up to a 10 percent improvement in efficiency (as measured by Indicated Specific Fuel Consumption) compared to existing spark ignition direct-injected engines.
There is clearly a lot of work yet to do, but the concept behind Omnivore shows significant promise.