Lotus Omnivore Flex-Fuel Engine Concept Unveiled Ahead of Geneva

Lotus has taken a different approach on alternative fuel technologies with the Omnivore engine concept. While set to debut at the Geneva Show, Lotus just couldn't resist giving us a glimpse of its latest creation.

The Omnivore engine is unique in that it will run quite happily on standard petrol or alcohol-based fuels. This ability to devour both types of fuel lends the Omnivore its name and sounds so much cooler than, say, 'hybrid' (ok, we know it doesn't have an electric motor).

Lotus will display the single-cylinder mono-block unit at the Geneva Motor Show next week. Among its claims, Lotus says that the engine has been designed for high thermal efficiency regardless of fuel type used. This is an important aspect to note as much of the energy a combustion engine produces is lost as heat.

A variable compression rate also means the two-stroke mill can operate at peak efficiency throughout the rev range. The absence of poppet valves allows the variable compression system to be implemented with greater ease than on a conventional two-stroke engine. The design of the block is such that no cylinder-head gasket is required, meaning less weight and greater durability.

It's very interesting technology and could pave the way for a new range of vehicles powered by a low to zero emissions renewable energy source.

We’ll bring you more information when the engine debuts in Geneva but for now you can obtain further details from the press release below.

Lotus reveals flex-fuel engine concept to maximise fuel efficiency when running on renewable fuels or gasoline.

Lotus Engineering, the world-renowned automotive consultancy division of Lotus Cars Limited, unveils its latest research into engine efficiency at the 79th International Geneva Motor Show. The Omnivore engine concept has the potential to significantly increase fuel efficiency for sustainable alcohol based fuels, which increases the prospect of a greater amount of vehicle miles travelled using renewable fuels. On display will be the single cylinder research engine monoblock that demonstrates the novel architecture designed for high thermal efficiency when fuelled on any alcohol based fuel or gasoline.

The Omnivore concept features an innovative variable compression ratio system and uses a two-stroke operating cycle with direct fuel injection. It is ideally suited to flex-fuel operation with a higher degree of optimisation than is possible with existing four stroke engines.

The engine concept features a monoblock construction that blends the cylinder head and block together eliminating the need for a cylinder head gasket, improving durability and reducing weight. In this case, the application of a monoblock is facilitated by the absence of the requirement for poppet valves. A novel charge trapping valve in the exhaust port allows asymmetric timing of exhaust flow and continuous variation of the exhaust opening point.

The variable compression ratio is achieved by the use of a puck at the top of the combustion chamber. This simple, yet effective system moves up and down affecting the change in geometric compression depending on the load demands on the engine.

Mike Kimberley, Chief Executive Officer of Group Lotus plc said: "We are delighted to unveil this major milestone in the development of an engine configuration for a new breed of more efficient multi-fuel engines. The automotive sector is focusing on its environmental obligations to improve efficiency, minimise reliance on fossil fuels and reduce harmful emissions and Lotus continues to be an industry leader through our work on all aspects of future fuels. Sustainable alcohol based fuels have the potential to reduce the overall CO2 footprint of internal combustion engines towards zero and for this reason, need to be embraced as future fuels for road transport."

In this collaboration with Queen's University Belfast and Orbital Corporation Limited Australia, with sponsorship from DEFRA/DECC and DOE NI through the Renewables Materials LINK programme, Lotus Engineering is currently in the final stages of commissioning the Omnivore single-cylinder research engine. It uses the Orbital FlexDITM fuel injection system which produces fine in-cylinder fuel preparation irrespective of fuel type, and together with air pre-mixing allows efficient two-stroke combustion and low-temperature starting, whilst offering singular opportunity for advanced HCCI control.

The Omnivore programme is another development of Lotus' research into understanding the complex combustion processes involved in running an engine on mixtures of alcohol based fuels and gasoline, which included the Lotus Exige 270E Tri-fuel, unveiled at the International Geneva Motor Show in 2008. This research is vitally important for a successful transition from today's fuels to the more efficient sustainable fuels of the future.

Geraint Castleton-White, Head of Powertrain at Lotus Engineering said, "The absence of poppet valves in two-stroke engines makes the incorporation of a variable compression ratio system relatively straightforward. Our research into these systems on four-stroke engines has led us to the conclusion that while thermodynamically it is a desirable technology to incorporate, practically it is very difficult, particularly taking into consideration production feasibility. This two-stroke engine could solve these practical difficulties and simultaneously permits a much larger range of compression ratio adjustment, with the potential to perform at a much higher efficiency when running on renewable fuels."