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Offline AshSimmonds

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Lotus Begins 'OMNIVORE' Flex-Fuel Engine Project

Some engine types can run on an endless number of fuels (Chrysler's gas turbine, for instance, was once demonstrated operating on a tank full of tequila), but for whatever reason, most piston engines run - at most - on one or two.  OMNIVORE, Lotus Engineering's latest project, aims to change that.

Partnering with Jaguar and the Queen's University of Belfast, Lotus hopes to create a two-stroke engine that is capable of running on a wide variety of naturally-sourced alcohols (i.e. ethanol or methanol).

Lotus claims the OMNIVORE engine, currently under development, will sport direct fuel injection and a variable compression ratio, potentially allowing for an infinite number of fuel types and sources to be used without any detriment to performance.

As OMNIVORE is primarily a research program, Lotus has no set timetable for placing the engine into production.  To ease development costs, initial prototypes will be single-cylinder units, although the technology, once fully developed, could be adapted for larger engines.


The Lotus Omnivore: A Piston Engine That'll Eat Anything

Lotus Engineering, in collaboration with Jaguar, is starting up a project they're calling "Omnivore," a task which, if successful, could see traditional internal combustion engines go the way of the dodo. Lotus is planning to meld the two-cycle engine with new technologies — direct injection and a variable compression ratio — to create an engine able to run on almost any fuel. If you've ever wondered what the future of the internal combustion looked like, you're getting a peek now. Put your propeller cap on and join us for a pocket protector talk after the jump.

Used to be that a gas engine was a gas engine and a diesel was a diesel. With the advent of reliable direct injection, variable displacement cylinder heads that don't turn into grenades, and incredibly sensitive monitoring and control systems, it's now possible to run an engine in ways would have never worked in the past. Consider the main barrier to high-compression gasoline engines in the past — preignition. High octane numbers were a band-aid for that problem, but that also caused fuel economy to plummet. Direct injection virtually eliminates the issue, allowing engineers to put the fuel right into the chamber exactly when it's needed, high pressure be damned. It's even conceivable to run a gasoline engine on the diesel cycle with direct injection.

Now add the idea of operating with a two-cycle engine to the mix and things get really weird. Two-strokes are traditionally dirty, dirty engines to run. The huge amount of fuel used and inelegant combustion leads to lots of pollution but huge amounts of power, since you've got twice as many power strokes compared to a four-stroke. However, a two-stroke with direct injection and a variable compression ratio would be able to burn almost anything under super-high compression ratios, resulting in temperatures and pressures sufficient to completely burn almost any fuel. Of course, that assumes you can build powerful enough injectors and internal components that don't turn into Swiss cheese in extreme conditions. Let's just say this: Lotus is setting out on a path that's going to get a lot of powertrain engineering PhD's hot and bothered. If they succeed, future car engines will shrink and be more powerful as a result.

Offline flamestone

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capable of running on a wide variety of naturally-sourced alcohols

All sounds very cool.

But surely you'd only run it on the cheap blends and not the good single malts?  :scratchchin:

Offline mondi

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Press Release:

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."

Offline AshSimmonds

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UK: Lotus Omnivore engine shows 10% fuel gains

Lotus Engineering has announced that the initial testing phase of its Omnivore engine development has achieved a 10% improvement in fuel consumption compared to stratified direct injection engines, also with ultra low emissions. The company describes this result as a potential paradigm shift with engine ‘upsizing’ for increased fuel economy.

The first testing phase of the variable compression ratio, flex-fuel direct injection two-stroke engine was successfully completed on gasoline. In addition to the fuel consumption gains, the engine also successfully demonstrated homogenous charge compression ignition (HCCI) - where the engine operates without the need for the spark plug to ignite the fuel and air mixture in the cylinder - down to extremely light loads. This combustion process results in ultra low emissions and was achieved over a wide range of engine operating conditions, even from cold start.

The detailed research has so far focused on lower speed and load conditions that represent a major proportion of an engine’s operation in a real world environment. At 2,000rpm and up to approximately 2.7 bar IMEP (Indicated Mean Effective Pressure), the ISFC (Indicated Specific Fuel Consumption) achieved was approximately 10% better than current spray-guided direct injection, spark ignition engines. Emissions results were 20ppm NOx at less than 2.3 bar load, with four-stroke-equivalent hydrocarbons and carbon monoxide emissions.

Says Simon Wood, technical director of Lotus Engineering: “These impressive results represent an important step-forward in Lotus Engineering’s strategy of developing an array of more efficient multi-fuel combustion systems. Omnivore lays the foundations for a novel and pragmatic vision of a variable compression ratio engine concept suitable for production. A multi-cylinder version is practical for a wide variety of vehicles and offers greatest benefit to C and D class passenger cars which can take advantage of the low cost architecture and significantly improved fuel economy and emissions. We are continuing our discussions with other manufacturers and eagerly anticipate the development of multi-cylinder demonstrations of this revolutionary engine configuration.”

Jamie Turner, chief engineer of powertrain research at Lotus Engineering, also notes: “The automotive industry, including Lotus Engineering, has quite rightly advocated engine downsizing for four-stroke engines. This is as a result of the dominance of the four-stroke cycle in the automotive world and its generation of throttling losses at part-load, where vehicles run most of the time. The twostroke cycle, conversely, does not suffer from significant throttling losses and in many ways is a more natural fit for automotive use. With the thermodynamic disadvantages of throttling losses removed, the two-stroke engine is free to be sized according to its improved part-load fuel consumption. Downsizing therefore isn’t vital and, due to the improved light-load efficiency and emissions performance we see with Omnivore, this technology approach and ‘upsizing’ could permit a more efficient engine.”

The initial Omnivore programme has been in 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. Future work by Lotus Engineering will concentrate on further investigating the operation on gasoline and alternative renewable fuels such as ethanol and methanol, with more in-depth analysis of specific test points.

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