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Lotus Engineering to Showcase Omnivore Engine Concept in Geneva

The Lotus Omnivore engine. Click to enlarge.

Lotus Engineering will display a single-cylinder research engine monoblock demonstrating the architecture of the Omnivore engine concept at the upcoming 79th International Geneva Motor Show. (Earlier post.)

The Omnivore was designed in collaboration with Queen’s University Belfast and Orbital Corporation Limited Australia for high thermal efficiency when fueled on any alcohol-based fuel or gasoline. It features an innovative variable compression ratio system and uses a two-stroke operating cycle with Orbital FlexDI direct fuel injection. It is ideally suited to flex-fuel operation with a higher degree of optimization than is possible with existing four stroke engines, according to Lotus.

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 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.

—Geraint Castleton-White, Head of Powertrain at Lotus Engineering

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

The Orbital FlexDI fuel injection system produces fine in-cylinder fuel preparation irrespective of fuel type, and together with air premixing allows efficient two-stroke combustion and low-temperature starting, while offering singular opportunity for advanced HCCI control.

With sponsorship from DEFRA/DECC and DOE NI through the Renewables Materials LINK program, Lotus Engineering is currently in the final stages of commissioning the Omnivore single-cylinder research engine.



For those who think that variable compression is BS...


And for those that think vehicles need more than one cylinder.
Or more than 2 strokes.
Or that Omnivore should mean more than “any alcohol-based fuel or gasoline” .
Actually variable CR is technically exciting, but so are turbo-compounding and desmodromic valves.


The main thing I like about this is the lack of transparent cutaway. That last MCE5 was positively heathrobinson design.

Not that something so ugly and complicated couldn't work, but aesthetics do have secondary purpose, although the intention is not always achieved.

So Orbital Lotus is a bit of a mistery on the inside and the exterior could be improved beyond recognition with some pink polka dots.
I think It's Caterpillar that have built a six cylinder VCr engine, will try to research that.
Also looked hopelessly complicated (telescoping the cylinders into the crankcase) But they claimed to have it refined 2- 3 years ago.

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