Ever wish you could buy a car that would run on just about anything? An engine that gave you something approaching the efficiency of diesel, and the convenience of gas? Last week, the forward-thinkers at Lotus announced just that.
It’s called the Lotus Omnivore, and we’ve got all the details on this little, all-aluminum marvel.
From the first use of aerodynamic ground-effect on Formula 1 race-cars, to pioneering the use of extruded aluminum for lightweight automotive construction, Lotus has been at the forefront of automotive innovation for almost 50 years.
We’ve covered Lotus’ a bit of innovative history and involvement in Chrysler’s ENVI electric vehicle program before, but this release might the public’s first glimpse of the innovation new technology behind the revolutionary hybrid this Financial Times article says Lotus will be revealing at next month’s Geneva show.
Called the Omnivore, this new kind of engine takes aspects of a conventional 2-stroke, and adds a few neat tricks to that proven technology to create an engine truly flexible enough to run on almost anything, from 87 Octane to Cabo tequila to VP Nitromethane.
Omnivore – Neat trick no. 1: variable-compression ratio
Unlike conventional 2 and 4-cycle engines, the Omnivore’s control software can actually alter the engine’s compression ratio (the value that represents the ratio of the volume of its combustion chamber - from its largest capacity to its smallest capacity) to take advantage of alcohol’s higher octane (which allows for a greater degree of compression prior to detonation when compared to gasoline).
Omnivore – Neat trick no. 2: Mono-block construction
As innovative as the engineers at Lotus are, they’re not above copying a good idea. One of the biggest obstacles to Lotus’ dominance in American open-wheel racing (think “1960′s Indy 500″) was the Offenhauser engine company, which manufactured its “Offy” engines (shown, above) with “unit construction” until 1983, when the turbo 4-cylinder engines were eventually legislated out of competition. The Offy’s unit construction meant there was no separate cylinder head (the engine’s cylinders were milled from a solid block of aluminum – the pistons, cams, etc. were dropped in from the bottom) allowing for tremendous compression ratios, high-boost turbochargers, and cool high-rpm running that took advantage of alcohol-based fuels more than 60 years ago.
SO, like the old Offy turbos, Lotus’ Omnivore does not have to worry about excessive turbo boost or compression damaging head gaskets or piston seals – there simply aren’t any!
For more on the Lotus Omnivore, see the official press release is pasted below:
PRESS RELEASE
Lotus Omnivore Research Engine Unveiled
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 FlexDI™ 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.”
Image Credits: Omnivore engine – Lotus Cars; Offy courtesy of Wake Me When Its Over under a Creative Commons license.
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About Jo Borras
From you description of the Miller/Offy/Meyer-Drake, it is obvious that you have never dis-assembled one of these engines, or had one spread out on the bench before you in its’ dis-assembled state.
From you description of the Miller/Offy/Meyer-Drake, it is obvious that you have never dis-assembled one of these engines, or had one spread out on the bench before you in its’ dis-assembled state.
@AD
So very true – and it is one of the great tragedies of my life! If you have access to such a machine, I would be grateful for the chance to see it torn down.
@AD
So very true – and it is one of the great tragedies of my life! If you have access to such a machine, I would be grateful for the chance to see it torn down.
-RE: integrated cylinder heads. If memory serves the Bristol Corp. in the UK built their WW2 sleeve valve radial aircraft engines with one piece cylinders. The absence of valves made it a logical manufacturing step.
-How does Lotus vary the compression ratio?
-RE: integrated cylinder heads. If memory serves the Bristol Corp. in the UK built their WW2 sleeve valve radial aircraft engines with one piece cylinders. The absence of valves made it a logical manufacturing step.
-How does Lotus vary the compression ratio?
“the pistons, cams, etc. were dropped in from the bottom)”
How in the world can a cam be fitted from the bottom of the engine? Its bigger than the piston
“or piston seals – there simply aren’t any!”
Really? No piston rings? How is that possible?
And while getting rid of the head gasket is great, what seals the variable compression ration “puck” against the top of the combustion chamber?
Does the two stroke mode mean that the crank is not bathed in oil?
“the pistons, cams, etc. were dropped in from the bottom)”
How in the world can a cam be fitted from the bottom of the engine? Its bigger than the piston
“or piston seals – there simply aren’t any!”
Really? No piston rings? How is that possible?
And while getting rid of the head gasket is great, what seals the variable compression ration “puck” against the top of the combustion chamber?
Does the two stroke mode mean that the crank is not bathed in oil?
A cam can be worked into a motor in several ways – I’ve never torn down an Offy (just seen the ones on display at Indy and in a few old textbooks YEARS ago). Also note, on an OHV motor the cams are located more closely to the “bottom” of an engine.
I think the 2-stroke mode at least implies that there is no oil pan or sump for the crank. The drawings from Lotus got “edited out” for some reason, but you can find them here http://gas2.org/files/2009/02/lotus-omnivore-engine.jpg
A cam can be worked into a motor in several ways – I’ve never torn down an Offy (just seen the ones on display at Indy and in a few old textbooks YEARS ago). Also note, on an OHV motor the cams are located more closely to the “bottom” of an engine.
I think the 2-stroke mode at least implies that there is no oil pan or sump for the crank. The drawings from Lotus got “edited out” for some reason, but you can find them here http://gas2.org/files/2009/02/lotus-omnivore-engine.jpg
No “piston seals”?
No “piston seals”?
Great idea on the Lotus Omnivore, but why did you have to bring up the Offy? This has opened an old wound, as I – not coincidentally – quit watching Indy Car racing back in ’83. Sorry, but without that Offy turbo whine, IT ISN’T INDY CAR RACING!
zzzzzzzZZZZZZZZZzzzzzzzz…
I miss it.
Of course, on a larger scale, ALL AUTO RACING is boring now, as the cars are all legislated to be the same in the name of fairness, safety, and cost (Is there ANYTHING IN THE WORLD a lawyer can’t ruin?): NASCAR, Indy Car, and now F1. Boring as all get out when compared to, oh let’s see, Can Am racing, where the object was to engineer a winner and the rules were “run whatcha brung.” Vacuum fans for ground effects? Why, yes, that will be fine. Variable pitch wings attached to the rear suspension? Oh, sure, cool. Ground effect skirts that actually touch the macadam? Groovy, baby! THAT was real – and engrossingly interesting – auto racing.
But, I digress…
Great idea on the Lotus Omnivore, but why did you have to bring up the Offy? This has opened an old wound, as I – not coincidentally – quit watching Indy Car racing back in ’83. Sorry, but without that Offy turbo whine, IT ISN’T INDY CAR RACING!
zzzzzzzZZZZZZZZZzzzzzzzz…
I miss it.
Of course, on a larger scale, ALL AUTO RACING is boring now, as the cars are all legislated to be the same in the name of fairness, safety, and cost (Is there ANYTHING IN THE WORLD a lawyer can’t ruin?): NASCAR, Indy Car, and now F1. Boring as all get out when compared to, oh let’s see, Can Am racing, where the object was to engineer a winner and the rules were “run whatcha brung.” Vacuum fans for ground effects? Why, yes, that will be fine. Variable pitch wings attached to the rear suspension? Oh, sure, cool. Ground effect skirts that actually touch the macadam? Groovy, baby! THAT was real – and engrossingly interesting – auto racing.
But, I digress…
@Hucbald
The best racing in the world right now is in “Unlimited Outlaw” oval-track karting. Fans, wings, variable aero, etc. All there, complete with old Can-am guys and their grandkids.
@Hucbald
The best racing in the world right now is in “Unlimited Outlaw” oval-track karting. Fans, wings, variable aero, etc. All there, complete with old Can-am guys and their grandkids.
@Para
No idea … must have made sense to me when I wrote it? Or, like my original title (“I’m not drunk, officer – but my car is blowing a .23!”), the intended meaning was somehow edited out.
@Para
No idea … must have made sense to me when I wrote it? Or, like my original title (“I’m not drunk, officer – but my car is blowing a .23!”), the intended meaning was somehow edited out.
There have been many attempts to design an electric powered vehicle for as long as the the internal combustion engine has been around. Unfortunately, battery power was never a formidable contender to the present internal combustion engine, but it looks as though it is time for change.
The Electric Vehicle, is It the Answer?
There have been many attempts to design an electric powered vehicle for as long as the the internal combustion engine has been around. Unfortunately, battery power was never a formidable contender to the present internal combustion engine, but it looks as though it is time for change.
The Electric Vehicle, is It the Answer?
There have been many attempts to design an electric powered vehicle for as long as the the internal combustion engine has been around. Unfortunately, battery power was never a formidable contender to the present internal combustion engine, but it looks as though it is time for change.
The Electric Vehicle, is It the Answer?
Sounds intriguing, while I’m not a big sports car fan I’ll have to see what the end application is for this design.
Sounds intriguing, while I’m not a big sports car fan I’ll have to see what the end application is for this design.