Inverted engines, where the crankshaft is placed above the cylinders, are nothing new. Piston aircraft have been using upside down engine designs for the better part of a century. By placing the cylinders and heads below the crankcase you can raise the mounting point of the propeller considerably while lowering the height of the cowling. You get better ground clearance via the higher prop and better visibility with the lower cowl, if the engine is forward of the cockpit. You also shift the centre of gravity considerably, which can aid handling in combat and aerobatic aircraft.

Certain wartime designs used armaments as their excuse for an inverted design – the inverted Daimler-Benz DB600-series V-12 allowed the placement of a 20mm cannon within the centre of the propeller shaft. A reduction gear was used so the prop was below the crank, allowing the placement of the cannon in the vee of the engine to fire through the hollow propshaft. This left room above the crankcase for two additional machine guns.

An inverted engine has only been installed into a motorcycle once before. A 600cc inverted inline-four was built as a prototype by French company MGC in 1939, with the engine mounted longitudinally in the frame. It covered a mere (and ominous) 666 kms of testing with a sidecar before being mothballed - history intervened and the outbreak of the Second World War put the project on hold, never to be resumed.

Building an upside down engine isn’t as simple as flipping over an existing motor ( though that has been done on occasion ). A series of modifications are required to keep the motor lubricated. All inverted engines need to be dry sump designs, where the oil is held in a separate tank and fed to key lubrication points in the engine. Multiple oil pickups need to be placed in key locations within the engine to scavenge the oil without allowing it to pool in crevices. The cylinders need to be cast separately from the block and have significant liner protrusions within the crankcase, so that oil will pool around them, not pour into them.Some older radial engines need to be checked and have their lower cylinders drained of oil before starting due to oil seeping past the pistons – if not, you risk blowing up the motor by hydrolocking the cylinders.

In addition to unique lubrication considerations, the intake system of an inverted engine needs to be designed to accommodate the upside down combustion chambers.

So an inverted engine makes sense in prop-driven aircraft design - but why use it in a motorcycle? According to Sabatini, the reason is twofold: structural and aesthetic. The crankcases of an engine are the most rigid part of the structure – if you are using the engine as a stressed member, you generally want to bolt the chassis to the crankcase. If you use the heads, which are more conveniently placed up high, you need to reinforce them considerably. Sabatini wanted to get the best of both – with the crankcase up top, he could exploit the inherent rigidity of the crankcases and build a minimal frame around them. He could also radically alter the centre of gravity of the machine - contrary to popular belief, having an extremely low centre of gravity is not the ideal and today's thought runs towards mass, rather than lowering the CG. A bonus effect is that the cylinders are better exposed to air flow - the engine runs cooler and the rider won't get cooked.

The second consideration was purely cosmetic. Sabatini lamented the passing of the classic beauty of an exposed, air-cooled engine in favour of shrouded liquid-cooled designs. Thus the Nembo engine is designed to be A. air-cooled and B. beautiful. This aesthetic desire extends into the design of the motorcycle itself – only a naked roadster would suit Sabatini’s desire for classic mechanical beauty, with his unusual engine as the centrepiece.

Bleeding edge high performance engine design... is clearly not the point of the exercise. Aside from being air/oil-cooled, the Nembo engine is an inline triple with a single “underhead” cam and two valves per cylinder. It is fuel injected, but via a large intake plenum with a single throttle body like an automotive engine instead of the individual throttle bodies you’ll usually find on most performance-oriented motorcycle engines. Maximum volumetric efficiency and high-rpm power isn't the aim - a broad, usable spread of power for the street is. The engine makes loads of power across the board simply by virtue of being so damned huge - there ain't no substitute for cubic inches, and the Nembo makes plenty of power while remaining relatively unstressed. The claimed torque range from a stout 119 lb/ft for the 1814cc engine, and a staggering 177 lb/ft for the 2097cc version. For comparison, the 2294cc Triumph Rocket III triple makes about 145hp and just over 160 lb/ft. It also weighs 700 pounds...

Aside from being upside down, the cylinder heads are alsofrom traditional bike design – the intake is at the front, the exhaust at the rear. The exposed plenum is set into the flow of oncoming air which keeps the intake components from getting heat soaked. Cylinders are individually jacketed with fine cooling fins and are reminiscent of one half an air-cooled Porsche flat-six when viewed from the front. The engine cases are sandcast with milled billet covers and a massive timing chain housing on the left side – the result looks remarkably like an upside down AJS 7R engine, which is to say quite striking. There is no denying the visual appeal of the design, and it is refreshing to see someone build an engine that is deliberately, not incidentally, beautiful.

In the initial press release three projected displacements were announced. All three would share the same 77mm stroke, with different bores. The smallest would be 1814cc via a 100mm bore and would knock out 160hp, the next would be 1925cc via 103mm and would make 200hp, and the big boy of the range would displace 2097cc with a 107.5mm bore and make a stout 250hp. Impressive stuff, especially considering they claim the engine will be Euro 3 emissions compliantthe complete bike weighs 350lbs dry. Even the “small” 1800 version would have a near 1:1 horsepower : kilogram power-to-weight ratio. The low weight was due to a relatively light engine (190 odd pounds on its own – featherweight for something displacing 1800 plus ccs) bolted into a light chassis with simple bodywork and a slathering of high tech materials to keep the poundage to a minimum.

The project began in 2009 and surfaced online in 2010 as photos of a completed engine on a test bench with an accompanying press release and spec sheet from Sabatini that detailed his philosophy and the technical data of his new motor, which he dubbed the 32 Rovescio (3 cylinder, 2 litre, reversed). The public was impressed, but sceptical. Few outside the aircraft industry were even familiar with inverted engines, and doubted it could even run. Other skeptics claimed it might run, but it would burn oil at a ridiculous rate and offered no advantages over a conventional engine. Most doubted the projected power and weight specifications, which seemed optimistic if not improbable for an air-cooled single-cam engine. The most common response was “”.

Criticism faded when photos of a complete prototype were shown a few months later. The bike looked menacing with bare carbon-fibre bodywork and the positively massive engine dominating the design. Up front was a conventional suspension with 50mm upside down forks and, oddly, a single Brembo brake. Rear suspension featured a springless air shock (similar to the Vyrus and Bimota Tesi 2D ) attached to a carbon-fibre box-section swingarm. The frame was composed of two steel trellis subframes bolted to either end of the crankcases - the main mass of the frame is effectively the engine, with minimal subframes for the seat and steering head. The prototype was photographed, appropriately, in front of an air-cooled aircraft radial engine.

However it appeared that the Nembo wasn’t yet ready for prime time. The prototype was shown without a complete exhaust, and had no drive chain. No street equipment was present, and it had a half-finished look to it. Again the critics doubted it would work. Yes, we have the trappings of a motorcycle bolted around this crazy engine, but no one had witnessed it running or moving under its own power.

The critics were finally silenced in July 2011 when the Nembo made an appearance at the Franciacorta circuit for track testing. A bright, Italian red 1814cc prototype (the second built) burst into life in the paddocks with a throaty racket that can only be described as the bastard offspring of a Triumph triple and a Bristol radial. At low revs it had the signature mechanical whir of a British triple, while under load it sounded like a low-flying aircraft blasting across the track with a staccato bellow . The test rider praised the unusual design, reporting it had tidy handling, a broad spread of power, and an utterly magnificent sound. Apparently Sabatini’s venture wasn’t all vapourware – the proof was roaring around the track, attracting curious onlookers in the pitlane. The Nembo was present to tune the fuel injection and dial in the engine, with additional testing at the Adria circuit in the fall of 2011.

The engine dominates the design, appearing massive in relation the other components. The swingarm is quite long relative to the rest of the machine, and pivots high in the engine cases by necessity – the countershaft sprocket sits at knee level due to the placement of the gearbox on top of the engine. The result looks like a strange amalgam that appears incongruous but purposeful – it looks like someone stuffed a GSXR-1100 engine into a dirtbike chassis. The hidden frame and minimal bodywork contributes to this all-motor appearance, as does the tiny tailsection and seat perched high above the rear wheel. Some make comparisons to café-racers, but I’d be more inclined to describe it as a brutish hand-built streetfighter.

Despite making its maiden voyage on the track, the Nembo is not intended to be a race machine. It was designed to be a high performance street bruiser that was to be built to order in street-legal trim – or at least that was the plan in 2011. Since then news from the company has been nonexistent and their website inactive. The last public outing was the showing of the red track prototype at the 2012 Concourso d'Eleganza di Villa d'Este in Cernobbio, Italy. Retail pricing was never announced publicly but was anticipated to be exorbitant based on the hand-built nature of the design.

While the others are rather 'assemblers', Nembo Motociclette can rightfully claim the title of true 'builder manufacturer'

Image Source

The Nembo is a weird offshoot on the motorcycle evolutionary tree. It's unlikely to be a breakthrough that will influence mainstream design, nor will designers clamor to build inverted engines now that the trail has been blazed. The benefits of such a design are offset by the added complexity of designing a motor from scratch.

Daniele Sabatini and his creation.

Image Source

Image Courtesy Nembo Motociclette

Nembo Motociclette



The 32. Young and already legendary:







Cars and motorcycles can be only means of transport, or wonderful toys that give to men, of character and good taste, sensations without equal.







We can say that cars and motorcycles are only means of transport, maybe very advanced and highly performing, when they are produced in assembly lines, all the same and aseptic, while they are “different”, solid dreams for few, when they have been built slowly, handcrafted with love and with the best technologies and materials, in few, very rare pieces, made to order.



When a motorcycle is part of the second category, it has a value added since no car will ever give the sensations that an extraordinary motorcycle can give.



It’s a different kind of luxury, that maybe you can succeed in buying, but if you do not have a finely educated taste, you could not even understand it. And his temper could slip away through your fingers.



Nembo Motociclette created the 32 for those few lucky people who will succeed to get it and understand it. The 32 is not only the most expensive road sport-motorcycle in the world, is an erotic mechanic dream, and its lines will remain beautiful and desirable forever, in spite of the passing of time.



No motorcycle is like the Nembo 32. For most people, the roar of its mighty two thousand cubic centimeters tricilindrico engine will echo like a thunder through the decades just in the videos on the web, but for the man who will ride this bike, that thunder will become part of their heartbeats.



It 's just two years ago, at the end of 2010, when Nembo introduced a mock-up prototype of the 32 in a motorcycle blog (Ottonero) and made a great stir, in motorcycles magazines, blogs and forums. That happens only with the new models introduced by the leading motorcycle manufacturers and after a huge media hype. Nembo Motociclette has done virtually nothing to promote its 32, however, one year after the showing of the first prototype video in its first track test, is already one of the most desired sport-bike of the planet and according to many, the only real new big thing in the motorcycle world since many years.





Although Nembo has not yet submitted the final model, the "series" model, even if the term "series" is not part of our vocabulary.







A true revolution.







Many make handcrafted motorcycles today, selling them at very high prices and defining themselves "builders". However, none of them directly builds and develops its own engine , like Nembo does with its "Super 32 Rovescio," everyone else rather uses simple series engines purchased from others for a few thousand Euros.



That’s the watershed that divides the 32 from all the others.



Nembo has in fact its own engine, in-house designed, built and developed at the cost of considerable investment and a huge engineering and business effort. While the others are rather "assemblers", Nembo Motociclette can rightfully claim the title of true "builder manufacturer".







But if having created a new extraordinary motorcycle with its own motor is the dream, "invert" this engine to demonstrate a revolutionary dynamic and aesthetic concept, that’s already in the history of motorcycling, is the sublimation of this dream. You can imagine the value of one of the two extremely rare 1814 cubic centimeters prototypes in twenty or thirty years. Or imagine the value of the following 2000cc models too.



Facts:



Nembo Motociclette is a new small Italian motorcycle company based in Rome, Italy. It’s leaded by Daniele Sabatini, only owner and chief designer.







The first project of the Nembo Motociclette started in mid of 2009 to create totally new "naked" sport-bike from empty sheet. The result was the type "32" (i.e., 3-cylinder / 2 liters): the first and only motorcycle in the world to mount an engine inverted (or upside down) with the block that replaces the frame and where heads and cylinders are not involved in the structural function (patented innovation).



The production consists of top-end sports motorcycles, for road and track, equipped with in-house designed and manufactured engines. Even the frames, the swingarms, the tanks, the bodywork and the most of the components are designed and constructed in-house handcrafted and made with CAD/CAM precision machinery. Only wheels, front suspension, brakes and electronics are from third-party suppliers of global significance.



Manufacturing technologies are highly sophisticated and components are similar in sophistication to the standards of MotoGP bikes.



The bikes are built only to order and accurately assembled by hand.



The 32 has been designed to demonstrate a revolutionary concept in the true sense of the word: for making a motorcycle with a larger displacement engine that is fast, small, lightweight and easy to handle, it is necessary to invert the engine, i.e. install it on the bike “upside-down if compared to the traditional scheme. Only by that, we can reach the extreme mass-centralization to give to the bike an extraordinary dynamic behavior.





Only with this particular architecture enables the use of large displacement engines on a motorcycle which has the size and the weight of a 600cc or 1000 cc current sport-bike.



The 32 is designed to mount 2 liters motors, for dry-weighing, just 160 kg, to have a wheel base of only 1450 mm, while being equipped with a very long swing-arm, 680 mm axle to axle, almost half of the bike. To achieve these extraordinary goals, Nembo Motociclette had to develop and build its own engine: a new three-cylinders, four-stroke, in-line, called the "Super 32 Rovescio." The major element of novelty of this engine is mainly in the fact that works upside down, ie with heads and cylinders placed under the crankshaft.





The inverted inline engines are not new in the history of the engines. Indeed they are a very important element in it. De Havilland, Daimler-Benz and Junkers, for example, built hundreds thousands of them, in the thirties and forties, such as aircraft engines. In particular, the inverted in-line engines powered most of the German fighter aircraft used in World War II. Even the aircraft radial engines have half of the cylinders inverted and were also mass produced during World War II, serving until the sixties in the military and civilians air forces from around the world.





Nor we can say that these engines are new in the history of the motorcycle, as in 1939, a french motorcycle, the 600cc MGC was equipped with an inverted in-line engine. It had, however, a totally different architecture compared to the 32: in fact, the engine did not work as a frame and had its 4-cylinders placed on the longitudinal axis of the bike. It was built and tested, but the project ended because of the war.

The engine Nembo "Super 32 Rovescio" is the first engine in the history designed and built to work as a frame with the crankcase transversal to the motorcycle longitudinal axis. Moreover it’s the first inverted engine ever in the world can meet and exceed 8500 rpm, thanks to its innovative lubrication system. The previous inverted engines could reach just 4500 rpm. It’s also the first inverted motorcycle engine in which the block is the only cross-link between the steering head and swingarm and where the heads and cylinders are not involved in structural work.



The "Super 32 Rovescio" engine is also a very small to be a 2 liters three-cylinders. It’s even more compact and short of most of the current 1000cc three / four cylinders traditional engines. Also for this reason, the bike can be equipped with a very long carbon fiber 680 mm, axle to axle, swingarm, that allows excellent stability and great traction.



The displacement chosen for the "Super 32 Rovescio" engine is two liters, because unlike a 1000cc current engine, a 2-liter engine is capable of delivering more power and torque in a more gentle way at the low revs too, making driving the 32 fun, relaxing and "friendly" even for non-experts. However, it’s very powerful and installed on a so lightweight and agile bike, allows terrific performance and extraordinary feelings, never felt before with any traditional 600 or 1000 sport motorcycle.



The 32 is not designed to be a faired track motorcycle, it is quite a sport-naked made for fun, both on the road and on the track. Its natural habitat are the bends. But, besides being very funny, is more comfortable than a traditional superbike as the heat generated by heads and cylinders is located at the bottom of the engine, so not between the rider's legs.



Nevertheless, in the near future, competition models will be built, with adequate engines capacities, our hope is to compete at the Tourist Trophy race on the Isle of Man within a three years.



On October 2010 the upside down engine was assembled for the first time. At the end of 2010 was made the first check dry assembly with the real components of the bike. In July 2011 the first prototype was on the Franciacorta track of in a first test session for the dynamic tests. In October 2011, he performed his second test session on the Adria track at for a medium revs engine tune-up

Tests have shown the validity of the original concept based on the inverted engine: superior handling in the bends, great balance, excellent dynamic behavior.

The first two prototypes, the 001 and the 002, are the only 32 with the engine from 1814cc. From 003, the first production model for sale, all the engines will be 2000 cc.



On May 2012, the 32 has been selected by the BMW Group / BMW Classic to attend the famous Concorso d'Eleganza Villa d'Este 2012 at Cernobbio on Lake of Como Concorso d'Eleganza di Villa d'Este

Production model specifications:

Frame: aluminum billet crankcase, connected to the steering hub by a Cr-Mo steel or aluminum hand welded and CNC machined or carbon fiber layered by hand and vacuum molded body autoclave treated sub-frame.

Seat frame: Cr-Mo steel Seat sub-frame welded by hand or carbon fiber body layered by hand and vacuum molded body autoclave treated. Ancillary frame components made of billet aluminum and CNC machining.

Swing-arm: double-layered carbon fiber arms by hand and vacuum molded body treated in an autoclave. with elements from billet CNC machined aluminum, variable length mm 670/690, pivoted directly onto the engine block

Front wheel, five-spoke 17 x 3.5 carbon fiber hand layered and vacuum molded body treated in an autoclave.

Rear wheel rim, five spokes 17 x 6.0 carbon fiber hand layered and vacuum molded body treated in an autoclave.

Front tire: 120/70 ZR 17

Rear tire: 190/55 ZR 17 or 200/55 ZR 17

Front suspension: 50 mm telescopic fork USD

Rear suspension: prototype air monoshock by Double System / Silvano Bellapadrona expressly for Nembo, CNC machined from billet aluminum

Front brakes: two 320mm floating Brembo T-drive discs. Brembo radial calipers

Rear brake: 220mm single disc, two-piston radial caliper Brembo

Seat height: 80/86 mm, adjustable

Wheelbase: 1450mm (with 680mm swing-arm)

Dry weight: 160 Kg

Fuel tank: 12 liters. Aluminum hand welded tank

Oil tank: 4 liters. Aluminum hand welded tank

Body: carbon fiber hand layered and vacuum molded tilting body treated in an autoclave. "Super 32 Rovescio" production engine specifications:



Dimensions:

Maximum width: 480 mm

Maximum height: 480 mm

Maximum length: 420 mm Type: Inverted - 4 stroke - 3 cylinder



Bore: 103 [mm]

Stroke: 77 [mm]

Displacement: 1925 [cc] - 117.47 cubic inches

Compression ratio: 11.5: 1

Distribution: SUHC - single under head camshaft) driven by chain and gears

Number of valves: 2 per cylinder

Cooling system: air / oil

Lubrication system: Dry sump with double rotor scavenge pump

Clutch: oil bath

Transmission: 6-speed

Maximum power: 200 [bhp] @ 7500 [rpm]

Maximum Torque: 20 [kgm] @ 5500 [rpm]

Maximum engine speed: 8500 [rpm]

Dry weight 85 [kg] with structural aluminum billet engine block



Not satisfied with this lack of information I contacted Nembo directly. Owner Daniele Sabatini was kind enough to answer my questions and provide an updated press release that details the current state of the project. He was also kind enough to provide exclusive photos of the Nembo being track tested at the Adria circuit. I've posted a copy of the press release on the OddBike Facebook page and at the bottom of this page.Nembo is alive and well. Two 1814cc prototypes have been built, nicknamed Castor (the black carbon-fibre bike) and Pollux (the red example) after the Dioscuri twins of Greek mythology. Prototype 002, Pollux, is currently for sale at an undisclosed price - interested parties are asked to contact Sabatini directly . Once Pollux is sold, limited production of the Super 32 will begin on a made-to-order basis. The production version will feature the 1925cc engine and "MotoGP" levels of construction. Claimed power remains 200hp, with 145 lb/ft of torque. Sabatini notes that the two existing prototypes are well developed but that significant revisions have been made to the engine design over the years and that the forthcoming production engine will be much improved. There are also plans to develop a racing version to campaign at the Isle of Man TT.The press release describes the Nembo as "the most expensive road sport-motorcycle in the world" and Sabatini confirms that the production version is set to cost something in the region ofa pop. Exorbitant, certainly. But keep in mind that you are not paying for a machine that uses an existing engine - the Nembo motor is 100% unique and the high price is needed to offset the enormous cost of designing and building an engine in-house without the backing of a major manufacturer (or the amortization of development costs by selling thousands of units). You are buying a hand-built concept machine, not a mass-produced amalgam of off-the-shelf pieces. As the press release notes:But if the Nembo had used the same engine design in a conventional arrangement we likely wouldn't be discussing it today, and the Super 32 would have remained an obscure project built in a shed somewhere in Rome. Instead it captured the imagination of a curious public and raised the ire of many critics. The Nembo press release notes that their online publicity was entirely viral and through the coverage of various blogs and forums.The Nembo represents the sort of technological experiment that is a refreshing diversion, an exercise in pure engineering creativity driven by passion and the desire to do things differently. True innovation in motorcycle design is a rare quality, but Sabatini has created a machine that truly stands apart from convention. The result is one of the most unique and exclusive motorcycles in the world with an iconoclastic design that flips traditional design on its head.Interesting Links2013 Nembo Press Release: