With a history of designing such engines going back to the 1920s and beyond, you could be forgiven for thinking it was Ferdinand Porsche who popularised the ʻflatʼ or horizontally-opposed engine layout. But youʼd be wrong. In a fascinating look back at en
Delwyn Mallet’s fascinating history of the flat-four engine
“1950…THE FIRST TIME A FLAT-FOUR HAD COMPETED AT LE MANS…”
Hereʼs a little test of your automotive knowledge. I recently passed a pleasant and fascinating few hours driving a 1952 Lemans 24-Hours classwinning sports car aroundmy local country lanes. Designed by anaustrian professor of engineering responsible for the pre-warauto Union Grand Prix cars, it was aluminium-bodied, torsion bar suspended and powered by a flat-four engine originally froma family saloon – what was it? And no, it's not the Porsche Gmünd coupé that won its class that year – that would be too easy (although I am very willing to take it for a spin. Please contactme via this magazine), so try again.
Give up? Before you rush to Google, it was a Jowett Jupiter R1. In terms of specification, the similarities to a Porsche 356 are remarkable but the execution could not be more dissimilar. The Jowett is a skimpy open skiff of a machine, with its 1500cc water-cooled engine placed not in the tail but as far forward as possible, ahead of its radiator and jutting beyond the front wheels.
Those of you whose automotive interests encompass more than just Porsches may have guessed the answer, but few will actually be familiar with the R1 as only three were built and later scrapped by the factory when their racing was done. This survivor was rescued by an employee and reassembled – sort of – before finding its way into the hands of a friend who, over many years, restored it to its Le Mans specification.
The 1950 race was the first time that a flat-four engine had competed at Le Mans and the 1951 event was the first occasion that two flat-four petrol engines of different makes had raced against each other. The 1953 race would be the last at which rival makes of flat-fours slogged it out.
Porsche-centric souls are prone to thinking that the good professor invented the flat-four engine when his team designed the Volkswagen Beetle, but the horizontally-opposed ʻboxerʼ engine is virtually as old as the motorcar itself.
At the turn of the century, the future of the horseless carriage was still far from certain in terms of motive power. Steam, electricity and the internal combustion engine were all in contention. Ferdinand Porsche was backing electric power with his Lohner-porsche designs of 1900 to 1905 and, for those backing the internal combustion engine, its configuration was also far from settled.
Karl Benz patented the first Motorwagen in 1886, powered by a ʻflat-singleʼ – a horizontal single-cylinder engine. A decade later Benz designed the first horizontally-opposed internal combustion engine, a water-cooled twin-cylinder device patented in 1896. Benz referred to his twin as a ʻKontra-engineʼ, contra due to the fact that the opposed pistons worked in contrary motion around the common crankshaft. Advantages of the engine were its low profile and, as the cylinders were set at 180 degrees to each other, the dynamic masses were well balanced resulting in smooth running.
Such engines of various capacities were fitted to Benz autos and commercial vehicles and in 1899 the Kontra engine, with its crankshaft set longitudinally in the chassis, was powering the first purpose-built Benz racer – and, as it happened, due to the engineʼs low profile it was rear engined, positioned under the driver and passenger. In 1900 the engine gained an extra two cylinders, creating the worldʼs first flat-four. The 54440cc flatfour, still fitted over the rear wheels, powered a racing Benz – which, incidentally, was the first Benz to feature a steering wheel on an inclined column – and was also the last Benz ʻflatʼ engine.
In France, Mors was not far behind Benz in producing a flat-twin. The 850cc Mors ʻPetit Ducʼ of 1899 featured air-cooled barrels with water-cooled heads – something that Porsche didnʼt adopt until the late 1970s, once again proving that thereʼs nothing new under the sun!
The first car designed entirely in Britain, and in 1899 rather late out of the starting blocks, was the work of Frederick Lanchester and featured a remarkable horizontally-opposed 4033 cc engine in which each opposed piston carried two connecting rods coupled to two contra-rotating crankshafts, resulting in a remarkably smooth running engine. Even more extraordinary was that each cylinder was serviced by only one valve, functioning as both inlet and exhaust.
In 1901 another British company, Wilson-pilcher, offered an advanced front-engined ʻsilent and vibrationlessʼ water-cooled flat-four powered car, complemented in 1904 with a flat-six option. Just one example survives, a four cylinder.
In the USA Henry Ford was making his first tentative steps on the way to becoming an automotive giant. His one-off ʻSweepstakesʼ racer of 1901 had an opposed-twin engine with a massive 7-inch bore displacing 593 cubic inches (9.7 litres!). Fordʼs first production car, the 1903 Model A, was powered by a flat-twin of 101 cu ins (1668 cc) and the follow up models C and
F also had boxer engines but of slightly larger capacity before adopting an in-line four in 1908 for the car that made Ford a legend, the Model T.
As the 20th century got underway the front mounted, multicylinder, in-line or ʻVʼ engine soon became the norm in automobiles and the flat-four boxer went into hibernation. However, flat engines were well suited to use in aircraft and persist to this day. The first was used by Brazilian aeronautical pioneer and superstar Alberto Santos-dumont in 1909 in his ʻDemoiselleʼ series of monoplanes which were powered by both air-cooled and water-cooled twins. In time, the VW, the 356 and the 911 engine were all modified for use in aircraft.
Bradfordʼs Jowett brothers, blacksmiths and intuitive engineers, had ambitions to build a better small car engine than those then available and set up business in 1901. In 1910, after a few false starts, they launched a light car (curiously out of date as it was steered by tiller, the last to be so guided) powered by a torquey water-cooled 816cc flattwin that would stay in production until Jowett ceased car production in 1953 when it was still powering their ʻBradfordʼ vans – making it the longest production run of a British engine.
Obviously very much of the ʻif it ainʼt broke donʼt fix itʼ school, it was not until 1935 that Jowett added an extra pair of cylinders, and an extra carburettor, and increased capacity to 1166cc. The four-cylinder engine was in production until the outbreak of WWII but was not as popular with conservative Jowett customers as the venerable twin.
The flat-four may have dropped out of favour in automobiles but flat and V-twins proliferated throughout Europe before and after WWI in lightweight cycle cars and motorcycles from literally hundreds of different manufacturers, the Morgan three-wheeler, launched in 1909, being one of the longest lived. In the USA there were even flat-twin-powered washing machines for rural communities without electricity!
In Britain, ABC (All British engine Company), Rover and Aerial were notable for their flat-twin machines, but the most influential twin-cylinder design of the interwar years was the Czechoslovakian Tatra T11 introduced in 1923. This groundbreaking design was powered by an air-cooled 1105cc engine mounted on the nose of its torque-tube spine chassis. A four-cylinder version, the T30, followed in 1926, and rearengined prototypes in 1931/33, which continue to stir passions and controversy when discussing the gestation of the Beetle – but we wonʼt go there now.
Tatra launched a much more sophisticated, aerodynamic and rear-engined saloon in 1936, the T97, (a smaller version of their V8 T87) powered by an aircooled 1.8 litre flat-four engine derived from the 3litre V8. The T97 was shortlived due to the war and Czechoslovakia's annexation but Tatra introduced an updated version, the T600 or 'Tatraplan' in 1948 with a new 1952cc flat-four aircooled engine – with a cast aluminium fan housing that could be mistaken for that of a 911. Incidentally, the ʻotherʼ major Czech manufacturer, Skoda, built an advanced one-off streamlined saloon in 1935, with a flat-four engine mounted ahead of the rear transaxle.
Although little known in Britain, the influence of the Tatra T11 and four-cylinder T30 should not be underestimated. Hans Ledwinka, the highly respected chief designer of Tatra, was a contemporary of Porsche and much admired by Hitler who cited the little Tatras as inspiration for his own 'peopleʼs car'.
With the idea of a ʻVolkswagenʼ becoming an obsession in the German-speaking countries, Austrian company, Steyr, introduced their own ʻpeopleʼs carʼ in 1935, the pretty, streamlined, Type 50 ʻBabyʼ, powered by a front-mounted 984cc flat-four, water-cooled engine. 13,000 were built before WWII ended production.
“STEYR INTRODUCED THEIR OWN PEOPLE’S CAR IN 1935…”
Flat-four engines were once again gaining favour with the engineers of middle-europe, but it was by no means certain that the VW – and subsequently the first Porsches – would follow that route. For quite some time the Prof favoured a two-stroke vertical twin with double pistons in each cylinder. A flat-twin was also a front runner, as was a three-cylinder radial two-stroke (Porsche's 1931/32 Zundapp protoype had used a 5-cylinder radial) – even a diesel was tested.
It was not until late in the design evolution that the ʻnew boyʼ at Porsche, Franz Xaver Reimspiess, took another look at a four-cylinder boxer and laid out the engine that powered the Beetle and eventually the Porsche sports car to their extraordinary success. (as an aside, Reimspiess also designed the VW logo.)
During WWII Jowett, now under new management, hired Gerald Palmer, a promising young designer, gave him a clean sheet of paper and more-or-less said 'surprise us'. Palmer came up trumps, producing the fastback Javelin saloon. Launched in 1947 the Javelin, despite initial reliability problems with the engine, was a sensation, praised by the motoring press for its outstanding ride and handling, as well its looks.
Palmer chose the flat-four configuration for his engine, almost certainly in deference to Jowett's legacy in the 'flat' tradition but also due to its advantages in smoothness of operation and low centre of gravity. Despite the engine being well up in the bow and in the airstream Palmer chose to watercool the engine, again, as Jowett's twin was so cooled. (Alec Issigonis, working at Morris Motors Ltd on the soon to be launched Morris Minor, had also specified a flat-four engine but it was vetoed by the management for cost reasons.)
The merits of the Javelin were demonstrated by a sensational class win in the 1949 Spa 24-Hours race and the team prize in the Monte Carlo Rallye, which prompted Jowett to build what would become the Jupiter two-seater sports version. Gerald Palmer had left the company by this time and through a convoluted chain of connections and aspirations Jowett entered into collaboration with ERA (English Racing Automobiles) to build the proposed and as yet to be designed car, and this is where Professor Eberan von Eberhorst enters the frame.
Although Ferdinand Porscheʼs team had, in 1933, designed the V16 Auto Union Grand Prix car, it was not to be built in Stuttgart but at the Horch works, part of the Auto Union conglomerate, 400kms away in Zwickau, Saxony. Horch had to create a racing department from scratch and Professor Porsche recommended Austrian engineer Eberan von Eberhorst should be in charge. Von Eberhorst remained at Horch until the war and was responsible, after Porscheʼs contract expired, for the new 3litre formula V12 Type D of 1938.
Fleeing the Russian occupation at the end of the war, von Eberhorst arrived in Gmünd in time to try 356/01, the mid-
engined, space-framed roadster that was the first to carry the Porsche name – and he was mightily impressed that the humble Volkswagen parts could produce such a dynamic vehicle.
Porsche was also working on a Grand Prix project (in effect a 1500cc mini-auto Union) for Italian company, Cisitalia, and Ferry Porsche engaged von Eberhorst as a consultant. By 1949 the Cisitalia project had stalled and von Eberhorst was tracked down and invited to join the ERA team and design a new chassis for the upcoming Jupiter.
To accommodate the Javelin engine and torsion bar suspension, von Eberhorst created a large diameter tubular chassis not dissimilar to the Auto Unionʼs. Even before a car was completed the new Jupiter Jowett, as it was initially named, was entered in the 1950 Le Mans 24-Hours – then still by far the most important as well as the most testing race in Europe, if not the world.
The companyʼs gamble paid off when it won the up to 1500cc class. Sixty cars started, of which just 29 finished, with the Jowett classified 16th. Places 21 to 29 were all in the 750cc class, first of which was a Czech flat-twin Aero Minor followed by five flat-twin Panhards and two Renault 4CVS.
The 1950 event also featured the first mid-engined racer to compete there, a rather ungainly 5-litre M.A.P. (Manufacture dʼarmes de Paris) diesel-powered roadster. The engine was a supercharged flat-four 2-stroke with two opposed pistons sharing each of the four cylinders – it failed on lap 39.
Encouraged by their unexpected success first time out, Jowett built the skimpily-clad lightweight R1 for the ʼ51 race. It failed to finish, breaking its crank on lap 19, but another standard bodied but lightened Jupiter again won its class, touring to the finish after all of the very rapid Gordinis expired. The 1951 race was significant in that it saw the return of Germany to international racing and Porscheʼs extraordinary commitment to the 24-Hours, and a two-decade long quest for outright victory. Ominously for Jowett, the 1100cc Porsche, running in the class below, finished seven laps ahead of the Jowett and a 750cc Panhard-powered DB came home three laps ahead.
Shooting for a hat trick, three R1s were built for the 1952 race. Porsche also brought three cars to the event, two running in the 1100cc class and the third, with a new 1500c engine in the same class as Jowett. Two Jowetts failed but the third car, as all of its immediate competition fell by the wayside, again cruised to a class victory.
Porsche suffered similarly, one of the smaller capacity cars retiring after six-hours, and the 1500cc car, when it was comfortably leading its class and many laps ahead of the R1, was disqualified in the 19th hour for keeping the engine running during a refueling stop. Jowett was also outrun by an 850cc flattwin Dyna-panhard in the ʻmobile chicaneʼ class! (However, this should not detract from the fact that actually finishing the race was in itself an achievement – in 1951 32 cars failed to finish, and in 1952 41 cars failed.)
Whereas in any other race the winner is the first to cross the finish line and rewarded fittingly, at Le Mans, in a manner that only the French could concoct, by far the biggest prize money was awarded to the winner of the ʻIndex of Performance' – which meant that, for instance, in 1951 a French 614cc flat-twin Monopole which came home 23rd of 28 finishers and 73 laps behind the winning Jaguar C-type took home more in prize
money! By 1952 sanity prevailed and the prize money became the same for the overall and Index winners.
Running into financial trouble and lacking the resources to develop a new car, Jowett abandoned racing while on a high and only two years later ceased car production.
The engineers at Porsche were only too aware of the limited potential of the Vw-based engine and, having committed the company to racing as a way of gaining publicity and sales, Ferry Porsche commissioned a new engine from his team. The man tasked with the job was Ernst Furhmann. Using the experience gained working on the flat-12 Cisitalia engine, Furhmann designed a double-overhead-cam engine, using shafts and bevel gears to operate the camshafts. Requiring a watchmakerʼs precision to set up but when done properly famously reliable in use, it was destined to become one of the great race engines of all time.
Given work number 547 it would soon be known simply as the ʻCarreraʼ engine and from its first appearance in 1953 would power Porscheʼs giant-killer racers for the following decade.
The last 356 ran at Le Mans in 1957, a privately-entered Carrera Speedster, which failed to finish. The last flat-four Porsches to run in the event were a quartet of privately-entered 2-litre 904s in 1965, by which time the factory 904s were running six- and eight-cylinder engines.
Post-war austerity had prompted a European resurgence in small capacity engines. Citroen launched its own peopleʼs car, the 2CV ʻTin Snailʼ. Conceived before WWII intervened, it featured a cleverly designed but somewhat feeble 375cc aircooled flat-twin. The engine would, in various enlarged forms, power several Citroen variants through the 1950s and ʼ60s.
Pioneering French marque, Panhard, hitherto a builder of luxury cars, now threw all of its effort into lightweight aerodynamically efficient small capacity cars, at first powered by a 610cc flat-twin, later enlarged to 850cc. Glas, DAF, BMW and Steyr would also produce small flat-twin-powered cars in the 1950s.
The 1957 Steyr-puch used a Fiat 500 body supplied under licence but powered by its own flat-twin developed by Erich Ledwinka, son of the pre-war Tatra designer. Starting at 493cc and 16bhp by 1964 the engine had been enlarged to 660cc and the hot racing versions were pushing out up to 60bhp. In the hands of Polish rally ace, Sobieslaw Zasada, the potent Puch even won the 1966 Group II European Rally Championship, becoming (and remaining) the smallest capacity car to do so.
A French ʻmight-have-beenʼ luxury car of advanced design was the 1950 Hotchkiss-grégoire of which fewer than 250 were made before production ceased in 1954. The chassis and much of the running gear was composed of aluminium castings and it was powered by a 2180cc water-cooled flat-four engine driving the front wheels. Citroen intended their magnificent and revolutionary DS, introduced in 1955, to be powered by a flat-six air-cooled engine, but sadly, although prototypes were tested, it
had to make do with the existing in-line four-pot engine from the Traction Avant.
In Britain AC Cars spent more money than they could afford building, without success, prototype flat-four and flatsix engines designed by their Polish ex-aero engineer Zdzislaw Marczewiski.
Irish-born tractor mogul Harry Ferguson devoted much effort in the late 1950s developing an advanced 4-wheel drive car that featured anti-lock brakes and a belt-driven SOHC 2.2 litre flat-four engine. He died in 1960 but his company continued development and the R5 was first shown in 1965. It was not pretty but technically way ahead of its day and went much better than it looked. Subaru launched its first 4WD boxerengined car, the Leon, in 1971.
In the US Preston Tucker made a bid for automotive fame in 1948 with his Tucker 48 sedan – the 'car of the future'. Tucker's own engine ran into design problems so he bought-in a Franklin flatsix air-cooled engine most commonly used in helicopters and somewhat inexplicably then set about turning it into a water-cooled motor. Eventually only 51 Tuckers were built.
Towards the end of the 1950s American automobile manufacturers began to think small(er) to counter the European imports. The most radical amongst the ʻcompactsʼ was the 1960 Chevrolet Corvair, the nation's first and only air-cooled, rear-engined car. The sixcylinder, aluminium engine was secretly road-tested in converted Porsche 356s (see Classic Porsche #37). The first six-cylinder Porsche road car? In 1962 the 150hp Corvair Spyder turbocharged option became available.
Undoubtably prompted by the success of the Beetle, and Porsche, there was a renaissance in the flat-four configuration. Lancia introduced its aluminium 1500c water-cooled engine in the Flavia in 1960, variants of which would be produced until the mid 1980s. European Car of the Year in 1971 was the technically advanced Citroen GS, powered by an all-new 1015cc four-cylinder ohc air-cooled boxer engine.
Another exceptional boxer-powered car to hit the highway in 1971 was the Alfa Sud, designed by ex-porsche engineer, Rudolf Hruska. Born in Vienna in 1915, Hruska was yet another of Porsche's Austrian engineers, joining the consultancy in 1938 where he stayed until the end of the war. Hruska then moved to Turin where, along with Carlo Abarth and von Eberhorst, he was involved with Piero Dusioʼs Cisitalia project, liaising with Porsche, still then based in Gmünd. After Dusio pulled the plug on the Cisitalia effort, Hruska worked for Alfa Romeo, Simca and FIAT before, in 1967, being offered the chance to design Alfaʼs first fwd car. The resulting Sud featured an 1186cc OHC boxer engine (later it grew to 1490cc) that would happily spin to 7000rpm, provided revelatory handling and was one of the great cars of the ʻhot hatchʼ era.
By the late 1960s, Porsche was a flat-six company as far as its road cars were concerned but was forced by marketing circumstances to lend its name to the Vw-powered 2.0-litre 914. In 1976 Porsche introduced the 912E as an entry-level model for the American market using the same VW engine but it was short-lived and after a few months it too went out of production.
The Beetle itself refused to die, becoming a living fossil, until the final one rolled off the Mexico production line in 2003. Since then it has been left to Subaru to uphold the tradition of the four-cylinder boxer engine but in recent times Porsche returned, somewhat controversially, to the flat-four arena with the turbocharged Cayman 718. CP
“PORSCHE RETURNED TO THE FLAT-FOUR ARENA WITH THE 718…”
Opposite: Le Mans 1952 – a pair of Jowett Jupiter R1s (#46 and 64) sandwich an Osca as they chase after the Porsche 356SL of Lachaize and Martin. Both Jowetts were powered by flat-four water-cooled enginesBelow left: 1877 Benz engine from which the ‘horizontal single’ engine for the first motor car was developedBelow right: In 1896, Benz patented this water-cooled horizonatlly-opposed twin, called the ‘Kontra-engine’
Above: The 850cc Mors ‘Petit Duc’ of 1899 featured air-cooled cylinders with water-cooled heads – rather like Porsche’s race engines of the late 1970s and ’80s!
Below left: Ford’s ‘Sweepstake’ engine was a flat-twin displacing 9.7 litres!Below right: Ford’s first production engine was this 1668cc flat-twin of 1903
Above left: Bizarre in the extreme, the 4033cc Lanchester engine in which each opposed piston carried two connecting rods coupled to two contra-rotating crankshafts…Above right: In 1901, WilsonPilcher offered an advanced front-engined ‘silent and vibrationless’ water-cooled flat-four powered car. This was joined in 1904 by a similar flat-six (see bottom right photograph)
Below left: 1952cc flat-four engine used in the 1949 Tatraplan saloon. Cooling system is remarkably similar to that of the 911!Below right: Steyr used this water-cooled 984cc flat-four in its own version of the people’s car in 1935
Above left: Pre-war Jowett was powered by a flat-four, displacing 1166cc. Oddly, it did not prove as popular as the older 816cc flat-twin, which remained in production until 1953!Above right: The post-war version of the Jowett ‘four’ as used in the Javelin
Above left: AC Cars also got in on the act, spending money they could ill afford on developing a watercooled flat-six engineAbove right: French twincylinder Mathis VL333 featured water-cooling, with individual radiators for each barrel and head
Below left: The V1 prototype that ultimately led to the VW Beetle was powered by a flat-twin air-cooled engineBelow right: A complete contrast in every respect, Citroen’s flat-four watercooled GS engine of 1971 featured overhead camshafts
Below: One of the finest, most free-revving flat fours of modern times was the 1186cc Alfa Sud engine (it later grew in size to 1490cc). It was designed by Rudolf Hruska, an ex-porsche engineer who had worked on the post-war Cisitalia project, among others