HANS MEZGER
We look back at the life of the man behind the 911 and 917 engines…
For enthusiasts the most revered figure at Porsche after Ferry himself, Hans Mezger gave his name to the flat-six and was at the heart of the company’s motor sport triumphs for almost three decades. The racing car most associated with Porsche is of course the legendary 917, today celebrating its 50th birthday: this was Hans Mezger’s greatest achievement
Abright schoolboy with a penchant for maths and physics, after his Abitur (bac) he had to work for two years in a foundry before a place was available at his local university, Stuttgart. There his ambition was to study aviation, but of course in the Germany of the early 1950s this was not possible and the young Hans trained to be a mechanical engineer with a view to working in the automotive industry.
This was the time of the Wirtschaftswunder, the economic miracle, and mechanical engineers were in demand: Mezger says Opel in Cologne was interested in him and Timken Bearings offered to train him in the US. However, although it was a small company and he had seen no vacant positions, he had become aware of a sports car maker near his home by the name of Porsche: as he told Peter Morgan in 2010:
‘When I was taking driving lessons, I used to drive past Werk 1 and I liked the look of the 356 and they were driven so fast that my driving instructor said Porsche drivers did not know how to go slowly! So as soon as I graduated from university I wrote speculatively to Porsche: after a couple of weeks I got a positive reply and I started there in October 1956.’
Mezger began in the Calculations department under Egon Forstner where his early tasks involved stress calculations on valve gear components, springs and rocker arms. This suited him because he was soon involved with development of the four-cam ‘Fuhrmann’ engine, then proving difficult to tune because of valve gear wear: the master camshaft for the four-cam was machined by Schleicher in Munich, an expensive process made more so because for each batch of engines Porsche had to supply fresh cam profile data.
Mezger’s intuitive understanding of the complexities of camshaft rotation geometry meant Forstner entrusted him to construct a mathematical formula so that Schleicher could standardise its machine settings. Within a few years, these
calculations, which took Mezger weeks to complete, would be carried out by computer.
‘The formula was very helpful,’ he recalls. ‘We used it (for the camshaft profiles) on the 804 F1 car, on the 904 and on the eight-cylinder 2.0- and 2.2-litre racers until 1968. It is also the basis of the air-cooled 911 engine.’
Mezger appreciated the way senior people like technical directors Klaus von Rucker or Ferry Porsche himself would spend time in the workshops of Werk 1, and he felt very much at home at Porsche. He was especially impressed by Ferry Porsche: ‘I found him a quiet fellow, but it was always very good if you could talk to him: he knew better than anybody what had to be done to make competitive, reliable sportscars and he had a way of getting his staff to follow him. He was an example to everybody.’
By 1960, Mezger was already a central figure in engine development at Porsche. His natural curiosity led him to think laterally – looking, for example, at an MV Agusta racing motorcycle because this had the highest power/litre of any engine and exploring such areas as velocity of exhaust gases, the angle of valves and the shape of combustion chambers. This would be vital in the development of the 901 flatsix and this became urgent in 1963 when the initial six-cylinder design for the forthcoming new model struggled to produce 110bhp when 130bhp was required.
Until then, Mezger’s main task had been the grand prix car, but abruptly at the beginning of February 1963, he and others were instructed to cease all work of the eight-cylinder racing engine (which had taken Gurney to two wins and fifth place in the world championship). They were to work on the 901. Mezger told Peter Morgan:
‘It was my responsibility to redesign the 901 engine. I did the general layout, the seven-bearing crankshaft, the combustion chambers with larger valves and (unlike the 356) a dry-sump oil system. We wanted a car that would be good
“AS SOON AS I GRADUATED, I WROTE TO PORSCHE…”
for road and competition.’
He says a group of six or so engineers was involved, including new Zuffenhausen recruit Ferdinand Piëch: ‘He could open doors to make things happen. He was a visionary and he had many good ideas.’ He says it was Piëch who wanted the basic design to allow scope for expansion (in ten years the 1991cc would reach 2993cc), and a design life of at least eight years was envisaged. The unit also had to be reliable. Mezger described how they used chains to drive the camshafts rather than the complex, bevelled gear camshaft drive of the four-cam.
‘It was much simpler and less expensive and it took less time to build them. Later I would carry the chain drive over to the 917.’
The 911 launched, Mezger’s efforts turned towards competition engines and hill climbing. That was Porsche’s speciality and it allowed Porsche to experiment: ‘We tried out ideas such as pressurised fuel tanks and beryllium disc brakes that we couldn’t test on endurance cars.’ With its simple rules – two litres maximum capacity and absence of minimum weight limit, the Bergmeisterschaft was made for the light, agile Porsches and it particularly appealed to Piëch: in 1965 he became technical director, bringing immense energy to the racing department.
Seven racing cars, starting with the 906 and culminating in the 917, would emerge under Piëch’s leadership in the next five years. Says Mezger: ‘Piëch was much more driven and ambitious than Ferry, he worked long hours and never relaxed, but it was always Ferry who had the best ideas about how the Porsche road car had to be.’
Mezger had been at Zuffenhausen only four years when he acquired his first Porsche, a nine-year-old Pre-a. Later he bought Piëch’s former 901, chassis No.06. ‘I recall it was suddenly terrible to drive through Munich traffic (on the way back from Austria). Below 2500 rpm it was horribly noisy. (It was the chain tensioner failing because it had run out of lubricant.) We had been so busy in the early years that we never found a solution. All the Reparaturwerkstatt could do was to replace the tensioner, so in 1968 I was asked to investigate.
‘I devised a repair to seal the oil in the tensioner and we thought we would make about 100 pieces to repair customer cars. This worked well, in fact it lasted about 25,000km, but somehow it went into production which we never intended! It was not until the 3.2 Carrera (and the intervention of Peter Schutz) that Zuffenhausen started lubricating the cam chain tensioner from the engine oil supply.”
As the 2.0-litre 906 evolved into the 2.2-litre 907, Piëch made known his ambition to win the 1968 Manufacturers’
“PIËCH WAS MUCH MORE DRIVEN AND AMBITIOUS THAN FERRY…”
World Championship and a flying start was made at Daytona when 907s took the first three places. Later the 3.0-litre engine was ready. Mezger says:
‘We did make two experimental eight-cylinder engines with four valves per cylinder, one air-cooled and the other water-cooled. We quickly found air cooling with four valves was not possible – the upper pair of valves stops the cooling air reaching the lower pair. But we abandoned further investigation of this in June 1968 to concentrate on a 12cylinder motor which gave far more power than an eight.’
This of course was the motive power of the 917, a racing car developed at incredible speed to the point where Porsche could present 25 ‘finished’ cars for FIA inspection in March 1969 and therefore be eligible for Le Mans, the winning of which was Piëch’s ultimate goal (see Return of the King, page 8). Mezger reflects that it was an immense task to configure and build the cars in such a short time:
‘To be asked to build 25 cars just for homologation like that surprised us. Nobody else had been asked to do it and nobody was ever asked to do it again. We were also surprised that Ferrari, too, was not asked to do this as well.”
Mezger’s design for the 4.5-litre engine was based almost entirely on his experience building the 901 and subsequent racing engines. As he told Peter Morgan, ‘The chassis and engine were an evolution of what we had been doing before: what we learned on the six-cylinder engine we used on the eight-cylinder and again on the twelve (of the 917). This used the same head and valve angles because there was no time to do anything else, and in any case it would probably produce enough power to win Le Mans.’
As well as power, reliability would be crucial and one of his first moves was to design a crankshaft which transmitted its power through a drive from its centre rather than at the end: he knew from experience of the eight-cylinder engines that crankshaft vibration on such a long engine would otherwise cause it to fail. At Le Mans only ten weeks after that presentation to the FIA, the works 917 driven by Attwood and Elford was leading until the 23rd hour when the gearbox bell housing cracked and the clutch failed. They had simply not had time to test it properly, says Mezger.
The following year the now 5.0-litre 917 was unstoppable and when in 1971 it proved so again, the FIA intervened with the 3.0-litre rule to ban it. It was a frustration for Porsche, but Hans Mezger’s reputation was made: he wrote a paper for engineering associations and the Institute of Mechanical Engineers was one of several professional groups to honour him. Indeed, even after his retirement in 1993, he remained a popular speaker and addressed among others the Société Ingénieur Automobile in Lille.
But in 1972, Mezger was only 41: there was still plenty to do: excluded from Europe, Porsche looked to the American Can-am series. Here huge engines and 6–700 horsepower were the norm. Piëch had already asked Mezger to investigate a larger 917 engine, but expanding it to 16 cylinders still did not match the power of the fastest Can-am cars and the extra weight made the 917 more difficult in corners. So Porsche turned to turbocharging. The great challenge was controlling the turbo boost: the sudden surge of power when the turbochargers took effect could throw the car off its trajectory (see Giving it Boost, starting page 72).
This problem was eventually resolved by his colleagues, Valentin Schäffer and Helmut Flegl, but Mezger himself worked to modify cylinder heads which became much hotter on turbo engines with additional oil flow. He also designed a water-cooled, 4.2-litre, 12-cylinder naturally-aspirated ‘Indianapolis’ engine, ‘but we abandoned that project. There was no justification when turbocharging was working so well for us in the Can-am.’ Porsche would win this championship in both 1972 and ’73.
The oil crisis caused a refocus. Porsche abandoned top level sports car racing competition, which was also very expensive, and concentrated on making a production turbo 911 as a basis for GT racing. From this came the 934 and 935 series of turbocharged 911s which would dominate Groups 4 and 5, and the 936, its chassis based on the Canam 917. This model won at Le Mans in 1977 and 1981, and was the basis for the immensely successful 956/962 sports racers which dominated the 1980s.
In his descriptions of the 1950s and ’60s, Mezger talks mostly in the first person, but by the mid-1970s, ‘I’ has become ‘we’ and clearly his role had become more that of the director than engineer. He nevertheless remained intensely involved: Porsche’s mastery of turbocharging attracted a lot of attention, not the least of which came from
Formula 1, especially when Renault entered grand prix racing in 1977 with a turbo car.
When Ron Dennis of Mclaren approached Porsche with a view to buying a turbo F1 engine, once agreements had been reached, it was Mezger who managed the relationship. He says despite what he had heard about Dennis, he found it easy to get on with the Briton. The impression was evidently mutual for subsequently Dennis has said ‘I had complete faith in Hans Mezger and his technicians because he was such an assured, natural engineer.’
Successful though the relationship was – Mclaren won three championships – Mezger believes that ‘although we were paid for this, I don’t think Porsche earned a lot of money from the project.’ He describes a relationship which rather faded away in the end:
‘In Porsche things were beginning to change…and it was a disappointment when Dennis decided to change direction (for 1988 Mclaren turned to Honda), and I had to reassign the people I had working on the Mclaren engine.’ Nevertheless Porsche did again enter the F1 hothouse, building a naturally-aspirated V12. Mezger describes this venture as a ‘step too far: I don’t believe we even had a customer for it.’ Eventally Jackie Oliver’s Arrows team took the V12, but Mezger says he never achieved the rapport with the Arrows people he had had with Mclaren; then Porsche closed the project down before the V12 was properly developed.
This was a very controversial decision (PR director Manfred Jantke resigned in protest), but given Porsche’s difficult financial position in 1991, Mezger, who was becoming disillusioned at Porsche, could understand the logic. His long time colleagues Helmuth Bott, Peter Falk and Valentin Schäffer with whom he had worked since the 1950s had all left. However, when in 1992 the newly appointed Wiedeking announced to senior managers a new water-cooled engine and two new cars, the Boxster and the 911, ‘I decided to stay on to look after the young engineers promoted for this project before I retired.’
Mezger’s farewell party in 1993 was probably the last occasion which brought together the surviving members of the team which built the 911 and the 917: although Hans Mezger worked tirelessly for Porsche for another two decades, these cars, and especially their flat-six and twelve cylinder engines, are his great legacy.