Interview

A return to Formula 1 for Porsche's Hans Mezger

In the 15 years that the Ford Cosworth DFV V8 reigned, almost supreme, in Grand Prix racing only Ferrari provided unbroken opposition. Renault broke the mould with their 1.5-litre turbocharged engine which made its debut at the British Grand Prix in 1977, at first a no-hope laughing stock but taken increasingly seriously as it became faster, then more reliable. Today, the DFV is finished as a serious contender and Grand Prix racing has become much more international as a result with the French, Italian and German makes in the ascendancy.

For 53-year-old Hans Mezger, a presence in Formula 1 is a return to old haunts; 24 years ago he was heavily involved in Porsche's flat-8 Grand Prix engine that won a single World Championship event, at Rouen in 1962, but marked the end of the German company's interest in Grand Prix racing. For the past two decades Porsche has concentrated on endurance racing, an easier class to dominate say critics, taking the view that drivers get too much publicity in Formula 1 and manufacturers not enough. But Porsche is also a consultancy, which in its early days designed the Auto Union Grand Prix car, and it would never have refused to design an engine, or a complete car, for a customer. That opportunity came along in August 1981 when Ron Dennis, a director of McLaren Racing International, approached the German company to design a Grand Prix engine which would replace the DFV in his John Barnard designed cars. The contract was signed two months later on October 12th, and design work was handed over to Hans Mezger, deputy head of engine research and development, who has been responsible for all Porsche's racing engines since 1964.

Mezger denies that he had any preconceived ideas about the configuration Of the engine. "We always took an interest in Formula 1, of course," he says, "but without a client there were no plans on Paper. We asked for four months to study our design, and went to some races to study the targets and the problems."

The first decision was that the engine should have six cylinders in a vee formation, and detailed studies decided Mezger that the crankcase should be at an 80-degree angle (at the same time Honda came to the same conclusion) taking vibration, compactness and suitability for ground effects into consideration.

By the Spring of 1982 all the studies were complete and detailed drawings were started, taking tangible shape so rapidly that the first unit was built and running on the dynamometer by October, 12 months almost to the day since Ron Dennis had signed the contract. Without delving too deep into the politics, Dennis had committed the McLaren team to the contract without having an equally conunitted sponsor, but some involved negotiations with Mansour Ojjeh, director of Techniques d'Avant Garde, brought the Saudi company into the equation during 1982, Ojjeh and Dennis becoming directors of a new company named TAG Turbo Engines, the agreement including use of the name on the rocker covers of the Grand Prix power units.

The first time the engine ran in October last year it was powered by a motorised dynamo, lacking the all-important Bosch engine management system. Designing the hardware is comparatively easy, but adapting the electronic engine management system of injection and ignition is a specialist undertaking, in this case using an independent system on each bank of three cylinders with a central control unit. Fortunately Porsche and Bosch had some research experience with the similar system on the flat-6 956 endurance racing engines which, so equipped, appeared for the first time in April, a month after the Porsche designed TAG Turbo engine was shown for the first time in public at Geneva.

Having run for the first time under its own power in December last year, the Formula 1 engine began its road trials installed in a 956 endurance racing test car just to get some miles behind it, until the McLaren MP4 / 1D interim chassis was ready to accept the V6.

Although Mezger is reluctant to discuss power outputs, it is known that his design develops in the region of 700 bhp for qualifying and some 620 bhp for the races, on lower boost. The debut of the McLaren MP4/2 could have been in Austria in August, but was delayed until the Dutch Grand Prix at the end of that month so as to appear for the first time on neutral ground (everyone fearing what the Austrian Press would have said if the new engine let Niki Lauda down in his "home" Grand Prix!). "Our targets were not fixed exactly," says Mezger. "We decided to use the races this year to develop the engine, and to make steps from race to race. After all, the requirements for Zandvoort or Monza are different from those for Brands Hatch. Our real target was to make a simple engine, which is efficient and has good fuel economy."

So how have the first race experiences measured up against expectations? "We certainly did not expect to win our first race" says Mezger. "If we had spent three years on development, maybe, but not in this short time. We knew we had good power and reliability, but we knew we had a lot of work to do with throttle responses, and it is getting better. You can do half your development programme on the dyne, but the other half can only be on the track so that all the parts can be involved: the engine, the driver, the car and the team. For each circuit we have to decide what boost to use, we even change the size of the turbochargers, and all this is gaining us experience that you cannot gain any other way.

"The racing is very competitive, very nice, it is not a bit like Group C, where Porsche would really like to have some more competition."

Next year the Formula 1 regulations change, limiting the amount of fuel to 220 litres (12 % less) and banning fuel stops, so how will that affect the competitiveness of the TAG Porsche engine? "We have always had that in mind, and it won't be any problem," is Mezger's opinion. "We are always looking for the optimum between power and fuel consumption, and we have an efficient engine so we expect to be competitive from the start.

"In my opinion the problem is that unless we can find a regulation that covers the situation we will need two different engines, one for qualifying and one for racing. There is no fuel restriction for qualifying, of course, and none of the manufacturers are happy about the situation." So, could not Ferrari, Renault, BMW and Porsche have a gentleman's agreement not to develop qualifying engines? "We could, I suppose, but then another constructor, a new one perhaps, could come along with two or three bar boost and qualify faster. No, we do need a regulation and we are talking about this, but it won't be easy to frame it." This sounds very true, when you consider that Goodyear, Michelin and Pirelli are unable to reach agreement to ban qualifying tyres, though it is very much in their own interests to do so.

By consent one of the smallest, lightest (at 150 kg complete) and neatest power units in Formula 1, the TAG Porsche has a bore of 82 mm and a stroke of 47.3 mm to give a capacity of 1,499 cc. The beautifully cast crankcase is made from a composite of aluminium and magnesium alloy, with the twin water pumps and oil pumps placed at the front of the engine driven by the valve train gears. As you'd expect of a Porsche design, KKK turbochargers are specified, well outboard at the flanks of the car.

Mezger the designer

Hans Mezger graduated from the Stuttgart Technical University in 1956 with a Diploma of Engineering degree, and went straight to work at Porsche's Works 1 development department where his first project was to work on the valve train of the complex Fuhrmann-designed Carrera engine, its 4-cam layout leading to problems with the valve springs. In 1959 he transferred to the design department when work started on the type 804 flat-8 Formula 1 engine, remaining with the project until it was cancelled in 1962 after Dan Gurney had won the French Grand Prix. During development the car, though advanced, had two main problems, one of which was severe vibrations through the steering under braking, cured by fitting radius arms to spread the torque loads through the chassis. The second, and more serious problem was to extract enough power from the air cooled engine, the combustion chamber shape not being very good. With new combustion chamber design the power did go up from 160 bhp to around 180 bhp, but it was still not enough to cope with the Coventry-Climax and Ferrari rivals so Dr Porsche stopped the F1 programme to concentrate on sports car racing, where the four-cam type 804 engine, in 2-litre form, met with considerable success.

Through the 19696 Hans Mezger was involved in many production and race engine projects, from developing the 911S unit through to the flat-8 908, which was in effect a four-cam "six" with two more cylinders added to bring in up to 3-litre capacity. His first assignment to design a complete racing car was project 917, the space-frame flat-12 car which won two world endurance racing championships, and then in turbocharged form two Can-Am titles. Though Mercedes had preceded Porsche in taking the drive from the centre of the crankshaft, Mezger came to his own conclusion that this was the logical layout considering that this was, after all, the mating of two six-cylinder engines, and crankshaft stiffness (and previous problems with flywheel mating) dictated an unusual solution.

The first 917 engine gave 540 bhp from a 4.5-litre capacity, but in 5-litre form for 1971 it gave 600 bhp, while an experimental 16-cylinder engine produced in excess of 750 bhp. Even that was overshadowed by the turbocharged engines developed for Can-Am racing, the final 5.4-litre version for 1973 developing no less than 1,100 bhp making it the most powerful engine ever produced for road racing.

"It was quite a big decision to turbocharge that engine", Mezger explains. "Some of the Indy engines were turbocharged, but there the throttle lag did not matter too much. General Motors, and BMW, had produced turbocharged cars but they dropped their Protects because of throttle lag, so we thought we were trying something quite new. We did a lot of work with boost control, via a wastegate so as to by-pass the turbine when the pressure built up too much, and to keep the turbine spinning. The funny thing is we thought we had invented the waste-gate, but when we went to patent it we found that Garrett had already done so, using a butterfly valve... though that tended to stick when it got too hot."

Throttle lag was brought under control to the extent that the Can-Am cars were very manageable, for expert amateurs as well as professional drivers. Once the SCCA decided on a change of rules late in '73 for the following year, Dr Ernst Fuhrmann, by than chief executive of Porsche, set in motion the development of the 911 Carrera Turbo which was raced by the company in 1974 in readiness for the new Appendix j "silhouette" formula which commenced in 1976. Again, Mezger and his deputy, Valentine Schaeffer, did the development work for the Carrera Turbo, the roadgoing 911 Turbo, and the 934, 935 and 936 models which followed.

In fact since the Can-Am development ceased ten years ago all programmes have concentrated on the production flat-6 block, which has given as much as 750 bhp in turbocharged form for the 935. Mezger always knew that air cooling was a major constraint, the valves needing to be so big that normally only two could be used per cylinder, no a significant advance was made late in '77 when the water-cooled head system was developed, this allowing the use of four valves per cylinder. As far back as 1969 two four-valve versions of the 908 engine were produced, one with air cooling and another with water, giving 390 bhp at an early stage compared with 370 for a good two-valve unit. Like the flat-16, though, these projects were carried out in case they were needed, but were never proceeded with.

The Group 6 type 936 equipped with four-valve heads for 1978 developed 620 bhp, with a capacity of 2,142 cc, against 580 bhp for the two-valve version. The 3.2-litre 935 / 78 gave 750 bhp and won its debut race at Silverstone comfortably, but after a fraught race at Le Mans it was not raced again, lest the company become too dominant over its customers. A water-cooled 1.4-litre "baby" Porsche was also developed, but was not raced.

Indianapolis was a big disappointment to Porsche, for having resolved to return to single-seaters with the Interscope team, Mezger and his staff designed a 2.65-litre, 630 bhp version of the flat-6 with welded cylinder heads, and no cooling fan since methanol fuel allowed the unit to run cool enough. An assumption was made, backed by a verbal agreement with USAC, that the unit would run on 54 inches of mercury boost, midway between the specified 60 inches for a 4-cylinder engine and 48 inches for an 8-cylinder engine. "We had problems during testing with con-rod lubrication, as the 911 crankcase with its standard oil feed was not designed for continuous operation at 9,000 to 10,000 rpm. We got that under control, but then USAC told us that we would have to run with 48 inches of boost like an 8-cylinder. To have obtained the power, we would need to run at still higher revs, and we knew that was not possible, so the project had to be cancelled."

Bad news for the Indy programme, but good news for the endurance programme since the engine configuration, with some essential modifications (such as fitting a cooling fan!) was used for the 936/81 which won Le Mans, and then in the 956 which has dominated the French classic in the past two years.

Porsche's engine research and development department, headed by Paul Hensler, employs up to 140 people working not only on in-house developments, but on customer contracts as well. As his deputy, Mezger also has special responsibility for a team of 20 who, during 1983, have worked on the TAG Formula 1 engine contract, the Group C 956 engine development, an evolution for SCCA racing, the Group B prototype which made its debut at Frankfurt, a Group B car evolution, plus another outside contract, which makes quite a variety.

Mezger is quite undeterred by the teething problems encountered in the early races, his engine having just dropped a valve in Lauda's car during practice for the European Grand Prix. "If there is a consistent problem, we have the resources to correct it," he explains very simply. It has taken Porsche a long time to return to the hot-bed of Formula 1, to an environment of intense competition, and it will be interesting to see how the engine shapes up in 1984. — M.L.C.