1991 Mercedes-Benz Sauber C291

In 1991 Mercedes-Benz Sauber launched a new car named C291. The new car competed alongside C11.

This year season, would be different though, because FIA president Max Mosley was driving forward a change in regulations, making 3.5 litre naturally aspirated cars the premier contenders. These would weigh no more than 750 kilogrammes and it was expected that their engines, similar to those in Formula One, would develop more than 600 horsepower. His plan, and Bernie Ecclestone’s, was to take all the manufacturers involved in Group C up the garden path, which led to Grand Prix racing.

The old Group C cars were given a year of grace, to fill the grids, but the minimum weights were increased to 1,000 kg, except in the case of the Porsche 962Cs which could run at 950 kg, and the triple rotary engined Mazda 787s which could race at 830 kg. Race distances were reduced from 480 kilometres to 430 kms, and the first 10 places on the grids were reserved for 3.5 litre machines, irrespective of their qualifying times.

 

Mercedes, having made a long-term commitment to endurance racing, would not be left behind by Peugeot, Jaguar, Porsche and Toyota. Design of the C291 was started in 1989, first in Stuttgart-Ünterturckheim where race engine director Dr Hermann Hiereth laid out an unusual flat 12-cylinder engine, M291. It was not a ‘boxer’ in that the opposing cylinders were aligned, with two main bearings on each journal of the crankshaft. Drive to the gearbox was taken from the central point of the crankshaft, to reduce torsional vibrations, and the six-speed gearbox was transverse to the block, and higher up, to make more space for the underfloor venturi. The lowest possible centre of gravity was a fundament of the design. TAG Electronics, a McLaren subsidiary, supplied the engine management system and for the first time it made telemetry available, conveying engine data to five monitors in the pit garage.

In Hinwil, designer Leo Ress was not a happy man. He had not been present at the crucial meeting in Stuttgart when the design of the flat-12 was agreed, and he would have opposed it strongly on the grounds that he would not have enough floor area to have the venturi he thought necessary. But, like the Porsche 962C’s flat engine, the Mercedes was inclined upwards towards the rear, and Ress had to do his best with the tool he was given.

Like the C11, the C291 had a full carbon fibre reinforced plastic monoque, even stronger in that it incorporated the roof and roll-over bar. Even so, the target weight of 750 kg was not met, initially, as the new car weighed 790 kg at the outset. Winter testing did not go well, as the Sauber Mercedes team had to deal with a number of new car problems, among them with the push-pull gearshift operation which replaced the traditional H-gate. The C291 was entirely new, of course, “only the wheel bearings have been taken from the C11” said Dr Hiereth, and problems were anticipated. In particular the TAGtronic system with 24 ignition coils was a nightmare, its enormous telemetric data bases causing continuing problems at the tracks.

As the season approached, Mercedes’ motorsports director Jochen Neerpasch had to make a difficult decision. Jean-Louis Schlesser and Jochen Mass would run the C11 in the early part of the season, up to and including Le Mans (which would return to the World Championship), while two ‘rookies’, Karl Wendlinger and Michael Schumacher, would handle the C291 from the outset, at Suzuka in April. The two youngsters had been given baptism races in the C11 in 1990 and now, at the age of 22, they would embark on a full World Championship program. Both had won the German Formula 3 championship, Wendlinger, the Austrian, in 1989 and Schumacher, the German from Kerpen, in 1990.

“To be honest we just ran out of time with the new car” admitted Neerpasch in the run-up to Suzuka. “The C291 is a very good car, with very good potential, but we don’t have it totally under control. If it was reliable now it would easily beat the C11. As it is, although we think more of the C291, we are playing a little bit safe at Suzuka.” (And at Monza and Silverstone, he might have added).

It was a good call. Derek Warwick opened a lead of 30 seconds in the opening stint, at the wheel of the Silk Cut Jaguar XJR-14, while Keke Rosberg in the Peugeot 905 defended second position from Wendlinger. So far, so good, but at the pit stop the Jaguar’s starter motor failed, and Schumacher left the Mercedes pit leaving a vapour trail as the fuel filler had jammed partially open, quickly causing a fire. He had to bale out, leaving Mauro Baldi and Philippe Alliot to win for Peugeot, a lap ahead of Schlesser and Mass in the Mercedes C11. “We were surprised at how competitive the C11 was” said Neerpasch.

Monza was, for me, an eye-opener. I walked through the tunnel at the top of the pit-lane during practice, to observe the first chicane from the outside. It was different 20 years ago, cars coming off the Parabolica and past the pits at full speed, then braking heavily for a left-right ‘bus stop. The silver C291 made me catch my breath as Schumacher appeared to miss his braking point for the chicane, by 20 or 30 metres, and it seemed that he would arrive at the Lesmos with no wheels on his car! No, he got away with that, on that lap and several more after that. I was so excited by this that I told Dr Hiereth and Leo Ress that they had  to go out there and see what young Schumacher was doing with their car. They didn’t, but they did go out to the complex at Silverstone a fortnight later, to form their own impressions.

Schumacher’s race was impressive, too, for as long as it lasted. The C291’s engine failed to fire up on the dummy grid, and the car was pushed to the pit-lane where it started exactly a lap behind the others. “Its progress in the first hour was extremely encouraging as Schumacher kept up with the leaders, easily it seemed, and outpaced the Peugeots of Rosberg and Baldi” I wrote for Motoring News. This was a Jaguar 1-2, with the Schlesser/Baldi C11 finishing third, and taking the lead in the World Championship. Ah, not quite what the FIA had in mind.

But under the direction of Dr Hiereth the C291’s injection system was improved with 12 butterfly flaps instead of four, raising the power to 640 horsepower at 13,200 rpm. Power losses were reduced, the water and oil pumps were changed and weight was saved in the engine, gearbox and chassis. Now, at 750 kg, the Mercedes C291 was a properly competitive car, on paper, at any rate.

Its reliability went downhill, though. Maybe weight saving had been taken too far as incorrect machining of a new batch of engine blocks led to porosity problems, and the cylinder walls were so thin as to cause a string of failures, often during the early laps of practice. Mercedes’ star was definitely waning. Having outlined the improvements, Dr Hiereth was obliged to explain the problems in the wake of a double retirement at the Nürburgring, not the place they really wanted to display their weaknesses.

The C291 frustrated the Sauber Mercedes team. The two 12-cylinder cars were on the pace of the Jaguars and the Peugeot 905 ‘bis’ at the Nürburgring, but Schlesser’s retired with a gearbox problem caused, apparently, by gear ratios being too short, while Schumacher’s stopped early with a failed engine.

“We are short of parts for many reasons” said the likeable doctor. “We could do more, if we had enough parts, and we would be more reliable on the track, too, no discussion about that. There were some steps we’d like to do, but the problems with the supply situation are very tough. We can’t go as fast forward as we want to.”

A new star was born, and it wasn’t a Mercedes. Jochen Neerpasch, the man who mentored Jochen Mass as a 22-year-old, was now promoting the remarkable abilities of Michael Schumacher. Bertrand Gachot was imprisoned in London for spraying a cab driver with CS gas, apparently after a minor traffic accident, and an opening presented itself in Eddie Jordan’s Formula 1 car, the Jordan 191, at the Belgian Grand Prix. Other team managers reckoned the Irishman was taking a big risk, but not Tom Walkinshaw, who’d noted Schumacher for some while.

Although the Francorchamps circuit is nearest to Schumacher’s home town, just over the border, he had never raced there. At first he ‘nearly’ braked for Eau Rouge, then he took it in fifth, then flat-out in sixth. Soon he was up there with the best, eventually qualifying eighth after being baulked by Alain Prost, of all people. Schumacher’s race was over almost before it began, with a mechanical failure on the rise to Raidillon, but he had already made up two places and created an impression of skills that would be polished in years to come. Oh yes, a star had indeed been born.

At Magny-Cours, Schumacher was third quickest overall in qualifying, but in the training car as both race cars were sidelined by engine failures, repeated in the race. By now, Mercedes were assembling engines in the paddock, cannibalising broken motors to make something that would hold together for a while. Schlesser’s Mercedes retired with a broken lever on the throttle valve assembly, Schumacher’s with a loose clamp in the engine cooling system.

Matters improved at Mexico City, the penultimate race of the season. Schumacher claimed a place on the front row of the grid, alongside Alliot’s Peugeot, and he then set a new sportscar lap record. The engines were holding together, too, and at the 60-lap mark, out of 98, the Mercedes were third and fifth overall, but then Schumacher’s went out with failed oil pressure and Schlesser’s with rainwater flooding the electrical system.

Finally, we visited the fabulous Autopolis circuit in Japan, the creation of an industrialist named Tomonori Tsuramaki. It was built around the perimeter of an extinct volcano, many miles from the nearest towns and served by just one road to the summit. It looked for all the world like a set from a James Bond movie, but sadly it was a work of fiction on the part of Tomonori-san, who amassed a mountain of debt. We didn’t know that at the time, but our Japanese hosts feared for the circuit’s future. Teo Fabi, about to be crowned the world champion in his Silk Cut Jaguar, declared it to be “the best circuit in the world”

The Sauber Mercedes team did not start well. Engine failures were suffered on Friday and Saturday, and again on Schlesser’s C291 in the Sunday morning warm-up. Thankfully, though, Schumacher and Wendlinger had no problems at all on race day. It seemed that a good fairy had waved her magic wand over the number 2 Mercedes as Schumacher drove an aggressive stint, passing both Jaguars and assuming the lead when Yannick Dalmas’ Peugeot went out with a blown engine.

Both Warwick and David Brabham, partnering Fabi, played a waiting game. Of course, the Mercedes would break down, it was a question of when. But it did not. The German and the Austrian drove to an impeccable victory, half a minute ahead of Warwick, another solo drive, and Fabi with Brabham. The Germans, Swiss and Austrians celebrated as only they knew how, and for a while Dr Hiereth was too overcome with tears to speak.

At long last, the Mercedes C291 had come good, Schlesser and Mass finishing safely in fifth place, and in all honesty the whole team believed in the future. Its successor, the C292, was nearing completion and would soon be undergoing tests, the designers having dealt with all the issues. The Mark 2 model would be a winner, better than the Jaguar, the Peugeot and the new Toyota, they were certain.

Source: http://www2.dailysportscar.com/?p=486    by Michael Cotton