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Le Mans History, To Be The Fastest

The WM P88 was built for one thing; speed

Earlier this year the French automotive industry lost one of its most respected designers, and Le Mans laid to rest a man who had, for more than thirty years been amongst it’s most enthusiastic and determined supporters; Gérard Welter

For 47 years Welter had been responsible for some of Peugeot’s most familiar road car designs, including the iconic 205, one of the most successful small hatchbacks of the late 20th century, and the car widely considered to have saved Peugeot at a time when the manufacturer faced an uncertain future. Others in his stable included the 304, 405, 406 and 604, through to his final contribution; the stylish Peugeot RCZ Coupé that was in production until 2015. Between 1979 and 2010, however, he’d been better known to Le Mans racegoers for a succession of prototypes that competed in the 24 Hours, often blisteringly quick, but with very varied degrees of success.

The WR LMP04-Peugeot from 2006 is pictured above.

Welter passed away on 31st January this year, and in tribute, and to mark the thirtieth anniversary of one of his most extraordinary achievements, we are enormously grateful to Alan Lis for permission to reproduce his article (first published in Racecar Engineering) on the WM P88. This was the Welter prototype that established an outright speed record for the 24 Hours that is unlikely ever to be bettered.

At the 1988 Le Mans 24 Hours a French garage owner driving a car built in a workshop at the bottom of its creator’s garden and run by a team with no full time members set a record that is likely stand for all time.

Shortly after 8.46pm on the evening of Saturday 11 June Roger Dorchy driving a WM P88 chassis powered by twin–turbocharged Peugeot PRV V6 engine rocketed through the radar speed trap on the Linge Droit des Hunaudières (the Mulsanne Straight to English speakers) at 407kph (253mph) – the first time (officially) that the 250mph barrier had been broken on that famous three and a half mile stretch of Route Nationale 138 (nowadays D338).

Peugeot employees Gerard Welter and Michel Meunier had formed WM in 1967 to pursue their motorsport ambitions and their first efforts were concentrated on the race preparation of Peugeot 204 saloon cars. For 1969 they produced a 1300cc front-engined sports coupé based on the running gear of the 204 which gave the team its first taste of international competition by taking part in the Paris 1000 kilometres at Montlhery. The following year WM unveiled a 1300cc transverse mid-engined coupé which took part in the 1970 Tour de France Auto. In 1971 it was entered for a three hour race at the 1971 Le Mans Test weekend but did not start due to a clutch failure.

Five years later a WM raced at Le Mans for the first time with a new chassis conforming to the ACO’s newly introduced GTP rules (the forerunner to the FIA’s Group C class) and powered by a race prepared version of the 2.7-litre PRV V6 engine.

Chassis and engine performance improved year on year so that by the early 1980s the narrow track, slippery bodied WMs were regularly among the fastest Group C cars to run at Le Mans. In 1984 WM briefly grabbed the limelight when, live on French TV, Roger Dorchy took the lead of the race on the opening lap and held it until a brake balance problem half spun him out at Mulsanne Corner, Despite recovering to retake the lead again a recurrence of the brake problem pitched the WM into the barriers at the same corner two laps later.

By the mid-80s Group C competition had intensified to the level where a team such as WM staffed by crew members working in their spare time and vacation time were no longer able to challenge the high budget manufacturer backed teams for outright honours. Realising this, shortly after the 1986 24 Heures the WM team embarked on Project 400 which aimed to capture the Mulsanne speed record.

The car that would be used for Project 400 was based on the WM team’s hard-won experience and would incorporate a combination of new and existing hardware along with some clever and innovative thinking. The first Project 400 car, the WM P87, was based on an existing P86 sheet aluminium monocoque which derived much of its strength from a central backbone structure. A new nose box and side pods were grafted onto the P86 tub to cater for revised cooling arrangements on the newer car.

Whereas the P86 and racecars and their forerunners had front mounted water radiators, the P87s water coolers, together with the turbocharger intercoolers, were mounted at the lower rear of the cockpit area placing them close to the engine thus eliminating the weight of several metres of plumbing. On the rival Porsche 956/962 similarly located side mounted water radiators and intercoolers were fed air by ducts formed in the upper surface of the doors. WM’s low drag approach for the P400 cars dictated a different arrangement. Air was taken in through a frontal opening above the splitter and fed into ducts passing beneath the front suspension and into side pods running down the flanks of the car. Beyond the coolers further ducting turned the airflow inwards and directed it upwards within the engine cover and into a forward facing tube on the roof of the car. At the end of the tube a lateral slot in the low pressure area behind the apex of the cockpit canopy vented the heated air to the atmosphere.

“The cooling system on the Project 400 was very original and with very good reasons,” says WM engineer Vincent Soulignac. “At the end of the air ducts that went from the front of the car between the front wheels and into the side structures under the doors we still had the same air pressure as when the air first entered above the splitter so we had a very high flow rate. The heat exchangers we used also had very low permeability which made them very efficient and meant that we had high pressure air at the entry to the turbocharger.”

The P87 was clothed in body panels developed in a series of Peugeot-financed tests in the fixed floor St Cyr wind tunnel in Paris that took place each Sunday over a four month period during the winter of 1986-87. A 10% scale datum model was used for the tests and up to 25 iterations were evaluated on each tunnel visit.

The bulbous shape of the P87 gave the impression that it had been built on a wider track chassis. Not so, says Soulignac, “At 1850mm wide the P86 was narrower than the maximum permitted width by 150mm. When we designed the Project 400 car we decided that the best way to have a very low drag car was to have the wheels covered by the bodywork as much as possible. The track width of the Project 400 car was almost the same as the P86 but the body was wider by 70mm so that it completely covered the rear wheels. The bodywork also partially covered the front wheels but there were cutouts to allow air to escape from the front wheel arches. The increased body width also allowed the front wheels to turn inside the body.”

The FIA Group C technical regulations at that time stated that the floor of the car had to be flat for a minimum of 1000mm behind the vertical plane of the front wheels limiting the length of the Venturi tunnels, which were exhaust energized, and there was also a limit on their height. “The floor of the P400 car was also flat between the front wheels and there was a small deformation under the front splitter, so small – just 30mm – that you could not really call it a diffuser. Otherwise the splitter was at the same level as the flat floor.

“The drag co-efficient for the P400 cars was between 0.25 – 0.26 and the lift to drag ratio was 2.0. So it had exactly what we wanted – very low drag and not very high downforce. I don’t recall the precise figures but with larger tunnels and a shorter flat floor than the LMP cars have today the P400 cars had much better aerodynamic stability especially over bumps.”

There were two main aero adjustments that could be made at the front of the car. Firstly different length nose splitter panels could be fitted; secondly the team could also adjust the extraction of the air from inside the front wheel arches. “This was very sensitive,” says Soulignac. “It was quite similar in principle to what the LMP cars have today in that area. On our car the bodywork covered the forward part of the front wheels but they were open at the rear and adjusting the extraction of the air in this area had a high influence on front downforce. To make adjustments we had different lengths of small deflectors that were mounted on the inside rear wall of the wheel arch.”

As low drag was a priority for the Project 400 car it might be assumed that the rear wing was used as a trimming device rather an important provider of downforce. “The car could probably have run without a rear wing,” says Soulignac, “but we found it was necessary to achieve a good front:rear aerodynamic balance.”

The wheelbase of the P87 was 150mm longer than the P86, the difference between the two being accounted for by the fact that the P87 had the oil reservoir positioned in front of the engine, which added 70mm and a new bellhousing between the engine and gearbox that added another 80mm.

At the test weekend for the 1987 Le Mans 24 hours the WM P87 was plagued with engine management issues and could rarely complete more than one or two successive laps. “The P87 was the first WM with electronic fuel management,” says Soulignac. “It was a very expensive step for our small team and, to be honest, we didn’t have enough money to make it work properly. Engine management was a big problem for us throughout the P400 project. It wasn’t the quality of the parts, it was the cost and we didn’t have enough funding. When you are a team of unpaid volunteers, the cost of parts is the main expenditure. At that time the cost of technology in Group C was increasing greatly and we couldn’t keep up.”

Despite the engine problems, on one of his few flying laps Dorchy passed through the Mulsanne speed trap at 356kmh (221mph), some way short of the target but the team were nonetheless heading in the right direction. A feeling further reinforced by the fact that subsequently the P87 completed a total of more than 1000 kilometres of trouble-free testing on the short Le Mans Bugatti circuit and at Michelin’s Clermont Ferrand test track which included a one kilometer straight.

Over 250 mph on a public road

On June 4, nine days before the 1987 Le Mans race the speed potential of the P87 was tested again when WM team manager Gerard Clabeaux arranged an attempt on a public road speed record. The car was trailered to a stretch of the St Quentin – Rheims autoroute, near the town of Laon, which had been recently completed but was, as yet, unopened. The record attempt would be covered by the French TV station TF1 which would have a camera on board the P87 and another in a chase helicopter.

As they prepared the car the team realized that it had left behind its fuel and with no service stations on the new road there was no nearby supply. Fortunately a team supporter offered to let the team siphon 30-litres from the tank of his Renault 5. Then Roger Dorchy, the intended driver for the record attempt, was delayed in traffic and with the weather looking threatening Clabeaux turned to Francois Migault, who had come to watch but happened to have brought along his race suit and helmet. He was strapped in to the P87 and on the first run, intended merely as a warm up, Migault passed through the police radar speed trap at 416kmh (258mph) and the record was broken. Although Dorchy did finally arrive a short time later, rain prevented any further running.

On the second practice day for the 1987 Le Mans race the WM teams own speed radar clocked Dorchy in the P87 at 407kmh (253mph) but the ACO system only credited the car with 381kmh (236mph), albeit a new Mulsanne speed record. Dorchy’s vow to officially break the 400kmh barrier in the race was scuppered by and engine failure. The low quality of the ACO’s central fuel supply, which affected a number of cars during the race, killed the P87’s PRV V6 engine after just 13 laps.

When the WM team returned for the 1988 race it had two Project 400 cars including a new P88 version which featured improvements to its chassis, suspension and aerodynamics. The P88 rear suspension changes were also incorporated into the P87 allowing the use of wider Venturi tunnels. Both cars were equipped with full 3-litre displacement engines developing over 900 bhp at full boost as the team again targeted the 400kmh barrier…

The 1988 Le Mans 24 Hours

The 1988 Le Mans race was memorable for the fierce battle between the works Jaguar and Porsche teams that was eventually resolved in the favour of the British manufacturer but will also forever be recalled as the year that the 400kmh/250mph speed barrier was broken by the WM team.

In practice both WMs suffered turbocharger problems despite this the team was again convinced that it had broken the 400kmh barrier with its new car and again the ACO speed radar denied them. In the race itself the P87 came to a premature halt just beyond the end of pit lane with a transmission failure. Coached by his mechanics the driver worked on the car for more than two hours before it was officially retired from the race with 13 laps completed. Dorchy’s P88 was also an early caller at the pits at the start of the race. Engine management and bodywork issues kept the car motionless for the best part of three and a half hours. When the P88 eventually rejoined the race and was finally running cleanly Dorchy received a radio message from Soulignac asking him to increase turbo boost pressure by 100 millibars and he was unleashed on a series of laps aimed at officially breaking the 400 kmh barrier on the Mulsanne straight.

“During practice, according to the ACO radar, we never reached a speed higher than 387kmh,” recalls Soulignac. “The ACO radar system was from Metstar, a French company that supplied police radar systems. The model that was used in practice was the Metstar 206 which was sold as being able to measure speeds of up to 420kmh but we found out that it was badly affected by the vibrations caused by the high noise levels of racing cars. During the two practice days we had discussions with Metstar about this and as a result they told us that for the race they would bring a new type of radar system – the Metstar 208 – which was a prototype that could measure even higher speeds than the 206 and was less prone to the noise problem.

“So the new system was in place when the race started but of course we had our engine management problem early on. A little time after we finally got the car running someone from Metstar came to see me in the pits and said, ‘We don’t understand, your car keeps passing the radar point at 397 or 398kmh (247 – 248mph). You only need 2-3kmh to obtain your record.’ So we knew that the car was capable of setting the record, so I called Roger on the radio and told him to increase the turbo boost pressure by 100 millibars. Then he did three or four laps in which he passed the radar point at 400 – 407 kmh. As 1988 was the year that the Peugeot 405 Turbo was introduced we decided to declare that the top speed was 405kmh. In fact 407kmh was Roger’s best run.”

Some reports of the 1988 Le Mans race claim that the P88 was equipped with special narrow Michelin tyres and that for its record speed laps ducts in the bodywork were strategically taped over. However, according to Soulignac the only difference in the configuration of the car was the increase in turbocharger boost pressure mentioned above which pushed peak power to 910bhp. The exertions of setting the record cost the P88 dearly as afterwards it spent a total of a further 3hr 20min in the pits as the team tried to rectify turbocharger, cooling and electrical issues before the car was retired shortly before 2 am.

Could the car have gone even faster? Soulignac thinks so, “In practice for the 1988 race we ran the car with longer gear ratios and I’m certain that it did more than 410kmh (254mph) but the radar system didn’t register it. We worked out our road speed from the speed of the engine and the gear ratios and we were sure that we made it but there was no one to independently verify it.

“In 1987, with lower downforce, the P87 had reached close to 417kmh (259 mph) on the motorway run. I’m certain that the car ran over 400kmh in the 1987 race and I’m sure it wouldn’t have been a problem to have gone 420kmh (260mph) in the 1988 race…”

Dorchy’s achievement withstood a challenge from the Sauber-Mercedes team in 1989 (one of the Silver Arrows passed through the speed trap at 400kph in practice) before the record was effectively ‘sealed in amber’ when two chicanes were added to the Hunaudières/Mulsanne straight ahead of the 1990 race. Those chicanes remain a feature of the Mulsanne to this day, and the P88’s record-setting run of 253 mph stands unchallenged by the top speeds of recent years, which have rarely exceeded 205 mph.

© 2012 Alan Lis

The black and white photographs for this article were supplied by Alan. Not fully explained in Alan’s text is that the P87 bore the number 51, while the #52 was the P88 variant. The two cars returned in 1989, but suffered a succession of unfortunate events. Both caught fire in qualifying, with the #51 sustaining the more serious damage. The #52 was then rebuilt on the Friday, using parts salvaged from the #51, and only the #52 would take part in the race. A succession of technical troubles hampered the opening few hours, with the mechanics having to work hard to keep the P88 on track. Oil and water pump failures, a dropped valve, and soft brakes, culminated in a tyre blow-out on the Mulsanne. The crew managed to recover from all that, only for the #52 to erupt in flames through Indianapolis shortly after noon on the Sunday, encouraging Pascal Pessiot to make a hasty exit. It would be six years before Welter Racing would return to Le Mans, but 1995 provided another highlight for the small French team, when Welter’s Peugeot 205 Spider-based WR LM95 (below) locked out the front row in qualifying – the first and only time that a single-seater has taken pole for the 24 Hours.