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With the car’s mechanical issue resolved, and a new radar system operating for the race, Roger Dorchy was finally able to, officially, break the 400km/h barrier

Despite completing just 59 laps at the 1988 Le Mans 24-hour race with the number 51, the WM team met its Project 400 target

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, used an existing P86 sheet aluminium monocoque, which derived much of its strength from a central backbone structure. A new nose box and sidepods were grafted onto the P86 tub to cater for revised cooling arrangements on the newer car.

LOW DRAG APPROACH Like the previous P86 model, the P87 was equipped with a front-mounted water radiator. This was laid horizontally, fed by an upward duct and vented into a channel running around the base of the windscreen. WM’s low drag approach for the P400 cars dictated a novel arrangement for the turbocharger intercoolers. Air

With the front bodywork 70mm wider than the front track, the WM’s steered wheels were able to turn inside the overhanging body

was taken in through a frontal opening above the splitter and fed into the ducts beneath the front suspension and into the side pods running down the flanks of the car. After passing through the intercoolers, further ducting turned the airflow inwards and directed it upwards within the engine cover through a forward-facing tube on the roof of the car and into a lateral slot in the low pressure area behind

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 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

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 cut outs to allow air to escape from the front wheelarches. The increased body width also allowed the front wheels to turn inside the body.’

FLAT FLOOR The FIA Group C technical regulations at the 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 energised, and there was also a limit on their height. ‘The floor of the P400 car was also flat between the front wheels and

“the cost of technology in Group C was increasing greatly and we couldn’t keep up”

the apex of the cockpit canopy, where the heated air vented to the atmosphere. ‘The cooling system on the Project 400 was very original, and with very good reasons,’ explains 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

over a four-month period during the winter of 1986 / ’87. A 10 per cent 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 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

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

July 2012 • 37

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