The McLaren MP4/3 was the car with which the McLaren team competed in the 1987 Formula One World Championship. The car was designed under the leadership of long-time McLaren engineer Steve Nichols, in collaboration with Neil Oatley, Gordon Kimball, Tim Wright and Bob Bell. It was also the last McLaren car to be powered by the TAG-Porsche turbo engine that had been introduced in 1983. The car was driven by double World Champion Alain Prost, in his fourth season with the team, and Stefan Johansson, who moved from Ferrari.
Design
The MP4/3's aerodynamics were completely different from the MP4/2, and the car appeared much more low-slung, to take advantage of the maximum fuel capacity limit of 195 litres, rather than the 220 litre limit in effect from 1984 to 1985. With addition of side-ducted radiators, the car's basic exterior shape was all-new and sleeker than its bulbous looking predecessor with the only visual reminder of the car being its nose section, though this too had been re-designed and was in fact lower and approximately 10% smaller. The suspension set up of the new car was virtually identical to the MP4/2C
To many, the MP4/3 seemed to have been designed along the lines of the lowline Brabham BT55 used by the Brabham team in . Brabham's long time designer Gordon Murray had joined McLaren in 1987 as its new Technical Director taking over from Barnard and this led to the popular belief that he had played a major role in the design of the new look McLaren. However, team manager Jo Ramírez downplayed Murray's involvement in the design of the MP4/3, saying that the BT55's design had no bearing on the car and that Murray had primarily been in charge of quality control. However, Murray himself has since said that this car, and its successor the McLaren MP4/4, were designed using his original Brabham BT55 drawings as a base (as they were legally his, Murray had brought the BT55's drawings with him to McLaren). The claim has since been disputed by engineering director Steve Nichols.
Engine
The engine was the same 1.5 litre, Porsche built, TAG funded and badged twin-turbo V6 engine that had so successfully powered the MP4/2, but with slight changes in compression and engine balancing, to cope with not only the new reduced fuel limit, but also with the FIA's mandated pop-off valve which restricted turbo boost to 4.0 bar after turbo charging was unrestricted prior to 1987.
Success
There were three wins in 1987 with the MP4/3 by Alain Prost at Grand Prix of Brazil, Belgium, and Portugal. Stefan Johansson managed a few podium places, but he would be replaced in 1988 by Ayrton Senna. McLaren still managed to finish 2nd overall, with 76 points, in the Constructor's Championship. The MP4/3 represented the pinnacle of the development of the McLaren TAG-Porsche partnership. The Porsche-TAG engine featured an updated Motronic 1.7 engine management system, and now produced in race trim and up to in qualifying.
Although a number of teams, notably Benetton with their Ford V6 turbo and Arrows with their 4 cyl Megatron turbo (formerly the BMW turbo), encountered problems with the pop-off valve during 1987 when it would often come in lower than the 4.0 bar limit thus giving less horsepower, McLaren got around this by generally setting their TAG's turbo limit at 3.6 bar in 1987. This also allowed McLaren the advantage of better fuel economy.
Even today the MP4/3 is still considered to be one of the most powerful F1 cars ever made, since turbo boost pressure would be further reduced to 2.5 bar in , reducing the power output of the turbo engines to around in a bid to make the naturally aspirated cars more competitive. Turbocharged engines were then banned completely in , so the turbo era in Formula One may remain possibly the high-water mark for horsepower levels in Formula 1.
The MP4/3 was also the car with which Prost won the 1987 Portuguese Grand Prix to become the driver with the most wins in Formula One history beating Jackie Stewart's record of 27 wins which had stood since Stewart retired at the end of .
The MP4/3 was the last McLaren Grand Prix car to use the TAG-Porsche engine. Its successor, the highly successful MP4/4, would be powered by the Honda V6 turbo.
Chassis log history
Five new MP4/3 cars were moulded from carbon fibre with assistance from Hercules Aerospace, as since the creation of the all-new MP4/1 in 1981. The chassis numbers, 1 through 5, were used throughout the year, with three new cars ready for the first race in Brazil.