Williams FW11

The FW11 won nine races of the 1986 Championship, with both drivers challenging for the Drivers' title before losing to Alain Prost in the final race in Australia. The FW11B won nine races in 1987 and Piquet secured the Drivers' title despite winning fewer races than Mansell. Williams won the Constructors' title comfortably in both years. The FW11B was the last Williams car with a turbocharged engine until the FW36 in 2014.

The FW11 won on its debut at the Brazilian Grand Prix with Piquet. Mansell then mounted a title challenge, winning four races. The season was overshadowed by the near-fatal road accident of team founder Frank Williams, which demoralised the team; Williams survived but became quadriplegic, with the British Grand Prix marking his first appearance in the Williams pit lane during rehabilitation. Patrick Head stepped up to manage the team during Williams' absence, a period that reportedly contributed to internal friction between the two drivers.

Mansell's championship campaign ended with a dramatic tyre blow-out in the final race in Australia at a moment when finishing third would have secured the title. The accumulated points of both Piquet and Mansell were sufficient to win the Constructors' Championship.

Both Piquet and Honda reportedly left Australia unhappy with team management. They believed that Piquet had been signed as the undisputed number one driver — citing Frank Williams' public declaration that he had signed "The best driver in the world" — and that the team had failed to honour that arrangement by not ordering Mansell to yield during races.

The FW11 was updated for 1987 as the FW11B. Honda was simultaneously supplying Lotus with the 1986 RA166E engine (rather than the 1987 RA167E used by Williams), which helped Ayrton Senna mount a consistent challenge. Piquet finished in the points in every race except San Marino — where a heavy crash at Tamburello during Friday practice left him with a sore ankle and he was prevented from starting by FIA Medical delegate Prof. Sid Watkins — Belgium, and Australia. Mansell scored six victories, including a come-from-behind win at the British Grand Prix at Silverstone where he passed Piquet with three laps remaining, but suffered more unreliability than his team-mate. Piquet's third world title was secured after Mansell crashed heavily during practice for the Japanese Grand Prix.

The FW11B developed active suspension during 1987, referred to as Williams Reactive Ride. Mansell did not participate in its development, having experienced an earlier version on the Lotus 92 in 1983 and declaring no confidence in the system. Development was led by Piquet and Dernie, with engineers Paddy Lowe and Steve Wise designing the electronic computerised system. The first hydraulic prototype was fitted to a 1984 FW09; Piquet found it rode smoothly but handled badly, prompting a redesign. In a race simulation at Imola, Piquet completed 59 laps some three minutes faster than Mansell's winning time from the Grand Prix earlier that year, though he was the only car on circuit.

The system was renamed Reactive Ride to avoid using the Active Suspension name, which Lotus held copyright over; the Williams version was described as lighter, less complicated, and less power-hungry than the Lotus equivalent. Its race debut came at the Italian Grand Prix at Monza, where Piquet used less wing, recorded the highest speed of the 1987 season at 218.807 mph (352.135 km/h), started from pole, and won ahead of Senna's Lotus. Mansell did not try the reactive car in a Grand Prix weekend until the following race in Portugal. Plans to introduce a semi-automatic transmission in 1987 were not realised.

The FW11's Honda engine was noted for its outright power and fuel economy, described in the corpus as superior even to the TAG-Porsche units used by McLaren. Over two seasons the FW11 and FW11B accumulated 18 wins, 16 pole positions, and 278 points.

The FW11B was the last Williams car powered by Honda. During the 1987 season Honda announced it would move to McLaren from 1988, despite a year remaining on the contract. The reported reasons were Honda and Piquet's dissatisfaction with Williams for allegedly failing to honour Piquet's number one status in 1986, and the team's earlier refusal to replace Mansell with Satoru Nakajima (Nakajima subsequently raced five full F1 seasons with Lotus and Tyrrell, scoring 16 points from 74 starts with a best finish of fourth). Mansell remained contracted to Williams through 1988 and stayed with the team; Piquet announced during practice for the Hungarian Grand Prix that he would join Lotus in 1988 as their undisputed number one driver, remaining with Honda. An interim car, the FW11C, was used for testing purposes to evaluate the Judd V8 engine ahead of the FW12 in 1988; it was never raced.

This article is based solely on the supplied corpus. No external sources were consulted; claims that could not be substantiated against the corpus were omitted under the drop-the-claim rule.