Cosworth and Ford had resisted pressure to develop a turbocharged Formula One engine for several years, with chief engineer Keith Duckworth sceptical that forced induction was compatible with the spirit of the regulations. By the early 1980s, however, turbo-powered cars were dominant — winning every World Championship from 1983 to 1988 — and the naturally-aspirated DFV family was no longer competitive except through the efforts of specialist teams.
Development of the GBA began in earnest in late 1984. Cosworth initially designed an inline four-cylinder engine derived from the BDA series, using a Ford Escort engine block. After three weeks of testing, incurable crankshaft problems under boost pressure led to the abandonment of this concept. A fresh start was made with a 120-degree V6 configuration, matching the layout used by the most successful turbo competitors. The internal designation GBA was chosen to follow the earlier Cosworth GA, a naturally-aspirated V6 from 1973.
The first engine ran on the test bench in August 1985, and made its racing debut at the 1986 San Marino Grand Prix with the Team Haas entry driven by Alan Jones. The GBA was a compact unit — 450 mm long and 510 mm high — with an aluminium block and cylinder heads, Nikasil-coated cylinder bores, twin overhead camshafts per bank driven by chains, and twin Garrett turbochargers. Electronics were a joint Ford-Cosworth development using the EEC-IV system, with the engineering programme led by a team that included Cosworth's Steve Taylor, Ford America's Jim Coats, and Motorola's Frank Rayo. Only 25 engine blocks were produced in total.
Early in the 1986 season the GBA produced around 700 horsepower in qualifying trim. By the end of the year this had risen to approximately 900 horsepower, placing the engine's performance level slightly above that of Honda and comparable to Ferrari. In the 1987 season, race-trim power reached comparable levels in the second half of the year, and Thierry Boutsen briefly led two Formula One races in the Benetton B187 — at the Brazilian and Mexican Grands Prix.
The compression ratio was gradually increased during development, rising from 6.5:1 to 8.0:1, as the team resolved the tuning and engine management strategies. The GBA used Mahle pistons, a decision retained throughout the programme after early evaluations showed it more cost-effective than in-house piston manufacturing.
Ford awarded exclusive use of the GBA to Team Haas in 1986. The Colnbrook-based team, run by Carl Haas, entered the engine in the Lola THL2 chassis driven by Jones and Patrick Tambay. Results were disappointing — reliability was poor, both drivers retiring frequently, and Cosworth declined repeated requests from the team for more powerful qualifying-specification engines. The GBA was blamed for significant straight-line speed deficits relative to the BMW, Honda, and Ferrari-powered cars of the same era. Team Haas scored six championship points in 1986 and disbanded at the end of the year when sponsor Beatrice withdrew its funding.
Benetton received the GBA exclusively for 1987, fielding it in the Benetton B187 designed by Rory Byrne. Drivers Teo Fabi and Thierry Boutsen qualified regularly in the top five rows and finished consistently through the second half of the season. Fabi and Boutsen each took one third-place finish — Fabi in Austria and Boutsen in Japan after Ayrton Senna's disqualification — along with three fourth places and five fifth places. Benetton finished fifth in the constructors' championship with 28 points.
When the FIA imposed stricter regulations for 1988, reducing boost pressure to 2.5 bar and cutting the permitted fuel load to 150 litres, Ford and Cosworth concluded that the development investment required would not be justified given that turbo engines were to be banned entirely from 1989. The programme was terminated and Cosworth switched focus to the naturally-aspirated DFR and the new HB series V8 for the post-turbo era.
The GBA was a significant if commercially limited programme — the only time Cosworth built a turbocharged engine for Formula One. Its narrow window of competition (1986 to 1987, just 25 total engine blocks produced) meant it never had the opportunity to demonstrate its full potential. The engine was competitive in outright power terms by the end of its life but was hampered throughout by reliability issues and a restricted customer base. The GBA stands as the conclusion of Cosworth's turbo-era chapter before the company returned to its strengths with the naturally-aspirated engines that would dominate from 1989.