In 1990, Mazda UK made a big splash by announcing a "factory" turbocharged version of its MX-5, in collaboration with Brodie Brittain Racing (BBR). The stated goal: to outpace independent tuners with a fully homologated engine conversion, designed to retain the manufacturer’s warranty.
Such a move was rare. To achieve it, Mazda called on several renowned specialists, Turbo Technics, TWR, and BBR to develop a turnkey conversion that could be installed directly on new cars or as a kit for existing vehicles. They were set a single non-negotiable condition: to retain the original 9.4:1 compression ratio, this for homologation reasons and to avoid disassembling the engine block. (9.4:1 is a high ratio and uncommon for a turbocharged engine.)
BBR's proposal was the one selected. Their kit was considered to offer the best compromise between performance, reliability, ease of installation, and compliance with Mazda’s standards. BBR’s approach also ensured that the full manufacturer’s warranty remained valid, a rare confidence for a modification of this kind.
BBR left nothing to chance, conducting 2
At the time, Mazda envisaged only one in 10 buyers opting for the turbo version, and production was to be limited to 2,500 units per year. In the end, 850 kits were produced (between November 1990 and September 1991), of which 250 were installed directly on new MX-5s (available only in red, black, or white).
Mazda did not offer any suspension modifications to the base MX-5, but BBR proposed an optional kit. The BBR version could also be equipped with an optional, elegant, rear spoiler, while the BBR Turbo identification badges were standard. The only £1,000 option was a set of five-spoke OZ wheels specific to the BBR fitted with 15” Dunlop D40 tyres was available. A limited-slip differential was also available for £621.
00 hours of engine dyno testing and 150 hours of continuous road testing, both on track and in urban settings. This comprehensive homologation programme underscored BBR’s dedication to the project, working in close partnership with Mazda for official validation.
The BBR turbo conversion kit included some 68 specific parts. The main modification was a high-temperature alloy exhaust manifold leading to the turbocharger (water-cooled) with an integrated wastegate. Special cast aluminium parts, exclusive to the BBR MX-5, directed the air-to-air intercooler flow. Competition-grade hoses were custom-made for the power steering, oil system, and cooling system to handle the higher temperatures generated by the turbocharger.
The £3,700 conversion also included a modified oil pan to lubricate the turbo and a larger thermal shield for the manifold. The standard catalytic converter was kept. The use of 98-octane unleaded fuel was recommended, but a switch on the dashboard allowed for running on 95-octane.
But the most important change, beyond the turbo itself, was BBR's revised engine management system. This auxiliary electronic control unit used a three-dimensional map to manage fuel injection, ignition timing, and boost pressure. It was complemented by a boost gauge on the dashboard. Installing the conversion took about 12 hours workshop time.
Power: 150hp (vs. 115hp stock)
Torque: 154lb-ft at 5,500rpm (+50%)
0 to 100 km/h: 6.8 s (vs. 9.1 s)
Top speed: 210 kph (vs. 183kph)
For true power enthusiasts, BBR also offered a “phase two” conversion pack capable of delivering up to 240hp.
From a driving perspective, the preservation of the original compression ratio meant that turbo lag was virtually non-existent so ensuring immediate throttle response even under dynamic driving conditions. On the road, the BBR Turbo retained the lively and communicative character of the MX-5. The ultra-precise steering guaranteed perfect road feel. The gearbox was stock and as delightful to use as ever.
Even with the increased power, the brakes remained strong and reassuring, offering better feedback than those on the Lotus Elan SE, its premium counterpart — which came with a £3,500 premium.
However, not everything was perfect. While the car was agile, the rear end was livelier: oversteer was easily triggered, but more difficult to control, especially in rapid sequences. Frequent overcorrection was required, making the car less predictable than the naturally aspirated version.
Different tyres were deemed partly to blame. Nevertheless, the BBR was not as easy to handle as a standard MX-5, renowned for its user-friendly driving dynamics.
In testing, average fuel consumption was recorded at 24.1 mpg (about 11.7ltr/100 km). A smoother driving style, especially on highways could improve the figure to around 28mpg / 10ltr/100 km.
This official Turbo marked a turning point in the MX-5's history, halfway between a gentleman's car and a civilized track toy.
