As 1980 drew to a close, several things happened that affected the direction in which BL Motorsport was headed. Firstly, BL Cars announced that it would cease production of the Triumph TR7 sportscar that had been the mainstay of BL Motorsport’s rally programme since 1976. On the racing side, the new Rover 3500 programme within the British Touring Car Championship had resulted in several wins and, for development, it was agreed that the Rover squad would share a test session at Paul Ricard with Williams Grand Prix Engineering who were BL-sponsored. Amid much publicity, BL Cars had just launched their new small car, the Metro, and FISA had announced that the new Appendix J would take effect from 1982, thus allowing Group B cars to compete for the FIA World Rally Championship.
It was inevitable that during the dark winter evenings in the south of France, the two groups of engineers should talk of a new rally car for BL based on the Metro. These thoughts became reality in February of 1981 when a deal was struck for Williams’s engineers under Patrick Head to design and build a prototype.
The first issues that had to be decided were the engine and the layout. The Rover V8 was too big, but there was a Honda V6 in the pipeline, destined for the new Rover 800. Thus, it would be a V6, and the original plan was to have the engine in the front driving a transaxle at the rear. This was remarkably similar, though without the turbocharger, to the Ford RS 1700T that was also under development at the time. Then two things became clear. The first was that in a small car like the Metro, accommodating even a compact V6 in the front would place the seating position of the crew almost over the rear axle. The second was that, already in its debut year of 1981, the Audi Quattro with its four-wheel drive was re-writing rally car concepts.
By the middle of 1981, the Metro’s design saw the engine moving to the centre of the car and facing backwards with the gearbox in front of it and the step-off unit feeding shafts to front and rear differentials. With no immediate sign of the Honda engine and their Formula Two engine being ruled out on the grounds of being too intractable for rally use, it was decided to create an interim V6 engine by cutting two cylinders out of the Rover V8 and then welding the parts together again to make a V6. This would result in an engine of about two-and-a-half litres capacity.
Naturally, the question arose whether to use forced induction that seemed to be an essential part of the Quattro’s success. However, given the Metro's small size, packaging a turbocharger or supercharger plus all the intercooling and provision for heat dissipation would have been impractical. And if the V6 had stayed between 2.5 to 3.0 litres – the new Honda V6 was going to be 2.5 litres –, the turbocharging coefficient of 1.4 would have elevated the Metro into a class where its minimum weight would have been 1,100 kilograms. Most rally cars of the Group B era with forced induction engines eventually settled on engine capacities below 1,785cc so that their minimum weight was a mere 890 kilograms. In any case, in the early 1980s, electronic control of forced induction engines was such that they did not respond readily in the way that a normally aspirated engine could do.
One problem for the Metro programme was the lack of resources or, in plain words, finance. The company was going through a difficult time with Sir Michael Edwardes sorting out the industrial relations while senior managers strived to solve the development and marketing problems. In 1982, the company was renamed Austin Rover Group with Jaguar and Unipart becoming independent; moreover, the MG name was revived. Thus, the Metro rally car became the MG Metro 6R4 – standing for six cylinders, rally and four wheel drive – while its interim engine was known as the V62V – a vee-six with two valves per cylinder. The financial situation was helped when Harold Musgrove, now the chairman of ARG, decided that motorsport should be better supported and that it should report to Mark Snowdon, ARG’s Managing Director.
Long development period
By October 1981, the first of five V62Vs was running on the dynamometer, but it took most of 1982 to design and manufacture the transmission, using all of the expertise within Williams plus a little help from people like Mike Endean and Robin Herd. The first fully functioning car turned a wheel at the beginning of February 1983. It was delivered to ARG Motorsport on February 7th, and testing got under way immediately. Security was achieved by using nearby Chalgrove Airfield and then ARG’s own facility at Gaydon. It was at Chalgrove on a frosty morning in March that Steve Soper, pressed into service from the Rover racing team as a test driver in the absence of Tony Pond, had the dubious honour of being the first person to put a 6R4 on its roof…
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by John Davenport