The Sierra RS Cosworth was an attempt in 1983, from recently named Director of Ford Motorsport in Europe Stuart Turner, to rebuild Ford reputation in rallying and circuit competitions. Powered by a 300 hp turbocharged engine designed by Cosworth, and even though it was the only two-wheel drive, it was the car Boreham-based team selected to compete in the group A based 1987 Championship.
C.Sainz/A.Boto, Ford Sierra RS Cosworth, 1988 RAC Rally, 7th
Original Sierra hatchback design proved to generate significant aerodynamic lift even at low speed, so extensive wind tunnel testing was done at MIRA facilities to reduce lift, by a team led by Lothar Pinske, responsible of the car’s bodywork. They started from an Xr4 for the design, which already incorporated a bi-plane rear wing (although the larger plane was located in the lower position), as per the original design Heinz Ostendorf and his team had been refining after 75 days of wind tunnel testing.
Courtesy of Total Car magazine
Ford Sierra Xr4 at Ford Wind tunnel in Cologne, Germany
The final design included a big whale-tail spoiler located half-way up the line of the hatchback, which was hardly accepted by company management and dealers at first sight. However, the new design proved to be very effective by making the car stable at racing speeds, and it was finally accepted with no further discussion. At wind tunnel tests, generated downforce by rear spoiler was estimated to be 17 kgfm at 200 km/h, versus a lift of 52 kgfm without it, that is, a net difference of 69 kgfm.
The car was first presented to the public in 1985 Geneva Motor Show. FIA homologated the car in January 1987 (see Homologation Form here) so the first rally in which it took part was the 1987 Rally of Monte Carlo, driven by Kalle Grundel. Stig Blomqvist also participated, but with a Sierra with a small, simpler rear spoiler.
K.Grundel/T.Harryman, Ford Sierra RS Cosworth, 1987 Monte Carlo Rally, 84th
Best results in its first year were a 2-3 in 1000 Lakes Rally, by Ari Vatanen and Stig Blomqvist, as well as another 2-3 in RAC Rally by Blomqvist and Jimmy Mcrae.
A.Vatanen/T.Harryman, Ford Sierra RS Cosworth, 1987 1000 Lakes Rally, 2nd
In addition to official drivers, the team also gave opportunity to debut in the Championship to a set of young drivers, such as Didier Auriol, Carlos Sainz or Colin Mcrae, what allowed them to attract attention from other manufacturers, such as Lancia, Toyota or Subaru, who gave them the chance to enter into their factory teams in the next years. One of these young drivers, Auriol, drove the car to his only win, in the 1988 Tour de Corse, breaking the dominance of Lancia, who had won all major rallies that year.
D.Auriol/B.Occelli, Ford Sierra RS Cosworth, 1988 Tour de Corse, 1st
C.Sainz/L.Moya, Ford Sierra RS Cosworth, 1988 Tour de Corse, 5th
Poor results in 1989 showed that four-wheel driving was essential to keep the level of the competence, and Boreham decided to start working on the 4×4 version of the Sierra RS, which would be launched by the end of 1990. Colin Mcrae gave the car his last remarkable result by finishing fifth in 1989 Rally of New Zealand, while his father Jimmy was forced to retire due to an accident with another Sierra.
C.Mcrae/D.Ringer, Fors Sierra RS Cosworth, 1989 Rally of New Zealand, 5th
HIstory continues, with the Lancia Delta HF 4WD dominating the post-group B seasons. One of the most special versions of this car was the Deltona, the last winning bid from Lancia.