Ford Sierra RS Cosworth
Back in 1985, Stuart Turner, newly appionted head of Ford Motorsport in Europe was tasked to take a look at what could be done to try and re-claim some of Fords previous success in the field of Rallying and Racing. Turner, quicky realised that the current batch of competition cars were just not up to the job, the Mk3 Escort was front wheel drive and would never be successful in rallying, a sport that Ford had dominated previously with the Mk1, and Mk2 Escorts.
After a conversation with Keith Duckworth of Cosworth revealed that Cosworth were developing a 16 valve head as an aftermarket performance part for the new Sierra, Turner saw that a tie in with Cosworth would be perfect both from a competition and marketing perspective, Ford had enjoyed a succesful partnership with it’s Lotus/Cortina, the Sierra/Cosworth would hopefully be as lucrative.
A new 2.0 litre 16 valve Turbocharged unit (204bhp) mated with the new Sierra road car would be homologated for Group A, and in 1986, the RS Cosworth was born. 5545 cars were built with a further 500 being sent to Tickford to be converted to the RS500.
The RS 500 was the ultimate version of the Sierra Cosworth. Built to be unbeatable on the track, the Cosworth engine was uprated with a thicker walled block, larger turbo, larger intercooler, uprated fuel pump feeding a second set of injectors and a new induction system. The upgraded engine produced 224 bhp in roadgoing form, and far more than that in race trim. Subtle differences in the exterior including a second lower spoiler at the rear and an extra cooling duct at the front distinguished the Rs500 from the standard Cosworth.
A condition of the partnership with Cosworth was that Ford would buy 15,000 engines, many more than they actually needed to homologate their cars. So, once the original Sierra Cosworth run had ended, the 4 door Sapphire model got the Cosworth treatment. Initally a rear wheel drive car producing 204 bhp, as per the original Sierra Cosworth, in 1990 a 4×4 version was introduduced.
The Sierra Sapphire Cosworth 4×4 was developed to go rallying. Since the ban on Group B rallying (Ford developed the mighty RS200 Group B car), manufcturers were left with the option of competing in Group A. The rear wheel drive Cosworth had the power, but on the loose gravel special stages lost out on grip to the 4 wheel drive competitors such as Lancia. The only 4×4 Ford had was the XR4i, which while having a good chassis lacked power. Ford resorted to running the XR4 on the gravel and the rear wheel drive Cosworth on tarmac until the introduction of the Sapphire 4×4 in 1990.
The Sierra RS Cosworth 4×4 was never really as sucessful a rally car as ford had hoped. But as a road car the Cosworth 4×4 was a great success. Ford claimed the new engine was modified by 80% and now produced around 220bhp. Couple that with the rear biased 4 wheel drive transmission and the 4×4 Cossie was a real scorcher.
Generally speaking, the original 3 door Cosworth is worth more than the later Sapphire models with the exclusivity of the RS500 commanding the most, up to £30-40k for good examples.
thefordsierra.tripod.com RS Coswoth history page
RS Owners Club RS Info page
RS Owners Club Cosworth ’85-87
RS Owners Club RS500 info
RS Owners Club Sapphire RS Cosworth info
RS Owners Club 4×4 RS Cosworth info
RS-500.ik.com RS 500 History
Cars.uk.msn.com RS Cosworth Hero or Zero
RS500Cosworth.com Buyers guide
Classic And Performance Car Sierra RS Cosworth Buyers Guide
Autocar Sierra RS Cosworth Review (1986)
Auto Express Review
Auto Express RS Cosworth 4×4
Pistonheads Heroes Sierra RS Cosworth
RS Owners Club Forums
Passion Ford Rebiuld Thread
Wheeler Dealers Cosworth Episode