The Escort Cosworth
Escort Cosworth GrpN and Grp A
Ford cars have been involved in rallying since the late 60s. Not much success though on their account although many individual victories were achieved, most of them due to individual and private efforts until the early 70s when the first, legendary, Ford to race in the World Rally Championship the Escort RS (Mk I and Mk II series) 1600 then 1800 and finally 2000. Juha Kankkunen,Ari Vatanen and Stig Blomquist all started their racing careers in that car. The situation changed somewhat in the late 80s when the Ford motor company associated with its old partner Cosworth Engineering started producing cars that could be considered for use in world rallying. The name Cosworth, made-up from the two founding engineers of the company Mike Costin and Keith Duckworth, is world famous in racing. The Cosworth company has since been split in many entities and, while the engineering part is now owned by Audi, the Cosworth Racing part is still owned by Ford. The Ford Cosworth series of cars spanned from 1986 to 1996 and were based on the old but solid Ford Pinto derived four cylinder cast iron block powered by an aluminum 16 valve head . The engine consisted of in-line 4 cylinder units with 2 overhead camshafts and was blueprinted from its origin as a supercharged unit using Garrett turbochargers. The engine had a 2 litre displacement and its output was initially 204 Bhp. The latest models had units with up to 227 Bhp output.
The Escort Cosworth YBT engine
(Notice the blue camshaft cover)
The colour denotes the engine type:
• Red for versions running on premium gas
• Green for those running on unleaded
• Blue for those running on unleaded
gas with a catalytic converter fitted
The YB series of Cosworth engines are "super square", short stroke i.e. bore is greater than stroke (90,8 x 77,0 mm in this case) thus advantaging high rev output rather than low end torque as is the case in long stroke engines. It's a fact that all Cosworth engines, even heavily modified ones, require to be operated in relatively high revs in order to be responsive. These fantastic, race bred engines are very conservatively rated in out-of-factory cars at approx. 220Bhp. They easily withstand outputs in excess of 300Bhp with little to no reliability problems .
First in the Ford Cosworth car series was the "Homologation Special" RS500 (224 Bhp in its street version), a car based on the Sierra chassis, easily recognizable by its huge rear spoiler (which made the Ford marketing department go crazy but was finally imposed by the development team). The RS500 was a 2 wheel drive car (the rear wheels). The RS500 was mainly destined to track racing and, as its name suggests, was produced in 500 samples. It was followed by a new Sierra (a.k.a. Sapphire) based Cosworth powered car which was heavily involved in world rallying in the hands of drivers such as Miki Biasion and Francois Delecour. The Sierra Cosworth was, initially, a 2 wheel drive car very similar, mechanically, to the RS500. Later a 4 wheel drive version was introduced which used the classic Ferguson layout (2 Viscous coupler equipped differentials are used, one between the front and rear axles and one in the rear axle). The commerce (street) version was fitted with a 204 Bhp output unit and had a torque distribution was 34% in the front and 66% in the rear wheels. Most competition cars had a 50-50 torque distribution (although this could vary with some cars using 34/66 F/R distribution on tarmac).
The Sierra RS Cosworth had some success but did not score a single win in the WRC in its 4WD version (it did score 1 win in its 2WD version) and was not really able to compete with the Lancia Integrale, which was dominating the rallying world at the time, especially because of its size and weight.
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