Factory Bench-Tested Ford YBD RS500 Engine #YBD0628

The Sierra RS Cosworth might have been the first Ford to be honoured with the Cosworth name, but the relationship between the two companies dates back to the 1960s when the American car producer funded the development of a 3-litre V8 engine for Lotus' F1 car. The resulting V8, known as the DFV, then went on to be a dominant engine in Formula 1 for over a decade, winning 155 Grand Prix.

Despite reigning supreme on track and in rallying throughout the decade, by the end of the 1970s, Ford’s motorsport dominance was on the wane. Even the once all-conquering Ford-Cosworth DFV Formula 1 was starting to lose out to more modern turbocharged units. This was painfully obvious when a Ford VIP contingent visited the 1983 British Grand Prix at Silverstone, where a Touring Car race supported the main event and Ford bosses, Stuart Turner and Walter Hayes, were dismayed to witness a group of Capris being humbled by SD1s with Rover V8 power.

The solution was again to be found with the engineers at Cosworth who had previously developed a four-cylinder engine for Ford's racing and rallying saloons in the late 1960s and 1970s. The Mk1 Escort RS1600, which replaced the Lotus-powered Twin Cam Escort, had a 1,600cc engine with a 16-valve head designed by Cosworth called the 'BDA'.

The formula for the Sierra wasn’t dissimilar to that of the earlier homologation Escorts and Cosworth and the trusted cast iron block from Ford’s single-overhead cam, the T88 Pinto that was used in the Escort RS2000, was utilised to form the basis of this new engine. Code named 'YAA', Cosworth designed an aluminium head to suit the Pinto block with two belt-driven cams operating 16 valves; eight 35mm diameter inlet valves and eight 31mm exhaust. Compared with the basic Pinto, almost everything changed except for the cylinder block itself and the new head and valve gear were matched to a new steel crankshaft, rods, pistons, and sump, and hydraulic valve lifters were a given. A turbocharger was always part of the plan and a Garrett AiResearch T3 with an intercooler were selected boosting power to 201bhp at 6,000rpm and 205lb/ft at 4,500rpm, in road car spec.

With a new facility to produce the production-ready version (now with the 'YB' prefix), the first prototype started test-bed work in Northampton in June 1984 although the first engines and test cars didn’t go to Weber-Marelli in Italy until September 1984 before subsequently being 'signed off' by mid-1985.

First utilised in the 3-door Sierra RS Cosworth of 1986 - introduced for homologation to allow Ford to go 'Group A' Touring Car racing - the new production 1,993cc YBB engine proved to be legendary, both on road and track. When the ruling allowed for an 'evolution' upgraded model to compete, spawning the RS500 Cosworth, the YB engine stepped-up too, the grateful recipient of further development.

To cope with the requisite extra horsepower required, the original YBB motor was switched to an uprated 'YBD' unit which featured a reinforced block (still cast-iron) with thicker walls (note, there are two main types of YB block - known as the 205 and the 200, the latter is a thicker-wall design and was found in 4 x 4 versions, such as the Escort and 1990 Sapphire; the RS500 block was also a thick-wall design but stamped 205, recognisable by its smaller core plugs). Other differences included a bigger Garrett AiResearch T04 turbo plus a larger air-to-air intercooler, pressurised oil-cooled pistons, uprated oil, water and fuel pumps and beefier (orange) air hoses for the radiator and turbo, and a re-mapped ECU.

Ford pushed the limit of the Homologation rules to the maximum for the RS500 and the road car featured components that weren’t at all functional but allowed legal modifications on the race cars. The RS500's Cosworth YB engine had an inactive secondary injection system fitted so, when activated on the race cars, their engines could swallow greater amounts of fuel and produce more power (with a different engine map and the second injectors squirting fuel, race RS500s made an 'easy' 485bhp and it didn’t take much more before the engine was putting out 525bhp).

In addition, the YBD’s induction system was reconfigured with a bigger intake plenum which, along with a new secondary fuel rail, required one corner of the battery tray be cut away for installation, and a slightly different thermostat housing and alternator bracket. On the road cars, the RS500's power rating went from 201bhp to 224bhp at an unchanged 6,000rpm. Peak torque was the same as the regular Sierra RS Cosworth: 204lb/ft at 4,500rpm.

Although undoubtedly successful before, the Ford Sierra became really dominant when the RS500 took to the circuit, winning the 1988 DTM championship, the 1989 Spa 24 Hours, the 1988 and 1989 Bathurst 1,000km, the 1988 and 1989 Australian Touring Car Championship, the 1988 and 1989 Japanese Touring Car Championship and the 1990 British Touring Car Championship.

The engine presented here is a Cosworth factory, bench-tested YBD unit, #YBD 0626, designed and built for an RS500 road car. Tested and signed off by Cosworth, confirmed by a tag, it's understood to be one of the very last YBD engines to leave the factory. We understand that it has always been complete (i.e. never as separate components), has never been apart, rebuilt nor ever installed into a car, being sat on its plinth since manufacture. All the factory elements appear to be present and correct, the stampings included, even down to the original FRAM oil filter!

Meticulously kept - in pride of place even - alongside his two RS500 cars, it has been owned by our vendor for last 14 years. He sourced it from an ex-pat Ford aficionado living in Malta who had acquired it previously in the UK (some 6 years before). Rumour has it that only a handful of unused YBD engines still exist.

For the serious collector or enthusiast, this 'jewel' of an engine is supplied with a bespoke glass display case and is now ready to be appreciated by its next custodian; what an opportunity.

N.B. Please note this lot will be sold with a buyers premium of 20% plus VAT as per our usual memorabilia terms.