Model Page

Ford Sierra Cosworth RS500

Production Run:


Production Date:



Ford Cosworth YBD 16v DOHC


Ghenk (Belgium)

Tickford (UK)


6.4 secs

Max Speed:


The story of the Sierra Cosworth RS500 follows on from the introduction of the RS Cosworth two wheel drive. Fordís intention was to develop an evolution of the previous model with the aim of producing a car that would be unstoppable on the track. The RS500 had been in development since before the introduction of the standard RS Cosworth with the project being headed by Mike Moreton.

Standard RS500 in Black

Standard RS500 in Black

Rules at the time stated that for a evolution of a homologated car to race at least 500 cars needed to be produced and sold, hence the model name RS500. To comply with these regulations Ford signed off the production of 500 cars to be completed by Aston Martin Tickford in March 1987. The car was not officially announced until July 1987 and it was not until August of that year that the car achieved homologation.

The standard Sierra RS Cosworth was good for around 400 bhp on the track, Ford wanted to ensure total domination and had a requirement that the engine be capable of comfortably exceeding 500 bhp in race trim, the engine therefore needed considerable attention.

224 Bhp Cosworth Engine

224 Bhp Cosworth Engine

The Cosworth YBB block used in the Sierra RS Cosworth was upgraded with a thicker walled cylinder block, the new block taking the YBD designation. To provide sufficient fueling a second fuel injection rail was added complete with an extra four injectors providing a total of eight in all. Although present, the additional four injectors did not operate in the road going RS500. To provide enough fuel to the injectors it was necessary for an upgraded fuel pump to be added. The induction system was overhauled and the standard Garret T03 turbo charger was replaced with the larger Garrett T4 unit to generate greater boost levels, the intercooler was also enlarged. The larger T4 unit had the effect of increasing turbo lag on the road going cars but was essential to the success of the racing project. To maintain the engine under the additional stresses generated by the extra power the cooling and oil systems were up-rated. Finally, the engine management system was remapped.

The bodywork was not left untouched, the front bumper was redesigned to promote cooling and the front spoiler lowered to improve aerodynamics. The front fog lamps were deleted and replaced with intake grilles and cooling ducts for the brakes. To increase the aerodynamic down force produced by the model a second rear wing was added below the whale tail that was taken from the Sierra 2.0i S and a 30 mm lip added to the main rear wing. These changes increased the drag coefficient slightly over the base Sierra Cosworth. The alloy wheels were upgraded to 15Ē cross lattice shod with Dunlop D40 tyres. In an attempt to keep costs as low as possible the car was only available in three colours Ė Black, White and Moonstone Blue, the car was completed with discrete RS500 badges on the front lid and boot lid.

Sierra RS500 Cosworth on the Track

Sierra RS500 Cosworth on the Track

The suspension layout was slightly revised from the standard RS Cosworth with the rear beam being enlarged with additional mounting points (unused on the road cars) to allow for a longer wheel base to be used for racing. The car remained rear wheel drive only.

The interior cabin remained as per the standard RS Cosworth with only one trim specification available.

The car was not an instant success in Motorsport with the engines prone to blowing the head gaskets, once this problem had been overcome the car quickly established itself as the dominant force on the track annihilating the competition. The success of the car ultimately was its downfall, the later Sierra RS500ís helped Ford to win the only World Touring Car Championship that was held at the time and the car enjoyed 40 consecutive victories in the BTCC. To bring an end to Fordís dominance the rules were changed limiting the power output of the cars Ė at this time the Sierra RS500 Cosworth was generating around 550 bhp.

The Facts


Ford Cosworth YBD Turbo Charged





Compression Ratio:


Fuel System:

Weber Marelli Fuel Injection

Maximum Power:

224bhp @ 6,000 rpm.

Maximum Torque:

206lb/ft @ 4,500 rpm.


Manual 5 speed.

Top Gear:

22.9mph per 1000 rpm.


Servo Assisted Ventilated Front Discs / Solid Rear Discs

Kerb Weight:


Max Speed:

154 mph


6.4 secs