Sierra Sapphire RS Cosworth – 1990

Sierra Sapphire RS Cosworth

Sierra Sapphire RS Cosworth

The Sierra Sapphire RS Cosworth 4×4 sets new standards of excellence in the super-car league. From the aerodynamically contoured front air dam to the neat louvred air intakes in the bonnet and all the way back to the low-profile rear wing and the big-bore exhaust.

 

The permanent four wheel drive provides outstanding road-holding allowing the car’s high potential to be used to the max. The powerful twin-cam 16-valve turbocharged Ford Cosworth engine has an output of 220PS, giving a top speed of 240km/h. Huge amounts of torque-throughout the rev range-making the car exceptionally flexible.

The slick 5-speed gearshift was matched to permanent four-wheel drive, for out standing traction and handling. The big, four wheel disc brakes have electronic ABS control for ultimate reassurance. The eye-catching 15” alloy wheels were fitted 205/50 low-profile tyres to make the most of four wheel drive performance. And the all-independent suspension features up rated springs and gas shock absorbers for excellent stability.
There’s a larger intercooler, for even better charge efficiency. The inlet manifold had been revised to give improved turbo cooling. Peak torque is 290 Nm at only 3500 rpm, 80% of the maximum torque is available from 2300rpm right up to the rev limit at 6800 rpm. This is the key to Sierra Cosworth’s exhilarating performance.

Sierra Cosworth 4x4 engine

Sierra Cosworth 4x4 engine

The water-cooled Garrett AiResearch T.03B turbocharger, spinning at up to 120,000 rpm, forces intercooled fuel/air mixture into the cylinders at pressures up to +0.7 bars.

For higher engine efficiency, the compressed air is first cooled in an air-to-air intercooler before passing through the inlet manifold tracts. The turbocharger is wastegate controlled by the Sierra Cosworth’s integrated engine management system, providing exhilarating performance with virtually undetectable turbo lag, for immediate driver response. Twin overhead camshafts operate four large-diameter valves per cylinder via hydraulic self-adjusting tappets. The compression ratio of the pentroof combustion chamber is 8:1. The special forged aluminium Mahle pistons incorporate a shallow recessed bowl in the crown. Short duration cam timing gives minimum overlap for high efficiency.

One of the keys to the Cosworth engine’s performance is its unique electronic engine management system, developed in association with Weber Marelli. The system manages the multi-point fuel injection, electronic ignition and the turbo boost strategy. Sensors throughout the engine feed information to the central micro-processor, which instantaneously computes the optimum combination of ignition timing, fuel injection and turbo boost pressure.

Sierra Cosworth 4x4 interior

Sierra Cosworth 4x4 interior

The all-round independent suspension combines a firm ride with very good handling and high-speed stability. Front and rear anti roll bars help with flat cornering.

 

To enable maximum effective use of the engine’s performance, the Sierra Sapphire RS Cosworth features Ford’s advanced four-wheel drive system. Rigorously engineered to provide formidable handling and traction in all conditions, the system gives a permanent 34:66 front: rear torque split, designed to match ideally the balance of the car and give responsive, reassuring handling. Viscous-coupled limited-slip differentials were fitted, centre and rear, to help maintain grip in slippery conditions. Ultra-low profile 205/50ZR tyres were fitted on distinctive 7 inch alloy rims’, allowing the car’s very high cornering abilities to be safely explored. Variable-ratio power-assisted steering is standard equipment giving lightness for parking, but retaining feel at high speed.

The four body colour choices were:

  • Diamond White
  • Magenta
  • Flint Grey
  • Moonstone Blue