Model Page

Sierra Sapphire 4x4 RS Cosworth

Production Run:


Production Date:

1990 - 1992


Ford Cosworth YBG


Ghenk (Belgium)


6.5 secs

Max Speed:

151 Mph

The Sierra RS Cosworth 4x4 replaced the outgoing Sapphire RS Cosworth 2 wheel drive, the car was released in an attempt to make Ford competitive within the World Rally Championship once more. Based on the Sapphire 4 door body shell the car features a Ferguson sourced four wheel drive system coupled with a revised version of the Cosworth engine that was said to have around 80% of itís parts changed from the 2 wheel drive Sapphire Cosworth.

Sapphire Cosworth 4x4

Sapphire Cosworth 4x4

To mount any kind of challenge toward the WRC title it was apparent that Ford needed to follow in the footsteps of the Lancia Delta Integrale and Audi Quattro and launch a four wheel drive model. In 1987 Fordís Motorsport division had been investigating the possibility of producing such a vehicle but it was deemed that it would not be possible until 1989 when the Borg Warner T75 gear box would first become available. The Motorsport division wanted to use the 3 door shell in which to house a four wheel drive system but Fordís management overturned this decision opting to use the four door Sapphire shell as it was deemed to have more appeal to potential buyers.

Ford claimed that 80% of the engines parts were modified in the Cosworth YBG engine that was used in the vehicle, the engine was readily identifiable by the Green engine top that identified the car as being environmentally friendly due to the addition of a catalytic converter. Changes included the use of a stronger block that is known as the 200, an up-rated strengthened head and stronger pistons with a new gudgeon pin location to reduce piston slap. A revised cast iron exhaust manifold was installed along with a 25% larger air to air intercooler to increase the charge density. The changes helped increase the output of the vehicle to 224 bhp @ 6,250 rpm and 214 lb/ft @ 3,500 rpm, this increase in power helped offset the additional weight of the four wheel drive system.

Sapphire Cosworth 4wd

Sapphire Cosworth 4wd

Power was delivered to the front and rear wheels from the Ford MT75 gearbox through a Ferguson 4 wheel drive system. The system had two viscous coupling, one on the centre differential and one on the rear differential, the system split power with 34% to the front wheels and 66% to the rear wheels.

The car utilised the same four door Sapphire body shell that was used on the Sapphire RS Cosworth two wheel drive, namely a strengthened four door Sierra Sapphire body. Unlike the three door Sierra RS Cosworth, the styling was very low key the car being fitted with subtle body kit including sill extensions, a front spoiler and a small single vane spoiler mounted on the boot lid. Unlike the Sapphire Cosworth the car did include two bonnet vents that not only improved engine bay cooling but also increase the visual appeal and identified the car from its lesser variants. To keep production costs down the car was offered in a choice of only three colours these being Diamond White, Flint Grey and Metallic Magenta. The car was fitted with unique to the model 15Ē x 7Ē wide lattice alloy wheels fitted with ER90 205/50 ZR15 tyres.

The car used a MacPherson strut arrangement at the front with coil springs and lower track control arms. Monotube telescopic dampers and a thickened 30 mm anti-roll bar was fitted to the front. The rear suspension consisted of semi trailing arms, coil springs with single tube gas dampers, an 18 mm anti-roll bar was fitted also. The spring and damping rates were given the same settings as the 2 wheel drive Sierra Sapphire Cosworth with the emphasis being on improved road holding and refinement. The steering was a traditional rack and pinion affair with hydraulic power assistance needing 2.6 turns lock to lock.

Interior cabin

Interior cabin

The car was fitted with a powerful braking system consisting of 278mm ventilated discs at the front and 273mm solid discs at the rear. Factory fit included a Teves electronic anti lock braking system.

The interior was lifted from the 2.0i Ghia, therefore the car had the benefit of a very well specified interior. Factory fit items included Recaro front sets, a leather trimmed steering wheel and gear knob, central locking, electric front and rear windows, electric mirrors, heated front and rear windscreens and a six speaker stereo system. Optional extras included Air conditioning, on board fuel computer, electronic tilt and slide sun roof and a black full leather interior.

Unfortunately the car never achieved the success that Ford had anticipated within the World Rally Championship due to the weight and overall size of the vehicle. The Sierra Sapphire Cosworth 4x4 was phased out after 1992 and replaced by the smaller Escort RS Cosworth that was built on a shortened version of the same floorpan.

The Facts


Ford Cosworth YBG





Compression Ratio:


Fuel System:

Weber Marelli Fuel Injection

Maximum Power:

224 bhp @ 6,250 rpm.

Maximum Torque:

214lb/ft @ 3,500 rpm.


Ford MT75 - Manual 5 speed.

Top Gear:



Servo Assisted Ventilated Front Discs / Solid Rear Discs

Kerb Weight:

1,302 Kg

Max Speed:

151 Mph


6.5 Secs