Ford Sierra Sapphire Cosworth 4WD
Ford Sierra Sapphire Cosworth 2WD
The car was conceived in 1983 before the RS1700T
project was completed. Hence
the RS200 engine was based on this RS1700T development
unit. Between 1983 and
85 the car was designed and built to conform
to Group B rally requirements.
The Engine
The engine was a 1.8 litre 16 valve DOHC turbocharged
unit which was installed
longitudinally at the rear of the car. The Cosworth
BDT block used 86mm bore with
a traditional 77.62mm stoke, displacing 1803cc.
The engine block was based on the
RS1700T with modifications, including using a
dry sump design and improved water
and fuel pumps. A stainless steel four-into-one
exhaust was used.
As per usual this Ford/Cosworth vehicle used a
Garrett supplied turbocharger. This
turbo was a hybrid TO3/4 unit and used a boost
pressure of 1.2bar/17psi for the
rally supplied vehicle. With a lowered engine
compression ratio of 7.8:1 this gave a
quoted power output of 380 bhp, an amazing 211
bhp per litre!.
Gearbox and Transmission
The transmission system used three Ferguson-patented
LSD (Limited Slip
Differential) viscous couplings to power the
four wheels. One fitted next to the engine
gear box the other two mounted at the centre
of each axle. This set-up was designed
to give the RS200 a 37% front and 63% rear power
split. Also the centre differential
could be locked to give a 50/50 front/rear power
split for very slippery surfaces. This
lock was activated via a manual lever inside
the cockpit and only available for the
rally supplied vehicle.
The power was supplied to 16inch alloy wheels
which were shod with some of the
earliest manufactured Pirelli P700 225/50 VR
16 tyres.
Suspension and Brakes
The brakes were AP ventilated 285mm discs all
round using four-piston alloy
calipers. These brakes were powerful enough not
to need power assistance.
The suspension used wide wishbones with twin dampers
and the provision for twin
coil springs. Although production vehicles only
used one coiled spring per wheel.
The manual steering was conventional rack and
pinion system using modified Sierra
components.
Body Work and Interior
The RS200 was produced in both LHD (Left Hand
Drive) and RHD (Right Hand
Drive) format.
The original vehicle shell design was by Ghia
in Italy, working closely with the
Boreham based Ford motorsport design team.
The shell was a one off design and was not based
on any production Ford vehicle.
The chassis was a tubular space frame design
with a light weight fibreglass body. The
roof panel and upper door openings were fabricated
in a composite glass, carbon
and aramid fibre mix. Perspex was used for the
side and rear windows for its
lightness.
Sierra doors and windscreen were originally used,
although the doors were later
made also in fibre for the production models.
The twin aluminium petrol tanks were mounted behind the seats.
Six prototype models were developed with the remaining
194 prodution cars being
built at Reliant in their Shonstone factory.
Yes the same company famous for its three
wheel fibreglass car used by Dell Boy and Rodney
Trotter.
The car was supplied in two forms:
A Rally ready form
A Road going form
The road car featured Sparco seats in red or black,
with a leather trimmed XR3i
steering wheel. The road car also had fitted
carpets and door inserts. The road tamed
version also used a less powerful engine to improve
longevity.
The RS200 was only ever produced in white with blue decals.
Vehicles of such high power and speed were later
banned from Group B for 1987,
after a number of spectator accidents on the
Irish and Corsican rallies. For 1987 the
World Series would be devoted to Group A cars
of which at least 5000 per year had
to be produced. This meant Ford devoted its rally
attentions to the Sierra 3 door
Cosworth and Sierra XR4x4. Hence we saw the death
of the RS200 and its
competitors, Austin Rovers 6R4, Peugeot T16,
Lancia 037 and Lancia Delta S4.
The original RS200 had a list price of 49950 Sterling,
with various extra options
available from Ford. This RS200 remains today
one of the rarest modern RS
marques along with the Sierra 3 door RS500 Cosworth.
Due to its rarity, no up to
date pricing information is available.
The vehicle was available from 1990 in both RHD
(Right Hand Drive) for the UK
market, and LHD (Left Hand Drive) for Europe.
The Engine
As per the Sierra Sapphire 2WD Cosworth with the following differences:
A Cosworth revised head and stronger cylinder
block to prevent head gasket failure
which affected the earlier Sierra 3 door Cosworth,
and Sierra Sapphire 2WD
Cosworth.
The revised head featured an improved combustion
chamber design and was sturdier
around the exhaust valves, where head gasket
failure was likely to occur.
An improved cast iron exhaust manifold was used
to reduce vibration and the chance
of stress induced cracks.
This 4WD Cosworth model's intercooler was enlarged
by 25% to further aid cooling.
Higher engine output power had to be achieved
to overcome the restriction of the
catalytic converter.
Although engine power output was improved over
the 2WD model, any speed gain
was lost due to front wheel transmission loses.
Output power was claimed as 224
bhp at 6000 rpm.
The engine was converted to run on Unleaded Fuel
and this Unleaded unit used a
catalytic converter on the exhaust system. This
restricted the exhaust system flow
considerably.
Red coloured engines indicate a 4 Star petrol
unit and green an Unleaded Petrol only
version.
Gearbox and Transmission
The main area of modification over the 2WD model
was obviously due to powering
the front wheels. Hence the transmission was
a complete new design with drive rods
to the front two wheels. A mechanical Anti-Lock
Braking System (ABS) was also
employed on this new 4WD model.
Body Work and Interior
As per the Sierra Sapphire 2WD Cosworth with the following differences:
Different style bonnet
vents.
New style alloy wheels
with locking hub caps.
Driving lamps mounted
within the front spoiler.
Available colours where:
White
Graphite Grey
Metallic Magenta
Smokestone Blue
Optional extras where:
Black leather interior
Air Conditioning
On board fuel computer
Electric tilt and slide
sun roof.
The Sierra Sapphire 4WD was produced until 1993,
when sadly the Sapphire was
discontinued to make way for Fords new rep-mobile
the Mondeo (yawn, yawn!).
Although Ford's alliance with Cosworth continued
in the form of the MK5 Escort RS
Cosworth.
UK price guide (Sterling)
Condition Excellent Good Average
Sterling 10000 9000 8000
Note: The FORD Sierra Sapphire Cosworth 4WD was
produced on H to
K-registration plates in the UK.
For further details see Vehicle Registration Plate Guide.
NOTE: For turbo longevity it is recommended that
the Sierra Cosworth along with all
other turbocharged RS models run with fully synthetic
oil. These types of oil give the
necessary engine protection for the high temperatures
attained in turbocharged
vehicles.
The Sierra Sapphire Cosworth was based on the
Sierra Sapphire of the time. Further
details of which can be found in the Ford Sierra
1982 Workshop manual.
The vehicle was available in both RHD (Right Hand
Drive) for the UK market, and
LHD (Left Hand Drive) for Europe.
The Engine
The Cosworth engine was based on the Sierra 3 door Cosworth unit.
The Cosworth engine was coloured red to indicate
it could be run on Four Star
leaded petrol.
Gearbox and Transmission Suspension and Chassis Body Work and Interior
Some complaints were heard on the release of this
new shape Sapphire Cosworth
that the dashboard was particularly bland. For
such a high performance engine only
minimum instrumentation was fitted.
Front Recaro bucket seats, with adjustable head restraints were used.
Tilt and Slide FFSR (Factory Fitted Sun Roof),
Electric windows and mirrors,
Central Locking, and Tinted Glass, were all standard
equipment.
Available colours where:
White
Graphite Grey
The Sierra Sapphire Cosworth had colour coded
front spoiler, side skirts and rear
boot mounted spoiler.
The Sierra Sapphire 2WD was produced until 1990,
when the new 4 wheel drive
Sierra Sapphire 4WD Cosworth replaced it.
UK price guide (Sterling)
Condition Excellent Good Average
Sterling
9000 7500 6000
Note: The FORD Sierra Sapphire Cosworth 2WD was
produced on E to
H-registration plates in the UK.
For further details see Vehicle Registration Plate Guide.
NOTE: For turbo longevity it is recommended that
the Sierra Cosworth along with all
other turbocharged RS models run with fully synthetic
oil. These types of oil give the
necessary engine protection for the high temperatures
attained in turbocharged
vehicles.
The Sierra Sapphire Cosworth was based on the
Sierra Sapphire of the time. Further
details of which can be found in the Ford Sierra
1982 Workshop manual.
Available colours where:
White
Graphite Grey
The Sierra Sapphire Cosworth had colour coded
front spoiler, side skirts and rear
boot mounted spoiler.
The Sierra Sapphire 2WD was produced until 1990,
when the new 4 wheel drive
Sierra Sapphire 4WD Cosworth replaced it.
UK price guide (Sterling)
Condition Excellent Good Average
Sterling
9000 7500 6000
Note: The FORD Sierra Sapphire Cosworth 2WD was
produced on E to
H-registration plates in the UK.
For further details see Vehicle Registration Plate Guide.
NOTE: For turbo longevity it is recommended that
the Sierra Cosworth along with all
other turbocharged RS models run with fully synthetic
oil. These types of oil give the
necessary engine protection for the high temperatures
attained in turbocharged
vehicles.
The Sierra Sapphire Cosworth was based on the
Sierra Sapphire of the time. Further
details of which can be found in the Ford Sierra
1982 Workshop manual.
The Sierra Cosworth RS500 a much uprated version
of the production Sierra 3 door
Cosworth. Only 500 of these special vehicles
were produced, all modified by
Tickford. This Cosworth was announced in July
1987 and was homolgomated in
August 1987.
The RS500 was only available in RHD (Right Hand
Drive), althought some of these
may have found owners on mainland Europe.
The Engine
The main difference to the Sierra 3 door Cosworth
was the uprated Cosworth
competition engine. It's new features were:
The engine had a thick
walled cylinder block to cope with the rigours of the
track.
A larger turbocharger
and intercooler was fitted.
To the fuel system a
second set of injectors was added and uprated fuel pump.
The oil and cooling
system were both also uprated.
A genuine RS500 Cosworth engine should be labelled
in the range YBD0015 to
YBD0537 .
Suspension and Chassis
Genuine RS500 shells were labelled GBBE GG 38600
to GBBE GG 39099 .
These chassis labels are found under a small
flap next to the drivers seat and also
mounted in the engine bay. Both should display
the same numbers.
Body Work and Interior
The RS500 had only minor external cosmetic differences
to its parent the Sierra 3
door Cosworth:
The rear tail gate also
had a lower spolier in additional to the upper whale tail.
This Cosworth had discrete
RS500 badges on the rear tail gate and front
wings.
Re-designed front bumper
and spoiler to aid cooling and air flow.
The bonnet louvre air
vents were also of a slightly different design.
Available colours where, (with production figures in brackets):
Black (392)
White (52 plus 4 Ford
prototypes)
Moonstone Blue (52)
UK price guide (Sterling)
Note the RS500 is a rare vehicle and hence the
prices reflect this. Potential buyers
would be lucky to find one available for less
than 15000 Sterling! This Cosworth
remains today one of the most sought after modern
RS marques.
Condition Excellent Good Average
Sterling
15000 Not Applicable
Note: The FORD Sierra Cosworth RS500 3-door was
produced on D and
E-registration plates in the UK.
For further details see Vehicle Registration Plate Guide.
NOTE: For turbo longevity it is recommended that
the Sierra Cosworth RS500 along
with all other turbocharged RS models run with
fully synthetic oil. These types of oil
give the necessary engine protection for the
high temperatures attained in
turbocharged vehicles.
1985 10
1986 1064
1987 579
Total: 1653
Many of these cars were used very successfully
for racing, in both rally and road
events:
The Engine
Development of the Cosworth engine was started
way back in 1982 on a non-turbo,
16-valve, Dual Over Head Cam (DOHC) version.
This version was coded YAA.
Ford planned to use this engine, but TURBOcharged
it!
This turbo version became the first Ford Cosworth
engine and was coded YBB
(nothing like a logical naming convention). The
first production began in 1987 after
further development of the engine by Cosworth.
The first engines to be used by
Cosworth in the two wheel rear drive (3 door)
Sierra was coded YBD and had a
measured output of 204 bhp at 6000 rpm. Peak
torque was 203 lbs ft at 4000 rpm.
No diesels here!
The engine specifications were:
Displacement:
1993 cc
Bore:
90.8 mm
Stroke:
77 mm
Compression Ratio:
8.0:1 with pentroof combustion chambers
Inlet Valves
35mm operated via bucket tappets
Exhaust Valves
31mm (sodium cooled) operated via bucket tappets
Cam shafts
Running five bearings
Turbocharger:
Garrett AirResearch TO3
unit with integral waste gate and water cooled
centre-housing. As originally
fitted to the MK3 Escort Series 1 Turbo.
Turbo boost pressure:
9 psi
Injection and Ignition system:
Weber-Marelli multi-point
fuel injection
Oil Cooler
Water to oil intercooler
mounted on the side of the block
Both crankshaft and conrods were heat-treated
steel items to add further strength to
the engine.
The turbocharger also used a dump valve which
let the turbo keep spinning when the
throttle was released. Thus improving the engines
response times. The TO3 turbo
was mounted on top of the high nickel content
exhaust manifold. A special mounting
plate was used to allow the turbo to grow as
it got hotter without cracking or causing
undue stress.
The compressed air exiting the turbo was feed
to an air-to-air intercooler mounted
next to the engine coolant radiator.
Cosworth chose belt drive for the twin overhead
cam engine. These Uniroyal rubber
reinforced fibreglass items were used to power
the oil pump and distributor.
The engine also used a high pressure oil pump
needed to feed the spray jets, which
pointed underneath the Mahle forged piston crowns.
(The engine and turbo system had great tuning
potential as detailed in the MK4
Escort Series 2 Turbo page.)
The engine was coloured red to indicate it could be run on Four Star leaded petrol.
This took the Ford Sierra from being a boring
rep-mobile into a fire breathing road
rocket. This set Cosworth and Ford on a ten year
path together producing one of the
best affordable super cars.
Variations of this successful engine were subsequently used in the:
Sierra 3 door RS500 Cosworth
Sierra Sapphire 2WD
Cosworth
Sierra Sapphire 4WD
Cosworth
MK5 Escort RS Cosworth
The Management Engine System
This Cosworth engine, like its turbocharged stable
mate the MK3 Escort Series 1
Turbo, used a sophisticated engine management
system. This system controlled:
Ignition timing
Fuel injection
Fuel pressure
Turbo boost pressure
Gearbox and Transmission
The Sierra Cosworth used a five speed manual gearbox
mounted at the rear of the
engine. This fed the prop shaft which then fed
power via the rear differential to the
back wheels. The gearbox was a Borg-Warner T5
5-speed unit taken from the 2.3
Turbo Mustang with a modified 5 gear ratio. The
rear differential was a
Ferguson-type 7.5 inch viscous unit.
The 11.1 inch brake front disks were 0.94 inches
thick and used Ferodo F3432
pads.
Suspension and Chassis
Steering was non power-assisted and used a rack
and pinion. Front suspension was
via independent MacPherson struts with anti-roll
bar. Dampers were gas filled twin
tube units from Fichtel and Sachs, the preferred
supplier to the Ford SVE group for
all Ford Cosworths.
The rear suspension used much of the Sierra XR4
4WD layout. It used trailing rear
arms with uniball joints and again Fichtel and
Sachs gas filled damper units.
Body Work and Interior
With the Sierra's huge whale tail this car could
not be described as a street sleeper by
any stretch of the imagination. Much design had
gone into this rear fin to produce a
large down force. The down force was measured
at 164 Nm (124 mph wind tunnel
test) compared with the standard 3 door Sierra's
of 513 Nm UPLIFT!
Available colours where:
Black
White
Moonstone Blue
BBS style Rial manufactured alloy wheels sported
the new Dunlop D40 205/50 x 15
VR low profile tyres.
This Sierra Cosworth featured colour coded bumpers,
side skirts and mirrors.
Driving lamps mounted within the front spoiler
came as standard.
In 1987 a limited edition uprated version of this
Sierra Cosworth was produced, it
was named the RS500 since only 500 were produced.
The Sierra Cosworth 3 door was produced from 1986
to 1988, when the Sierra
Sapphire 2WD Cosworth based on the new design
Sapphire 5 door shell replaced it.
UK price guide (Sterling)
Condition Excellent Good Average
Sterling 11000 9000 7500
Note: The FORD Sierra Cosworth 3-door was produced
on C to E-registration
plates in the UK.
For further details see Vehicle Registration Plate Guide.
NOTE: For turbo longevity it is recommended that
the Sierra Cosworth along with all
other turbocharged RS models run with fully synthetic
oil. These types of oil give the
necessary engine protection for the high temperatures
attained in turbocharged
vehicles.
The Sierra Cosworth was based on the Sierra of
the time. Further details of which
can be found in the Ford Sierra 1982 Workshop
manual.