Overview: Citroën DS3 R3

Citroën’s new DS3 R3 is aimed at serious rallying privateers, offering off-the-shelf parts to cover hard or loose stages. It’s set to make its rallying debut at the end of 2010.

Designed according to the FIA’s new Group R3T regulations, the DS3 R3 features the same structural design and appearance as the production DS3, with the standard production steel body-shell reinforced by a welded, multi-point roll cage to improve torsional rigidity, shell longevity and safety for the crew.

Motive power comes from a derivative of the familiar turbocharged 1.6-litre PSA-BMW THP engine. Specific racing parts — air box, camshaft, pistons, connecting rods, exhaust and turbo systems, electronic unit and so on — have been deployed to boost the unit’s maximum output to 210PS. Remarkably, this figure is achieved at 4750rpm, making the engine’s resources highly accessible by any standards, even for a turbocharged power-unit. Torque is excellent, with 350Nm available at 3000rpm.

As with the C4 WRC, the six-speed gearbox features semi-automatic sequential control, enabling gear changes to be made more quickly than would be the case with a manual gearbox.

The standard monocoque chassis is lighter than that of the road-going version because it does not have the supports required for the standard car. It is re-welded and fitted with a multi-point tubular steel roll cage. The cage is pre-assembled outside the car to allow for easier and better-quality welding. The monocoque chassis is delivered with all the brackets and mountings required to assemble the car; it does not come ready-made.

In order to improve weight distribution, the battery and automatic fire extinguisher are positioned behind the seats. A steel skidplate protects the underside of the engine. The flexible, FIA-homologated fuel tank remains in its original position.

Running-gear

At the front, the production sub-frame has been altered so that tubular wishbones can be fitted. The axle is both lighter and stronger than on the production model.

The aluminium struts are lubricated in an oil bath, improving the consistency of their operation and extending their lifespan; the lower, frontally-offset anchor point helps increase the travel and the guiding length of the damper.

The DS3 R3 offers a variety of setup options: three track shock absorbers (low and high-speed compression and rebound, adjustable hydraulic bump stop), camber and toe (front and rear), and track width and castor (front).

At the rear, the production cross-member has been reinforced and altered to make it easier to fit the anti-roll bar. The removable rear wheel hubs allow the camber and toe settings to be adjusted independently.

The braking system features a pedal box assembly with two master cylinders. The discs are held in place by four-calliper pistons at the front and two-calliper pistons at the rear. The handbrake is hydraulic.

Engine

The DS3 R3 is Citroën Racing’s first customer-racing product fitted with a turbocharged engine. The 1.6-litre THP engine is very closely related to the production model used by PSA and BMW. Fitted with a regulation-compliant 29mm turbo flange, it develops 210PS and 350Nm on commercially-available fuel.

To mee the FIA’s regulations, many parts have been taken or derived from the production model. For example, the intake and exhaust manifolds, turbocharger, injectors and injection pumps are identical to those used on production models. The air filter, camshaft, pistons, connecting rods and engine flywheel are specific racing parts. To avoid oil surges during long corners and to increase ground clearance, the oil sump has been altered and fitted with a composite partition. The exhaust and turbocharger system is also specific; the catalytic converter is similar to the one used on the C4 WRC. The DS3 R3’s engine ECU also includes a data acquisition system that is able to check a large number of parameters.

Transmission

For the first time, a customer-racing product has been fitted with a semi-automatic gearbox, which reduces the time spent changing gears and increases the unit’s reliability by circumventing driver cock-ups. The electronic management system only authorises gear changes when the engine parameters allow it. The clutch pedal is still present, but is only used to pull away; on the move, the clutch is automatically controlled.

Under the bonnet, the specific elements of the semi-automatic control (solenoid valves, actuators and pressure unit) have all been taken from the production model and adapted to the six-speed gearbox. The housing for the twin-plate clutch has been cast in aluminium, whilst the gearing casing has been cut from the block.

The DS3 R3 made its first outing at the end of August 2009. Initial testing was carried out on rough gravel test tracks, typical of the road surfaces seen in Mediterranean rallies. Development testing continued on tarmac, the ideal surface to test performance, and on flowing gravel roads. In total, DS3 R3 covered over 10,000km in development testing, split evenly among the different types of road surfaces.

Several drivers took part in the tests. They had varying levels of experience, different preferences and driving styles.

Tarmac racing kit (500 parts)

  • Racing engine, assembled and bench-tested, ready to be mounted
  • Gearbox, assembled and bench-tested, ready to be mounted
  • Reinforced body-shell, with roll-cage and seat attachment brackets and accessories — handbrake, ECUs, spare wheel, mounting brackets
  • Reinforced engine sub-frame
  • Protective skidplate for engine and exhaust
  • Adjustable front and rear suspension elements
  • Reinforced hub carriers
  • Adjustable specific front suspension wishbones
  • Maximum size front and rear brake discs
  • Front and rear specific brake callipers
  • Reinforced rear axle
  • Set of rear axle geometry adjustment shims
  • Direct power-steering rack
  • Specific braking system
  • Specific pedal-box assembly
  • Tarmac 7x17" wheels
  • Fuel system with FIA-homologated tank
  • Specific engine and gearbox cooling system
  • High-capacity air exchanger and specific booster circuit
  • Aviation type electrical system with digital instrument panel display
  • Data acquisition system built into the injection unit
  • Roof-mounted air intake
  • Specific wheel arch protections
  • Front and rear tow straps
  • Spare wheel straps

Optional equipment

  • Gravel rallying adaptation kit, including shock absorbers, springs, anti-roll bar, front brake discs, 6x15 gravel wheels and bodywork protective covers
  • Short or long torque settings
  • Co-driver footrest
  • Citroën Racing rear-view mirrors
  • FIA-homologated crash panel doors
  • Xenon headlamp assembly
  • 64MB data acquisition unit upgrade
  • Specific mapping for racing fuel
  • Tool kit, including: wheel hub fitting tool, brake fluid bleed device, steering rack shim
  • Springs of varying levels of stiffness
  • Anti-roll bar of varying diameters
  • Standard bodywork spare parts kit

Equipment not included in the kit

  • Seats
  • Harness
  • Fire extinguishers
  • Battery
  • Spare wheel
  • Jack and tyre-changing accessories
  • Radio equipment and on-board computer
  • FIA-approved anti-shatter protective film
  • Tyres
Citroën DS3 R3
Cylinders 4
Valves 4
Bore/stroke 77.0/85.8
Swept volume 1598cc
PS/rpm 210/4750
Nm/rpm 350/3000
Transmission M6
Driven wheels Front
Running mass * 1230
Mass distribution 64:36
PS/t 170
Nm/t 284
Length 3948
Width 1715
Height N/S
Wheelbase 2465
Track: front
Track: rear
1520
1490
Wheels: tarmac
— gravel
7"x17"
6"x15"
Tyres: tarmac
— gravel
200/50
195/70
Front brakes: tarmac
— gravel
330x30v
300x30v
Rear brakes 300x28
* According to FIA regulations.
v = ventilated.
Text and design copyright Under the Skin 2010. We recommend Firefox.