Citroen C4 WRC set for launch - RallySport Magazine
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Citroen C4 WRC set for launch

The car that replaces the Citroën Xsara WRC will have a near impossible task, with the World Rally Championship version of the Citroën Xsara now destined for a stellar entry motorsport’s history book.
 
The Citroën Xsara WRC has – alone – taken Sébastien Loeb to be the most successful rally driver of all time, a role it fulfilled in a third of the time it took his nearest rival. With Loeb at the helm the Xsara holds the record for the most consecutive WRC wins and it has proven successful in every rally condition, from tarmac, to gravel as well as snow and ice, where it enabled Loeb to break the Scandinavian grip on the Swedish Rally.
 
Its success has even continued after the road car ceased production and the rally car passed into the privateer hands of the Kronos team for 2006, with the latest World Rally Cars struggling to beat the previous season’s Citroën Xsara WRC! Indeed, this year the Xsara WRC has not just been the car to beat, it has been the dominant force in the World Rally Championship, with Citroën heading for another double World title win of manufacturers’ and drivers’ titles for 2007, to go with the manufacturers titles the Xsara won in 2003, 2004 and 2005, along with drivers’ titles for Loeb in 2004 and 2005.
 
The eagerly anticipated replacement is the Citroën C4 WRC, which will appear for the first time in its final form at the Paris International Motor Show on 28 September 2006, after debuting as a the C4 Sport Concept in 2004 as a preview for the Citroën C4 road car.
 
The Sport Concept first turned a wheel in anger in September 2004 and it has then been in development by Citroën since then, preparing for its return to the highest rung of rally motorsport in 2007. Loeb first drove the C4 WRC at Citroën’s test track near Paris in December 2005 and, in between his WRC commitments, has been helping develop the new car.
 
Citroën has also confirmed that Loeb and his co-driver, Daniel Elena, will be sharing the Citroën C4 WRC with Dani Sordo and Mark Marti in the number two car. Sordo is the reigning Junior World Rally Champion, having won the title in a Citroën C2 Super 1600 in 2005 and he has been helping Citroën earn manufacturers’ points in the 2006 after starting the season in a third Citroën Xsara WRC.
 
Remarkably, considering that the World Rally Championship, like nearly all motorsport, is bound up tightly in wide ranging rules, the designers were given a completely free hand to design a vehicle that would symbolize the renewal of Citroën. This was the Citroën C4 Sport Concept, a true exercise in style that met the futuristic vision of a new competition car.
 
Adapting to regulations
Although the overall styling was maintained from the C4 Sport Concept, the car then had to be adapted to international regulations and performance requirements.
 
This is where the design office of Citroën Sport stepped in.  The project working group came up with a first rolling model of the Citroën C4 WRC that was already a long way from the original concept.
 
The roof, for example, was no longer made of glass, since this is banned in rally racing. The front and rear wings, bumpers and spoiler were modified to satisfy regulations and performance criteria. To save time and money, a number of body parts were studied in wind tunnels on a scale of π before validation of the full-size parts at the end of the project.
 
The main lines of the development programme
The role of the development programme was to validate the parts and powertrain sub-systems developed by the design office. Reliability was the first factor and performance the second.  To achieve the desired result, several working sessions were necessary on both asphalt and gravel. The technical team of Citroën Sport then compared the performance of the C4 WRC with that of the Xsara, which remained the benchmark, the absolute reference point.
 
Although it is still in its development phase, the Citroën C4 WRC has shown real potential. Now, its performance can only truly be confirmed in rally conditions.
 
Expectations and objectives
The mechanics, engineers, crews and managers of Citroën Sport, are now impatient to see how the C4 WRC performs in an actual rally event. Designed to be as easy to drive and as reliable as the Xsara WRC, the C4 WRC aims to set even higher standards of efficiency and performance. A car built and developed to enable Citroën to target the "drivers" and "manufacturers" titles once more from 2007.
 
Main technical characteristics of the Citroën C4 WRC
Like the Xsara, its glorious predecessor, the Citroën C4 WRC features four-wheel drive and a 2.0 litre turbocharged engine mated to a transverse-mounted 6-speed gearbox. At 4.20 metes, the C4 WRC is longer than the Xsara and, in line with regulations, therefore has a greater width of 1,800 mm, compared with 1,700 mm for the Xsara. This change should provide better stability on bends.
 
As also laid down in the new regulations, the use of electronic driving aids is limited, in the same way as for the Xsara in its 2006 configuration.  Referring again to the regulatory budget cuts, the sub-systems of the C4 WRC – such as the engines, gearboxes, front, central and rear differentials and dampers – must last longer and be more reliable.
 
Technical characteristics of the Citroën C4 WRC
 
Engine
Turbocharged
Developed from the XU7JP4 engine
Layout: crosswise, tilted 25° towards the exhaust
Number of cylinders: 4 in line
Aluminium block
Capacity (cm3): 1,998
Max power (bhp – rpm): 315 at 5,500
Max torque (mkg – rpm): 58 at 2,750
 
Timing
2 overhead camshafts driven by a toothed belt
4 valves per cylinder
 
Power supply
Magneti-Marelli multipoint injection
Type: 2KR
 
Transmission
4WD
Carbon three disc clutch
Mechanical differentials on the front and rear axles – electronically controlled at the centre
Sequentially controlled 6-speed semi-automatic gearbox
 
Front brakes
Asphalt: ventilated discs, 6-pot callipers
Gravel: ventilated discs, 4-pot callipers
 
Rear brakes
Asphalt and gravel: ventilated discs, 4-pot callipers
Front/rear distribution adjustable by a compensator
Hydraulic handbrake
 
Suspension
Front and rear: MacPherson type with coil spring
Citroën / Exe-TC dampers
 
Steering
Hydraulic power assisted
 
Wheels
Asphalt: 8 x 18 inch
Gravel: 7 x 15 inch
Goodrich Asphalt BF tyres: 225/40-18
Goodrich Gravel BF tyres: 215/65-15
 
Dimensions
Length: 4,274 mm
Width: 1,800 mm
Wheelbase: 2,608 mm
Front/rear track: 1,598 mm
 
Weight
1,230 kg (minimum authorised)

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