In 2003 the Subaru Impreza World Rally Car was given a makeover, replacing the critically-acclaimed ‘bugeye’ shape with the fresh ‘blobeye’, and with it Petter Solberg grasped the World Championship crown. 2002 – Subaru Impreza WRC2002
As with the previous model, the WRC2002 was launched part-way into the 2002 season, on the third round in Corsica. Changes focused on a revised turbocharger housing in accordance with regulations changes, and revised flywheel, exhaust manifold and water injection system.
The net result of the manifold change, contributed to by the new water injection system and turbo housing, was that torque was boosted considerably whilst power stayed capped at the FIA-mandated 300 horsepower.
Once again, work surrounding the water injection system and reservoir was aimed at saving weight, although the 1230kg minimum still applied. Cockpit ventilation was also an area of particular attention, and a revised roof scoop and air ducting were developed. On the dustier events such as Greece, this was so effective it was blanked off to prevent excessive sand and dust entering the car.
Throughout the year general developments (thereby being homologation-free) were made to areas such as the drive shafts, gearbox shift system, and steering column, where the aim was increased rigidity in the latter for improved steering feel.
Due to another change in the regulations, Prodrive reduced the hydraulic pressure in the gearshift mechanism and re-optimised its operation accordingly. The FIA also mandated for the first time that external door mirrors must be mounted on both sides of a car, although this did not affect Subaru due to the similarities of the rally cars to their road-going counterparts.
2003 – Subaru Impreza WRC2003
The 2003 season saw Subaru launch another new-look Impreza, marked by a more visible focus on aerodynamic aspects of the body and a re-styled front end, most identifiable by the change of headlamp shape.
The new car was launched at the beginning of the season in Monte Carlo, and continued the trend of being a four-door saloon, sharing a parallel development programme with its road-going counterpart. It boasted revisions to the engine, roll-cage, body panels and overall aerodynamic package.
With a new turbocharger and improved exhaust manifold, the torque produced by the boxer engine climbed again. Enhanced engine settings were used from Germany in July to improve performance. Sachs dampers were used, and on Rally Sanremo the team experimented with a form of active suspension on Solberg’s car.
Aerodynamics played a big part, and the new rear wing with its carefully sculpted vertical vanes were an example of design details that were evolved and perfected through advanced simulation programmes rather than the traditional method of testing. Continuing the trend, the cockpit buttons and switches had nearly all been moved to a centre console on the WRC2003, providing fewer distractions in the driver’s immediate line of sight.
Prodrive’s technical expertise meant that the car was capable of being fully equipped and rally-ready whilst running below the minimum weight limit. This meant that the lower components were over-engineered to increase weight and strength, thereby putting more weight lower down and reducing the car’s centre of gravity.
A new FIA regulation also mandated that all WRC bodyshells needed to weigh a minimum of 320kg, as a supplement to existing weight limits.
2004 – Subaru Impreza WRC2004
The team started 2004 with last year’s Impreza WRC2003, although sporting a revised ECU, and the new car was launched on Rally Mexico in March. The new variant looked largely the same but, as ever, the changes were concentrated under the skin and in materials used.
The developed ECU used at the start of the season was carried across into the Impreza WRC2004 and was coupled with revised engine internals and a modified cooling system. As anticipated, the average temperature of rallies during the season was higher than previously experienced, so the radiator and intercooler were reclined at the front end of the car to maximise airflow and cooling efficiency.
In a period in which the technical regulations were changing quite rapidly, the team made the most of development opportunities within the rules, but the car was inevitably an interim design solution at a time of turbulence and uncertainty. Until rules became clear, the WRC was in a relative state of flux.
Taking advantage of the bodyshell weight ruling from the previous year, the team fitted lightweight body panels and polycarbonate windows to reduce the shell close to the 320kg minimum. This also allowed them to shed weight from high up on the car and add ballast low down, always working towards lowering the centre of gravity.
Following the early use of water-cooled front brake calipers, the team fitted Solberg’s car with a total-loss water spray system which reduced the temperature of the front brakes by spraying the discs.
another great article from HSPN.