World Rally Car is a type of racing well known for its incredibly challenging race tracks. WRC specs are introduced by FIA in 1997. Between year 1997 and 2010, there are regulations that constricted that World Rally Cars must be built upon and must look like a current production car of not less than 2500 units. A series of modifications is made such as increasing the engine displacement to up to 2.0L, forced induction with anti lag system( also known as straight pipe systems) conversion of four wheel drive, with sequential gearbox, aerodynamic body modifications, weight reduction such as removing the air conditioning system, removing rear seats and removing audio devices, together with chassis strengthening to acquire greater body rigidity.
Different from previous Group A cars, manufactures are no longer required to build “homologation special” in order to meet approval. Base model does not have to carry the characteristics of the World Rally Car, as seen from cars like the Peugeot 206, 307, Citroen Xsara and Skoda Fabia, which all until this time does not have any road car variant with turbocharged engine or/and four wheel drive. To limit its power, all forced induction WRC rally cars are fitted with 34mm air restrictor before the turbo charger inlet manifold, thus the air flow is limited to approximately 10 cubic meters per minute. This was such due to the intend to limit maximum power output to around 330-340hp. Engine development by WRC competitors does not focus its power on peak power output, instead producing wide power band is their main target. Usually power output in excess of 300hp is made obtainable from 3000 rpm to 7500 rpm maximum, with a peak of 330-340hp at close to 5500rpm. At stage mode idle speed of 2000rpm, the power output is a staggering 200 hp.
Since 2011 however, rules for WRC has changed to become more restrictive. Regulations had derived from the ones for Super 2000 cars, with different engines and aerodynamic kits. Cars are usually smaller models like hot hatches, as the car no longer needs to be minimum of 4m in length. With 1600cc direct injector turbo engine and a smaller 33mm air flow restrictor, and max pressure of no more than 2.5bar absolute, to limit the torque to 400Nm or less. Exotic materials are banned except when they are present in the base model of the car. Carbon fiber and aramid fiber are extremely restricted to only one layer of fabric usable to visible face of the part, except bodywork’s side pretection where multiple layers of aramid fiber are allowed to increase its strongness.
Gear changes must be made with mechanical systems, causes the paddle shifter not being allowed. However in 2015 the paddle shifter is back available. No center differential is available where it used to be 3 differentials, with a 3rd differential included. But new systems only allow mechanical front and rear axle without any sort of hydraulic and electronic controls to reduce cost, minimum weight is 1200kg empty and 1350kg with driver and co-driver and only one spare wheel.
In 2017 turbo restrictor is increased from 33mm to 36mm,and pressure is limited at 2.5bar maximum.it means that hp increase of 80 is seen from the previous 300hp to now 380hp. Minimum weight is also decreased by 25kg.