WRC Technologies
The main distinction of WRC cars from the ring race cars series - is their all-metal body and the close relationship of construction with serial cars. DTM and NASCAR champions' cars at bottom of fact are prototypes that resemble their serial ancestors only outwardly. But WRC regulations strictly confine original car's alterations. Main details of the race car look almost like these details of the common car. Sometimes they are even simpler. And the ginger is that the assemblage and every single detail are perfected.
Perfection above all - are in materials. Light and strong composition materials are used anywhere the regulations allows - even for oil sumps. Wheel bearers are made using ceramics; bracket and transmission details are made of titanium, and wheel disks of magnesium alloy. It only remains to guess what alloys are used for making particularly heavily stressed details like turbomotor piston with charging pressure reaching 2 - 3 bar. The maximum WRC engines power is officially limited - at the most 300 hp. But as the technical committee is unable to control it absolutely precisely the real indexes are 20-30% higher. And this is inspite of the block and flow head being manufactured on the basis of serial details! 34-millimeter air restrictor that is placed on the turbine entrance and restricts quantity of air during high speed doesn't allow driving out the engine. On the other hand the engine torsion torque is just enormous - two litre turbo motors develop to 600 Nm - this figure is bigger than it's in a BMW M6 five titer motor. Another interesting thing is actively applied in the mondial rally - it's the water transmission system into the intake manifold. The water pressure injection through the special nozzle is to 10 bars that decreases the air-fuel mixture temperature almost to atmospheric temperature. This simple as it should seem solution has a striking effect. Temperature conditions of the engine work get better; it becomes less inclined to detonations that allow the charging pressure to be raised higher. But saying the truth the five liter tank of water that is placed behind the driver's seat is enough only for one section - approximately for 60 km. Every leg requires the individual engine settings. For example, before the mountain race charging pressure is raised to compensate the decrease in atmospheric pressure. The 102 gasoline octane rating is provided to all teams one and the same - Shell. Combustion materials are taken away by the exhaust system that is equipped with the safe multi-layer ceramic-aluminum heat insulation. While anti-lag is working, the fuel that rotates the turbine burns down straight in the exhaust system - forks of flame shoot out of the tailpipe and the entire tract makes red-hot. Bleeder pipes are located in such way to not hinder the main car units' servicing.
Change gear is another topic of conversation. Six or five speed gearboxes are used on modern WRC cars. Steps switches with the help of rings and buttons that are placed on the steering wheel hub. To make sure there is a traditional stick shift - for the case of electronics breakdown it can help to carry out an emergency control of the sequential manual gearbox. For switching steps it is needed about 35-50 milliseconds that is in several times faster than on common automobiles.
The gear box is changed on average two times per race on each car. Centre and front differentials are located in the same block with it. Modern WRC automobile gathers speed to 100 km/h in a little over four seconds. But the maximum speed is not impressive - it is around 220 km/h. And it even isn't needed. On special rally sections acceleration and braked dynamics, controllability, running gear's perfection and safety are more important than its maximum speed. Today all teams use simple and serviceable McPherson suspenders. Sometimes for service simplification not only left and right sides details are unified but even front and rear suspensions. On some cars, for example Subaru, the number of shock-absorber external controls comes up to four: it's possible to change the resistance to pressure and rebound on low and high rod speed.
WRC race car's bodies are entirely manufactured from metal, only elements that make aerodynamics better are made of composition materials. As the basis is the body of a serial model, or rather its main elements: body floor, side parts, side columns… And even these details subject to serious revision - for example for placing suspender's and all-wheel-drive transmission's non-standard parts. A safety framework of alloy pipes is connected to the car's body. The overall length of these pipes reaches 50 meters. And the framework becomes a power structure element. It not only protects crew's living space in case of crash but also fastens suspender attachment points together.
Negative aspect of body's and units' strengthening - is car's superfluous weight, with which constructors are always struggling. FIA has even brought in limitations of body's minimum weight - 320 kg with a view to protect pilot's lives. As it's practically impossible to control pure body's weight the technical commission examines car's mass before every stage. According to FIA regulations, every WRC car must weigh no less than 1230 kg. However, throwing the superfluous "fat" off is still lasting. For example many automobiles are equipped with light glass made of polycarbonate. Thanks to such solutions winning kilograms can be used as ballast in certain parts of the car reaching optimal weight distribution that influences over the manoeuvrability and tyre wear. By the way spares, nut runners, lifting jacks and other things that will be useful during the stage can be used as ballast. Therewith, pilot's and navigator's seats are displaced maximize backwards and downward for better balance. Side effects - is miserable field of view from the pilot's seat.
In general, WRC automobiles are much closer to their "civil" relatives than to FIA GT, DTM, NASCAR or race championship cars, not to mention Formula 1. Main engineering solutions are easy and clear, but space technologies hide mainly in used materials.