Audi S1 EKS RX quattro: A small but powerful performer

In the planning stage of the rallycross project in 2014, the S1 became the car of choice relatively soon. According to team principal Ekström, the subcompact car with its short wheelbase and minimal overhang is perfectly suited for the sometimes very narrow rallycross circuits. Thanks to its good traction and sophisticated suspension, it is in contention for victory on both fast and slow tracks. Aside from these factors, the start is particularly crucial in rallycross. This is when up to six cars are pitted against each other. After the start, the narrow circuits offer only limited overtaking opportunities. 

For the 2018 season EKS Audi Sport has prepared two all-new Audi S1 EKS RX quattro cars. Previously, the team had decided that the first four prototypes no longer satisfied the requirements profile for tackling the battle for the drivers’ and teams’ world championships. With respective technical and aerodynamic innovations the squad aims to outstrip the competition around Volkswagen and Peugeot again. 

Under the hood of the Audi S1 EKS RX quattro, a two-liter turbo engine provides the required power. The transverse inline-four unit delivers 580 hp (426 kW) and develops more than 700 Nm of torque which, in spite of its 45-mm air restrictor, makes this engine a similar brute as the one used in the old Group B monster from the 1980s, although the vehicle’s weight is only 1.3 metric tons – including the driver. Hardly of any consequence in terms of weight is the fuel tank with a capacity of 20 liters – which is enough for the short racing distances.

Gears are mechanically shifted using a sequential six-speed transmission. Thanks to the unit’s short gear ratio combined with its extreme ability to transmit power to the wheels and thanks to systematic lightweight design, with many parts of the body kit consisting of carbon fiber reinforced plastics, the all-wheel-drive rocket catapults the driver from 0 to 100 km/h in 2.5 seconds. Not even Formula 1 cars accomplish this in less time. By contrast, the Audi S1 EKS RX quattro achieves a relatively low top speed of 210 km/h which is enough, though, on the World RX tracks with their short acceleration sections and straights covering a maximum of a few hundred meters.

As far as its exterior is concerned, the subcompact car from Ingolstadt features aerodynamic modifications. Large wheel arch cutouts and flared fenders catch the eye. In addition, a roll cage and massive rear wing transform the fast city car into a rallycross monster bursting with vigor. The large air scoops in the rear side windows and the roof supplying the radiator installed at the rear end with fresh air are a special characteristic. There is a good reason for this unusual arrangement. If the radiator sat at the front, gravel and mud might obstruct air supply and possibly cause the engine to overheat. 

For the car’s exterior design, Ekström and his team deliberately integrated elements of the legendary Audi S1 quattro from the 1980s. As a result, the fenders of the Audi S1 EKS RX quattro are “slightly sharper and more angular than those of the other rallycross cars,” according to Ekström. However, the regulations are very strict in this respect. The width of the racing version may differ from the road-going car by a maximum of seven centimeters. In terms of length, the dimensions even have to be exactly identical.

Also special to rallycross are the specification tires supplied by U.S. manufacturer Cooper Tires. “We have a cut slick that’s very soft. In other series, you’d call it a qualifier,” says Ekström. Only eight of these tires are available to each driver on a weekend with up to six races. “Due to the soft compound and the hand-cut tread, it’s possible to drive on gravel rallycross tracks nearly as fast as on tarmac,” Ekström emphasizes.

In order to lose as little time as possible even in cornering the Audi S1 EKS RX quattro cockpit includes a special eye-catcher. Unlike its production counterpart, the rallycross race car has an oversized handbrake projecting upward at a steep angle and is directly installed next to the gear knob. When used, the handbrake decouples the rear wheels from the drivetrain, causing them to break traction and slide out. This makes it possible to perform drifts through the tightest turns.