2012 Subaru Puma WRX STI RallyCross
The 2012 SUBARU PUMA WRX STI RallyCross car utilizes the 5-door 2012 Subaru WRX STI for team drivers Sverre Isachsen, Dave Mirra and Bucky Lasek.
The team's technical partner, Vermont SportsCar, first begins with a stock Subaru WRX STI right off the showroom floor. The car's interior is then stripped bare and the shell lightened then fully seam welded for added strength. A multipoint roll cage, manufactured from T45 steel, is then welded into place. Fully prepared the dry weight of the car is under 2500lbs, which is approximately 700lbs lighter than a stock STI.
Major differences from the stock STI include the addition of a competition fuel cell, which keeps race fuel contained within a flexible Kevlar bag tank and a lightweight carbon/Kevlar RECARO SPA ProRacer competition seat (w/HANS- Head and Neck Restraint System). Other interior additions include a custom STI dashboard, carbon fiber door panels, and an onboard Fire Suppression System.
One of the biggest differences between the rallycross and stage rally specification cars is the relocation of the radiator to the rear of the car. This is done to protect the radiator from flying debris and impacts typically found in wheel-to-wheel rallycross. Cooling air for the radiator enters through custom carbon fiber ducts on the rear quarters of the cars and exits the rear of the car.
Under the hood sits a 2.0 liter, 4-cylinder, turbocharged and intercooled Boxer engine. Similar to the stage rally car, the rallycross cars feature launch control, a turbo anti-lag system and a hydraulic handbrake. Another major difference between the rallycross and stage rally cars is horsepower. The Global RallyCross Championship requires a 45mm restrictor on the turbo whereas Rally America (stage rally) requires a much smaller 34mm restrictor. The restrictor size difference accounts for an increase of well over 200hp! The rallycross cars produce in excess of 550hp and an impressive 750 lb-ft of torque.
A 5-speed, close-ratio dog-engagement gearbox is used, which allows the team drivers to shift without depressing the clutch. The exterior of the car remains close to stock, with the simple addition of an aluminum skid plate, a roof-mounted carbon fiber air scoop (to aid in cooling the cockpit) and the stock rear wing is replaced with a larger vertically slotted wing, which greatly improves down force to the rear of the car, even as it slides sideways.