Audi Sport Quattro: Grandfather of 4WD Rally.

Quattro - A1 and A2 evolutions

The original Audi Quattro competition car debuted in 1980, first as a development car, and then on a formal basis in the 1980 Janner Rally in Austria. Largely based on the bodyshell of the road-going Quattro models (in contrast to the forthcoming Group B cars), the engine of the original competition version produced approximately 300 bhp (224 kW; 304 PS). In 1981, Michèle Mouton became the first female driver ever to win a world championship rally, piloting an Audi Quattro. Over the next three years, Audi would introduce the A1 and A2 evolutions of the Quattro in response to the new Group B rules, raising power from the turbocharged inline 5-cylinder engine to around 350 bhp (261 kW; 355 PS).

The Quattro A1 debuted at the WRC 1983 season opener Monte Carlo Rally, and went on to win the Swedish Rally and the Rally Portugal in the hands of Hannu Mikkola. Driven by Stig Blomqvist, Mikkola and Walter Röhrl, the A2 evolution won a total of eight world rallies; three in 1983 and five in 1984.

 

Sport Quattro

The Audi Sport Quattro S1 was a Quattro programme car developed for homologation for Group B rallying in 1984, and sold as a production car in limited numbers. It featured an all aluminium alloy 2,133 cc (130.2 cu in) (2.1 L) 20v DOHC engine slightly smaller than that of the Audi Quattro (in order to qualify for the 3-litre engine class after the scale factor applied to turbo engines). In road-going form, the engine was capable of producing 225 kW (306 PS; 302 bhp), with the competition cars initially producing around 331 kW (450 PS; 444 bhp).

The vehicle also featured a body shell composed of carbon-kevlar and boasting wider arches, wider wheels (nine inches as compared to the Ur-Quattro's optional 8-inch-wide (200 mm) wheel rim), the steeper windscreen rake of the Audi 80 (requested by the Audi Sport rally team drivers to reduce internal reflections from the dashboard for improved visibility) and, most noticeably, a 320 mm (12.6 in) shorter wheelbase.

In addition to Group B competition in rallying, the Sport Quattro won the 1985 Pikes Peak International Hill Climb with Michèle Mouton in the driving seat, setting a record time in the process. A total of 224 cars of this "short version" Sport Quattro were built, and were offered for sale at a heady price of 203,850 German Marks.

Sport Quattro S1 E2

The Audi Sport Quattro S1 E2 was introduced at the end of 1985 as an update to the Audi Sport Quattro. The car featured an inline 5-cylinder engine that displaced 2,110 cc (128.8 cu in) and produced an officially quoted figure of 350 kW (480 PS; 470 bhp). However, the turbocharger utilised a recirculating air system, with the aim of keeping the turbo spinning at high rpm, when the driver closed the throttle, either to back off during cornering, or on gearshifts. This allowed the engine to resume full power immediately after the resumption of full throttle, reducing turbo lag. The actual power figure was in excess of 500 bhp (373 kW; 507 PS) at 8000 rpm. In addition to the improved power output, an aggressive aerodynamic kit was added that featured very distinctive wings and spoilers to the front and rear of the car to increase downforce. The weight was reduced to just 1,090 kg (2,403 lb), and the S1 could accelerate from 0-100 km/h (62 mph) in just 3.1 seconds. Some of the cars were supplied with a "power-shift gearbox", a forerunner of today's DSG technology.

 

The S1 E2 proved to be an immediate success in the rally circuit, helping Walter Röhrl and Christian Geistdörfer win the 1985 San Remo Rally. A modified version of the E2, was also driven by Michèle Mouton. The S1 evolution would become the final Group B car produced by Audi, with the works team withdrawing from the Championship following the 1986 rally in Portugal.

Twenty-three years after the cancellation of Group B, the Sport Quattro S1 E2 is still widely regarded as the most powerful rally car ever fielded in international competition, with the final factory machines of 1986 rated at 441 kW (600 PS; 591 bhp). In 1987, the car won the Pikes Peak at the hands of Walter Röhrl.

The 2015 Subaru WRX STI

Subaru Rally Team USA (SRT USA) runs an Open Class rally car in the Rally America National Championship with David Higgins piloting the #75 STI.
Beginning with a stock 2014 Subaru Impreza WRX STI right off the showroom floor, the team's technical partner, Vermont SportsCar, modifies the car for competition. First, the vehicle's interior is stripped bare. Then the body shell is lightened and fully seam-welded for added strength.

A multipoint roll cage, manufactured from T45 steel, is welded into place for added stiffness and security.
The standard gas tank is replaced with a rally-proof Kevlar fuel cell and lightweight carbon/Kevlar RECARO SPA ProRacer competition seats — with HANS (Head and Neck Restraint System) — are also fitted to the car. Other interior additions include a custom STI dashboard, carbon fiber door panels, a Coralba C-Giant Rally odometer and an onboard fire suppression system.
 
The stock dampers are swapped out for heavy-duty rally dampers made by Reiger Suspension. The rally dampers are fully adjustable and built to take the abuse that off-road gravel rallying entails. Under the hood sits a 2.0-liter, 4-cylinder, turbocharged and intercooled STI engine with a Rally America Championship-mandated 34 mm turbo inlet restrictor. Launch control, a turbo anti-lag system and a hydraulic handbrake are just a few of the performance modifications.
A Sadev 6-speed, close-ratio dog-engagement gearbox is used, which allows driver David Higgins to shift without depressing the clutch. The DCCD (Driver Controlled Center Differential) is used in a similar way to a stock STI street car, but the team installs a competition ECU for the differential, which allows for greater control of the torque delivery between all four wheels.
The exterior of the car remains close to stock, with the simple addition of mud flaps and a 1/4-inch aluminum skid plate underneath. Up top, a roof-mounted air scoop aids in cooling both drivers inside, 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. No detail goes overlooked on these amazing machines.