PORSCHE 911 CARRERA 2.8 RSR

Cette collection est une adaptation de Porsche Racing collection - Éditeur : Centauria Editore s.r.l.

A SINGLE MOTTO : REDUCE WEIGHT AND GET MORE HORSEPOWER FROM THE ENGINE

To transform the 911 Carrera 2.7 RS Coupé into the 2.8 RSR, Porsche engineers focused primarily on weight reduction, achieved by reducing the thickness of the steel sheets that were not essential to the rigidity of the body, as well as that of the window glass. They also worked on other points, such as adopting lighter plastic seats, eliminating the soundproofing panels and the rear seat, and installing a 36-amp-hour battery instead of 66.

As a result, the weight dropped from 1,075 kg for the road-approved 2.7 RS to around 840 kg for the RSR Group 4. Since the technical regulations allowed the engine capacity to be modified by increasing the bore, the engine size was increased from 2687 to 2806 cm3 . The crankcase and connecting rods and cranks assembly remained unchanged, but the cam profile was altered to make it more suitable for use on the track. The boxer's cylinder heads were equipped with dual ignition, with two spark plugs per cylinder.

MORE HORSEPOWER WITH THE 3-LITRE

With the compression ratio increased from 8.5:1 to 10.3:1, power output jumped from 210 bhp at 6,300 rpm to 300 bhp at 8,000 rpm, and an additional oil cooler helped the engine withstand higher stress levels. The gearbox's housing, made from magnesium alloy, met the requirements of the RSR, so different gear sets were simply made to allow the gears to be changed to suit the various types of circuits, while gear cooling was improved by the use of geared oil jets. The control of the mechanical limited-slip differential with friction washers was increased to 80%.

("THE SUSPENSIONS ARE SIMILAR TO THOSE OF THE 2.7 RS COUPE")

The geometry of the suspension system was virtually identical to that of the 2.7 RS. However, the front suspension received additional springs and larger-diameter stabilising torsion bars, while the various links between the rear arms and the body were provided by joints offering greater rigidity for improved wheel control.

The six-cylinder boxer engine of the Carrera 2.8 RSR. With a slight increase in the compression ratio and cubic capacity compared to the engine fitted to the 2.7 RS, power increased from 210 to 300 bhp. New cam profiles provided power and torque curves that were more suitable for the race track.

THE BRAKES DERIVED FROM THE 917

The braking system was revised based on experience acquired in endurance racing with the 917, fitting large axially and radially perforated discs and a four-piston wing caliper manufactured by Porsche. Brake distribution between the front and rear axles was adjustable by the driver, and was progressively controlled by a lever in the passenger compartment. The wheels, forged and manufactured by Otto Fuchs, remained 15 inches, but the competition tyres were 230/600 at the front and 260/600 at the rear. After a brilliant 1973, further changes were made to the RSR for the following season.

The engine size was increased to 2,994 cm3 by enlarging the bore, and power was increased to 330 bhp. But that was not all: Porsche, having accumulated considerable experience and expertise in the area of turbocharging, prepared a few units of the 911 Carrera RSR Turbo in 1974. But in this case, to comply with the regulations, the cubic capacity was reduced to 2,142 cm3 by modifying the bore and stroke. Power was nevertheless increased to 500 bhp.

A stripped-down RSR cabin with no superfluous noise-reducing materials. Plastic-shell seats were made lighter, the side windows thinner or made of Perspex, and the battery smaller. The result was a saving of 220kg in weight, giving the car a truly exceptional power-to-weight ratio. © IXO Collections SAS - Tous droits réservés.

STAGGERING PRICES

While the RSR badge adorning all Porsche 911s is an object of great envy, it is only available to the world's wealthiest individuals. Very few authentic cars from 1973 have survived. One of them is on display at the Porsche Museum in Zuffenhausen. A 911 Carrera RSR 2.8 in perfect condition was auctioned at RM Sotheby's in October 2018 for $2.4 million. In 2021, the same auction house offered a 911 RSR 3.0 used in 1974 by two-time world champion Emerson Fittipaldi in the International Race of Champions (IROC) for $1.8m. However, the car failed to find a buyer because of its bad reputation: one of its previous owners was the bloodthirsty drug baron Pablo Escobar.

DATASHEET - PORSCHE 911 CARRERA RSR

ENGINE 6 cylinders, boxer, rear
CYLINDER capacity 2,806 cm 3
POWER 300/310 bhp at 8,000 rpm
TORQUE 291.5 Nm at 6,300 rpm
DISTRIBUTION 1 OHV per bank, 2 valves per cylinder
POWER Mechanical injection
GEARBOX 5 gears
MAXIMUM SPEED 286 km/h
ACCELERATION 0-100 5"6
CHASSIS monocoque
FRONT SUSPENSION McPherson
REAR SUSPENSION Longitudinal arms
BRAKES ventilated and perforated discs
FRONT / REAR WHEELS 15"/15"
BODYWORK steel and fibreglass/resin
LENGTH 4,128 mm
WIDTH 1,651 mm
HEIGHT 1,321 mm
WHEELBASE 2 271 mm
FRONT WHEEL 1 402 mm
REAR WHEEL 1 422 mm
WEIGHT (EMPTY) 840 kg
Since the data concerning this car has never been officially published, the characteristics indicated here have been taken from the most reliable documentary sources.