The Manthey Racing team from Germany will run two brand new Porsche 911 GT3 RSR race cars in the 24 hour race at Spa in Belgium on 29 July. Porsche developed the near-standard racing sportscar
based on the road-going 911 GT3 RS, and put it in the hands of the experienced team under the direction of team principal Olaf Manthey. Works drivers Timo Bernhard and Marc Lieb (both from Germany) share driving duties with Pedro Lamy from Portugal in the GT3 RSR with starting number ‘111’. Driving the Porsche with starting number ‘197’ are further ‘works’ drivers Lucas Luhr (Monaco), Sascha Maassen (Belgium) with Marcel Tiemann (Monaco).
For Porsche and Manthey Racing the race is regarded as an important test under race conditions and at the same time serves as an assessment of the vehicle’s development. For 2006, this race is the only event that is currently planned. For Spa, the car is entered in the so-called Group 2 category where vehicles from national championships are eligible to compete. In 2007, the 911 GT3 RSR will be available for customer’s to race and aims to replicate the success of its predecessors. Porsche customer teams claimed class wins at Spa every year since the GT3 first competed there in 2001 – with an overall victory in 2003.
In the FIA GT Championship, the American Le Mans Series and the Le Man Series as well as at the endurance classics of Le Mans, Daytona, Sebring and the Nürburgring, the GT3 in its various versions secured many records and title wins.
Built on the 911 GT3 RS, a particularly light and sporty derivative of the 911 GT3, the current GT3 RSR is designed to comply with the A.C.O (Automobile Club de l’Ouest), the FIA-GT and IMSA (International Motorsports Association) as well as VLN (Veedol Langstrecke Nürburgring) regulations. Porsche decided to build the new GT3 RSR after analysing the relevant A.C.O. and FIA regulations in a specification which allows a minimum weight of 1,225kg (predecessor: 1,125kg) and permits the tyre width to be increased by two inches to 14 inches. Thirty-five kilogrammes of the required additional weight may be placed as ballast in the vehicle, resulting in a lower centre of gravity.
For the normally-aspirated Porsche engine this specification allows a capacity of 3.8-litres with two 30.3 millimetre air restrictors (predecessor: 3.6-litres, 29 mm diameter). The increase in displacement was achieved through the enlargement of the bore to 102.7mm with the unchanged stroke of 76.4mm. With the mandatory air restrictors, the unit delivers 359kW/485bhp at 8,500rpm. Maximum torque increased to 435Nm. Top engine speed is reached at 9,000rpm. Thanks to the increase in capacity and the corresponding reprogramming of the electronics the top performance as well as the response and driveability have further improved. The new positioning of the mid-front radiator and the use of side radiators – taken from the high performance Carrera GT sportscar – contribute to the thermal health of the engine.
For the 24 hour race in Spa, the GT3 RSR features the proven sequential six-speed gearbox of its forerunner. The customer vehicles for 2007 will be delivered with a new sequential six-speed transmission featuring the gears of the RS Spyder which competes in the American Le Mans Series.
The bodyshell of the GT3 RSR with the welded-in safety cage is ten per cent stiffer than its predecessor. Distinctive wheel arches widen the body by 50 millimetres on each side. The track is enlarged correspondingly; wheels and tyres of the maximum allowable dimension can be fitted.
The relocation of the supplementary oil tank (option), the power steering and the battery to the front improve the weight distribution. The front and rear lids, the front mudguards, the wider rear, the doors as well as the front and rear panelling and wing consist of carbon-fibre composite material. The rear and side windows are manufactured from light polycarbonate.
The newly-developed aerodynamic package improves the air flow efficiency compared to the forerunner (‘Type 996’ GT3 RSR) by a total of around seven per cent. Air flow to and from the radiators, the brakes and the engine are further optimised. In compliance with the FIA and A.C.O. regulations, the new GT3 RSR features a flat underbody.
The suspension with Porsche-optimised struts at the front and the Porsche multi-link axle at the rear corresponds to the configuration of the standard GT3 RS car. The modified kinematics is set-up for the wider tyre footprint and for the lowest possible camber change in rebound and compression. The new ZF-Sachs shock absorbers feature the Through-Rod-System with considerably lower chamber pressure and hence less friction than conventional dampers. As a result they offer a significantly improved response characteristic. The position of the rear axle was optimised. The axle features a new anti-roll bar, an adjustable upper link and an optimised lower link.
The brake system features six-piston aluminium callipers and 35 millimetre thick brake discs measuring 380 mm in diameter at the front and 30 millimetre four-piston aluminium callipers with 355 mm diameter discs at the rear.
Over the 2006/07 winter, 35 units of the new racing sportscar (not approved for road use) will initially be built.