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Stuttgart. Three months after the launch of the 911 Carrera ("997" series) Dr. Ing. h.c. F. Porsche AG, Stuttgart, presents the first racing version of the sportscar.
The 2005 911 GT3 Cup is tailor-made for customer motorsport with near-standard vehicles. Porsche delivers the car, which will exclusively run in the Porsche Michelin Supercup 2005 next year, ready-to-race to the customers from March 2005.
With its predecessor - the Cup Carrera based on the "996" series - being a high performance and competitive sportscar which not only competes in the makes cups but has won various Gran Turismo championships, the new model marks a clear step towards a thoroughbred racing car: the GT3 Cup 2005 features a sequential gearbox with a power shift system. The suspension underwent modifications for higher precision and further improved driving dynamics. For the first time Porsche instals its revolutionary Ceramic Composite Brake (PCCB) to a racing car.
The bodywork: downforce improved, weight reduced
High downforce, low weight and the best possible cooling had priority when the classical body silhouette of the 911 was modified for racing.
The adjustable rear wing of the new GT3 Cup gives a clear indication of the purpose of this vehicle. The carbon fibre wing is 60 millimetres wider and 35 millimetres higher than the wing of the 2004 model. It increases downforce at the rear significantly. An intake on the carbon fibre rear lid directs air through a filter directly to the throttle.
The aerodynamically optimized front bumper and front spoiler with two adjustable spoilers in front of the wheel arches increase downforce by up to 40 percent compared to 2004.
Numerous improvements to details optimize the bodywork for motorsport purposes: hot air from the centre front radiator exits the body on the upper side of the front lid. The front brakes are cooled by air from intakes in the spoiler, through air ducts in the wheel arches.
The welded-in safety cage fulfills all FIA requirements. In order to save weight the doors, rear lid, wing and rear bumper are made of carbon fibre composite material. The door windows, as well as the side and rear windows are of plastic. The design and fabrication of all electrical cables specifically for the 911 GT3 Cup contributed to saving further weight. There is only one lightweight racing seat in the cockpit; all sound insulation material was removed.
With all liquids and an empty fuel tank the 911 GT3 Cup 2005 weighs in at around 1,150 kilograms.
The cockpit and dashboard feature a new layout with a central information display which informs the driver about all important functions (revs, temperatures, brake balance, mappings, etc). The light and ignition switches as well as the data recording control are positioned on the centre console with the starter button left of the steering wheel. The fuse-box can now be found in the place of the glove-box instead in the legroom area of the driver's side.
The suspension: realized precision
With a McPherson type front axle and the Porsche multilink rear unit the suspension of the GT3 Cup closely corresponds to the standard suspension.
At the front axle the damper is mounted to the upright with a twin-clamp system. This solution was adapted from the 911 GT3 RSR. With higher stiffness it contributes to increased precision and enhanced driving dynamics through a better response of springs and shock absorbers. The rear axle features RSR uprights as well. The blade-type anti-roll bars front and rear are continuously adjustable as are ride height, camber, and track.
The 2005 911 GT3 Cup is the first works-prepared racing sportscar to feature the Porsche Ceramic Composite Brake (PCCB), a unique development by the German sportscar manufacturer. These cross-drilled, inner-vented composite ceramic brake discs set standards when it comes to response, fading stability, weight and life expectancy. The Cup Carrera features 380 millimetre discs with aluminium six-piston calipers in the front and 350 millimetre discs with aluminium four-piston calipers rear.
The most prominent advantage of PCCB for racing is the reduction of unsprung rotating masses. For the 911 GT3 Cup ca. 20 kilograms are saved compared to steel discs, which further improves the acceleration, agility and traction. Especially for racing with many decelerations from very high speed in short succession it is important that the level of friction remains constant even with very hot brakes under high loads.
As a novelty in Porsche makes cup motorsport the driver can adjust the brake balance from the cockpit. At the same time ABS is no longer available, as the Cup Carreras not only run in the makes cups but are regularly raced in GT championships, where ABS is generally not allowed.
The engine: revs? Yes, please!
The engine is the well-known 3.6-litre six-cylinder boxer that has been the base for successful motorsport with near-standard vehicles for the last six years. It is an extremely free-revving unit that develops 294 kW (400 bhp) at 7,300 revolutions per minute in its 2005-spec: an increase of 10hp compared to last year. Maximum torque has grown to 400 Nm at 6,500 revs per minute. The maximum engine speed is 8,200 rpm. An air-collector located under the rear wing uses pressure built up there to supply extra intake air to the engine at high speeds, so that it reaches its maximum power output even more easily.
The forged pistons, the titanium connecting rods, the valves and valve-train feature lightweight technology in design and materials. With the connecting rods and pistons allowing an improved flow of forces to the crankshaft, the engineers were able to dispense with the usual vibration damper on the crankshaft, saving two kilos in rotating masses further enhancing the free-revving performance of the unit.
The basic engine in sandwich design with the cylinder housing, cylinder head and crankshaft housing combined with one another to form one unit for the three cylinders on each side has a very high torsional stiffness. The cylinder liners featured in the light-alloy cylinder housing are made of aluminium and are coated with Nikasil. The cylinder heads, in turn, are made of an extremely temperature-resistant light alloy.
The dry sump lubrication with a separate oil tank ensures an optimum supply of oil to the engine even under extreme acceleration.
The power train: gear shifting at full throttle
After having gained comprehensive experience with sequential gearboxes in international GT championships Porsche now offers this technology to customers in the makes cups, beginning with the Porsche Michelin Supercup in 2005.
The sequential six-speed dog-type 'box of the latest 911 GT3 Cup features a power shift system with ignition cut for very quick upshifting at full throttle. Very close ratios ensure that the engine is used in its optimum rev range with the transmission being considerably shorter than in the road-going 911 GT3 RS. Top speed is reached at approx. 272kph. Thanks to tailor-made gears, a single mass flywheel and the use of a 5.5 inch triple-disc sintered metal clutch, the rotating masses of the transmission are reduced. An oil-water-heat exchanger provides the reliable cooling of the system.
Technical Description
Porsche 911 GT3 Cup - 2005
Bodywork
- 997-basis
- Self supporting bodyshell made out of galvanised sheet steel
- Carbon fibre rear lid with adjustable rear wing, rear bumper and doors
- Plastic rear-side and rear windows
- Carbon fibre front bumper and front spoiler edge
- Welded-in steel safety cage
- Racing bucket seat, 6-point safety belt suitable for HANS
- Fire extinguisher system
- 64-litre fuel tank
- Air jack
Engine
- Six-cylinder boxer engine
- 3,598 cc, stroke 76.4 mm, bore 100 mm diameter
- Four valves per cylinder
- 400 hp (294 kW) at 7,300 rpm
- Max. torque 400 Nm at 6,500 rpm
- Max. revs 8,200 pm
- Dry-sump lubrication
- Two-stage resonance intake manifold
- Sequential multi-point fuel injection
- Electronic engine management system MS 3.1
- Two catalytic converters, exhaust system with twin-branch centre exhaust tailpipe
- 98 ROZ Super Plus unleaded
Power Train
- Six-speed sequential dog-type gearbox
- Pressure-oil lubrication
- Gearbox cooling with oil-to-water heat exchanger
- Single-mass flywheel
- Hydraulic clutch centre-release mechanism
- 5.5 inch triple-disc sintered-metal clutch
- Limited slip differential 40/60 percent
- Rear wheel drive
Suspension
- Front: McPherson, blade-type anti-roll bar (adjustable), damper mounted to upright with twin-clamp system
- Rear: multilink, rigid suspended subframe, blade-type anti roll bar (adjustable)
- Front and rear: double coil springs; height, camber and track continuously variable adjustable
- Power steering with elctro-hydraulic pressure feed
- Three-piece central locking aluminium rims
- Front axle: 9J x 18, rim offset 43
- Rear axle: 11J x 18, rim offset 30
- Tyres: Michelin
- Front axle: 24/64-18 (slicks, alternative wet)
- Rear axle: 27/68-18 (wet, alternative wet)
Brake system
- Brake system with adjustable bias bar
- Internally ventilated, perforated PCCB brake discs
- Front 380 mm, six-piston alu-callipers, single piece
- rear 350 mm, four-piston alu-callipers, single piece
Weight
- Approx. 1,150 kgs (incl. oil, coolant)
Price
- 121,500 Euros ex-works, plus VAT
Courtesy: Porsche AG. | 
13th September 2004, 14:57
