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| Dream Cars & Bikes - Porsche Carrera GT
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After two years, the Carrera GT Concept first seen at the 2001 Paris Auto Salon is finalized by its production counterpart. Released at the 2003 Geneva Auto Show, the Carrera GT represents Porsche's first limited production supercar since the 959 and one of the few available products that rival the Ferrari Enzo.
Motivation for the Carrera GT came from Porsche's successful motor sports program. A decision to start the Carrera GT as a proposal for Le Mans came after the last Porsche victory there in 1998 . The new car would homage to cars including the 917 and GT1. Both these cars have won Le Mans and both lent their technical developments to the Carrera GT.
Unlike the 911, which has carried the company for four decades, the Carrera GT has a new style and substance. Its styling, thankfully unchanged from Paris show car, departs from the traditional Porsche design language which the 959 couldn't escape.
Under the skin, the car uses familiar hallmarks of motor sport. combining light weight design and a low-centre of gravity with a mid-mounted engine. Having a mid-mounted engine helps the Carrera GT achieve better undertray airflow not possible on the rear-engine 911. If one aspect of the Carrera GT was to filter down to the 911, it could be this mid-ship layout.
A new V10
Powering the Carrera GT is 68-Degree V10 originally intended for Le Mans. It has been modified by Porsche engineers to ensure more power and reliability. Such revisions include a larger displacement offers more torque and more driveability.
This engine is placed mid-ship in the chassis within a three-point carbon subframe. This is unlike Paris Show Car which featured its V10 as a load bearing structure within the chassis. Had Porsche not used a subframe, the noise leakage would have hampered comfort.
The intake system is equipped with Porsche's VarioCam technology found on the current 996 range. VarioCam continuously adjusts the angle of the intake camshaft to optimize performance and output.
Making the engine as light as possible was a primary goal. A light alloy crankcase and titanium connecting rods help the engine have a weight of 452 lbs (205 kg). Compare this to the Enzo's V12 weighing in at 496 lbs (225 kg).
6-Speed with a Ceramic Clutch
Power is transferred to the rear wheels through a newly developed six-speed manual transmission. Attached is a conventional clutch which has long since disappeared in both the Ferrari Enzo and Mercedes-Benz SLR. Porsche have made the clutch a technical highlight of the car by reducing its size and weight by several degrees.
Called Porsche Ceramic Composite Clutch (PCCC), this two-plate clutch is made of ceramic composites. Such materials not only help reduce the rotational masses of the clutch by a factor of ten, but offer less wear than conventional material. Combined with a lightweight flywheel rotational mass of the engine is exceptionally light.
Another highlight of this clutch is it's short diameter of only 6.5 inches (165 mm). At such a height the transmission and engine are very short and mounted low in the chassis. Just how low? Well the crankshaft rotates just 4.0 inches (102 mm) from the floor and the transmission actually sits lower than the rear differential.
CFP Chassis
Providing a basis for the Carrera GT is a carbon fiber monocoque with carbon-fiber-reinforced plastic (CFP) sub frames. Among the carbon body and carbon frame, metal pieces are few and far between. For instance on the chassis, the front rails, a-post inserts, fuel cell and suspension are the only major non-carbon elements.
The chassis is manufactured by a company called ATR. They are specialist Italian carbon fiber manufacturer which coincidentally make the tubs for the Ferrari Enzo. Production at ATR is two complete chassis per day.
A carbon rear sub frame isolates the entire drive train and rear suspension from the chassis. Having the engine completely supported CFP materials is new concept to production car manufacturing. It was concept developed by Porsche's Motor Racing Division and is subject to patent.
Suspension elements include double wishbones with inboard damper and springs on all four wheels. The inboard dampers and springs are actuated by pushrod and dampers like the setup used by every Formula One constructor.
Braking on all four corners is executed by the capable Porsche Ceramic Composite Brake (PCCB) system and for the first time on fifteen inch rotors. Consisting of ceramic discs and composite pads the system is lightweight and resistant to corrosion. PCCB reduces the unsprung weight of the braking system by fifty percent. Four channel ABS comes standard.
Attached to the braking system are forged magnesium wheels which weigh less than the tires wrapped around them. Michelin makes the only tire approved for the Carerra GT. They feature a soft compound rubber on the outer one third of the tread. It is suggested by Porsche that these tires need replacement every 15000 miles.
Aerodynamics
A large rear wing provides down force at the rear of the car. As the car reaches 75 mph (120 km/h) it electro-hydraulically raises an additional 6 inches (16 cm) for increased stability. At top speed the combined down force of the front and rear wheels total 639 pounds (290 kgs).
Apart from the wing, most of the Carrera GT's down force comes from its under tray. The entire tray is manufactured from carbon fiber and is attached to the chassis, engine mounts and crash structure. Creating down force with such a device is efficient as it does not impair the car's drag coefficient. A diffuser and air flow ducts provide additional ground effect.
Further aerodynamic attention is applied to the lower wishbones. They are made of efficiently shaped steel tubes which do not interfere with the aerodynamics underneath the car.
Electronics
To ensure control under all situations, the Carrera GT has a four channel anti-lock braking system and anti-spin control (ASC) to prevent excessive wheel spin. Traction control is standard. 'Should he/she wish to enjoy the thrill of dynamic driving of the highest racing standard the driver can switch off the complete traction control function by pressing a button in the centre console.' says Porsche.
Comfort
Porsche describe the Carrera's clean interior as a function-oriented ambience and a cockpit free of all extraneous detail. Only high-tech materials such as carbon, magnesium and leather adorn most surfaces.
Information is clearly presented in a classic Porsche instrument cluster which replaces the LCD screen featured on the concept car. The car also uses the 911 steering wheel which doesn't follow the F1 trend to stick as many functions on the wheel as possible. This old-school approach is a refreshing change, contributing to the GT's ambiance and ensuring it will remain a timeless design.
Extending into the dash is a centre console covered in magnesium. Attached sits a birch/ash shifter which is the only piece of wood found in this carbon-laden car. It specifically pays homage to Porsches 917 which sported a balsa-wood gear lever. Balsa was the optimum material for the job, it was extremely light, but most importantly added to the character of the 917.
Amenities such a Bose stereo system and air conditioning are optionally offered.
For closed top driving, two carbon fiber panels can be attached to the roof. At a low weight of just 6.4 lbs (2.4 kgs) each, these panels are easily removable and can be stored in the front luggage compartment.
Conclusion
Comparison between the Carrera GT and Ferrari Enzo is inevitable. Having 48 more horsepower (35.8 kW), and weighing 33 lbs (15 kgs) less, the Enzo easily wins on the straight line. The Carrera GT on the other hand, features much more down force and might possibly catch up in the esses. In any case, if either car is superior, the margin is so narrow that both cars can really take the cake.
It is also important to mention that the Carrera GT isn't the fastest supercar. Had Porsche tried to chase the McLaren's performance figures, production (planned at 1500 cars), profitability and comfort would have suffered.
Sources & Further Reading
Davis, Matt. 'Porsche Carrera GT'. Octane, December 2003.
Harris, Chris. 'The Dazzling Carrera'. Autocar, September 2003.
Kacher, Georg. 'The Porsche We've All Been Waiting For'. CAR.
Meaden, Richard. 'Super Ferry Animal'. EVO, November 2003.
Simister, John. 'Gunning for Enzo'. EVO.
Stout, Pete. 'Porsche's Pinnacle'. Excellence, December 2003.
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