Design Review Of The Porsche Carrera GT
#1
12-18-2008, 03:01 PM
Design Review Of The Porsche Carrera GT 
Design review of the CGT
An owners retrospective by member RufMD
Anyone entertaining the idea of purchasing a Carrera GT should have an idea of what they are getting into....with that in mind, allow me to indulge a bit. The Carrera GT is simply a sensational car with many firsts in its design and construction. The design ethos was to create the purest race car experience for the road, with no compromise in driver comfort and the implementation of all that Porsche had learned from its motorsports success. The latest materials were used to minimize weight, increase power, while maintaining torsional rigidity for maximum dynamic performance. Porsche used a carbon fiber monocoque and engine/transmission mounts made from carbon reinforced plastic. All body panels are made from carbon fiber, as are the doors, wheel arches, floor and body undertray. The engine subframe assembly is entirely constructed of carbon fiber, an industry first. Magnesium is utilized in the center console, door handles, various switches and handles for the two roof halves. The wheels are produced from forged magnesium process, used for the first time ever in a production car. As a result, maximum weight savings are achieved, demonstrated by roof halves each weighing 2.5 kilos ! The wheels are 25% lighter than conventional aluminum wheels. The combination of a carbon monocoque and carbon subframe assemblies is an industry first for a production car and the entire carbon fiber chassis weighs an astonishing 100kg.
The engine in the Carrera GT is a direct developmental descendant of the 5.5L V10 originally designed for motorsport racing. It is enlarged to 5.7L, has four valves per cylinder and produces 612hp in production form with 435ft lbs torque at 5750 rpm. Lightweight titanium internals are utilized to achieve a maximum engine speed of 8400 rpm. A top speed of 205 mph and various independent tests demonstrating a 0-60 time of 3.5 seconds are indicative of the awesome power of this engine.
The gearbox is a 6 speed lightweight unit with a carbon ceramic clutch (PCCC) which is another industry first. The clutch is a multi-plate pack with a diameter of just 6.65”. This allows the transmission and engine to be mounted low in the chassis to lower the center of gravity. The engine is coupled with a lightweight flywheel which gives it instantaneous responsiveness. The clutch life is designed to exceed conventional clutch examples. The gearshift lever is mounted high in the center console for ergonomic reasons, and is topped with a wooden shift knob in homage to the legendary 917 racers that had balsa shift knobs to reduce weight…a perfect way to honor this cars tremendous bloodline. The Carrera GT’s oil tank is forged around the transmission in a further effort to reduce weight and space.
The brakes on the Carrera GT are the PCCB types first introduced on the 996 GT2. These are 6 piston calipers on massive 15 inch ceramic disks front and rear. These are 50% lighter than their iron counterparts. Coupled with the lightweight magnesium wheels are 19 inch and 20 inch tires specifically designed for the Carrera GT. The wheels are fastened with center lock nuts, color coded in blue or red for each side of the vehicle to prevent stripping.
The innovative suspension comes straight from motorsports. The springs and dampers use stainless steel pushrods and pivots fitted inside the carbon fiber chassis. The double wishbone suspension on the front and rear coupled with these pushrods gives tremendous toe-in stiffness and rigidity in maximum driving conditions. By moving the suspension components inboard, engineers reduced unsprung weight and further shifted weight to the center of the car. This combined with the low set position of the engine and gearbox results in tremendous stability and very minimal body roll.
All of the innovations used to maximize performance did not lead Porsche designers astray from driver comfort. The interior is leather clad, with a superb driving position and easy functionality of all controls. The radio/cd changer is combined with a navigation system in a tidy lightweight unit. The seats are supportive, firm and made of a carbon fiber shell resulting in a 10kg weight per seat. The pedals are floor hinged in true racing style. There are storage compartments placed within the door assemblies to maximize space. Front and side passenger airbags coupled with side impact bars and crush zones combine to aid passenger safety. A five piece luggage set in the matching interior leather adds an elegant component to this superb supercar. 1270 total were produced, 604 or so made it the the USA.
The Driving Experience
The efforts of Porsche engineers in implementing years of motorsports knowledge and innovation, has resulted in a truly wonderful driving experience. At the instant the left handed key is twisted and the engine barks into life, the driver realizes a special experience is in store. The engine note on startup is startling…a sudden sonorous bark that settles into an aggressive steady snarl punctuated by bursts of wail at the stab of the right foot. The lightweight engine internals result in instant engine response….I would describe it’s as almost “motorcycle” revving in nature. The engine note at the tail pipe is described by many as one of the most intoxicating sounds ever heard in a sports car. For the uninitiated, this often results in looks of disbelief and wide grins….an audio delight sure to satisfy the most demanding exhaust enthusiast !
Once engine fluids are at operating temperature, the gear is engaged and the clutch is let out. This can be a cause for consternation for unsuspecting drivers as the lightweight clutch and flywheel combo result in a racecar propensity to stall. If the clutch is let out without any throttle input, the traction control/engine management software will not permit a stall and a smooth takeaway results. With little practice, feathering of the throttle is possible for more aggressive starts.
As the car moves at low speed, there is a chatter evident in the drive train that smooths to an aggressive wail as engine speed builds. A quick grab of second gear with instant throttle input results in shattering acceleration with an occasional flicker of the traction control light as the software struggles to keep the car planted….third gear….you remain firmly planted in the seat as the speedometer flies to the right, the engine now firmly in an screaming wail.
Am I biased ? Just a bit
Jas D
