Porsche 911 GT3, 2014

 

 

 Porsche 911 GT3, 2014

Every Porsche has a race car at its heart. And never was the close relation to car racing so tangible. The new Porsche 911 GT3 stands for a redefined, even more emotional driving experience. The sports car that was developed from scratch offers even more dynamism and refined everyday practicality at the highest level.

With the GT3, Porsche is marking this 911 anniversary year by opening a new chapter in the area of high performance sports cars for circuit tracks. Both engine and transmission, as well as body and chassis are entirely new, and extend the 911 GT3 concept with an impressive performance leap. This is due to the new active rear-wheel steering, and the GT3-specific Porsche dual-clutch transmission with the characteristics of a sequential gearbox used in motor racing. Following the total production of 14,145 GT3 cars since 1999, the fifth generation of the 911 GT3, an all-round redevelopment, is set to take on the pole position among the thoroughbred Porsche sports cars with naturally aspirated engines.

The mission of the Porsche 911 GT3 is unmistakable: driving dynamics. Each and every relevant detail has been fine-tuned to that. The result is impressive: the new 911 GT3 laps the Nürburgring Northern Loop, indisputably the most challenging race track in the world, in a mere 7:25 minutes. A benchmark of great significance for the sportiest 911 with a naturally aspirated engine. Because around 80 percent of all 911 GT3 vehicles are also driven on race tracks.

Drive system and chassis of the new 911 GT3 have been systematically developed to even better performance, precision and transverse dynamics. Additionally, Porsche is using active rear-wheel steering for the first time. Depending on the speed, the system steers in the opposite or the same direction as the front wheels, thereby improving agility and stability. Among the other new driving dynamics features are the electronically controlled, fully variable rear differential lock, and the dynamic engine mounts. The height, toe and camber of the newly developed all-aluminium chassis are still adjustable. The new, 20-inch forged alloy wheels with central locking are used for optimal road contact.

New high-performance drive system with cutting-edge technology
Porsche has developed an entirely new engine for the 911 GT3. For the first time, the classical six-cylinder naturally aspirated engine has direct petrol injection in the racing car-like 911, combined with high-performance elements such as dry sump lubrication, titanium connecting rods and forged pistons.

In combination with valve control by rocker lever, an extremely high-revving engine capable of reaching up to 9,000 rpm emerged. For the driver, this means an even broader engine speed range that can bring decisive time advantages on the race track. The speedy response of the drive system is enhanced by the new power transmission without any interruption in propulsive power. As the first 911 GT3, the new model has a Porsche Doppelkupplung dual-clutch transmission (PDK) that had been originally developed for racing and has now made a comeback in a perfected form. The PDK is another feature specially developed for the 911 GT3, with characteristics directly inspired by the sequential gearboxes used in motor racing, thus granting the driver further benefits when it comes to performance, dynamics and driving fun.

Fascinating sports engine with high-revving concept
The new engine of the Porsche 911 GT3 is based on the six-cylinder used in the current 911 Carrera generation. The structural changes to the base engine had one principal goal: to develop the characteristic 911 GT3 high-revving concept further. High speeds enable high performance and gear changes, whereby the revolutions remain in the range of maximum power after shifting up. Thus the six-cylinder reaches its maximum performance of 475 hp (350 kW) at 8,250 rpm; the nominal torque of 440 Newton metres (Nm) is available at 6,250 rpm. The consistent development focus made it possible to increase the maximum speed to 9,000 rpm. This enables the 911 GT3 to reach peak performance values among street-legal vehicles. The result is a drive system that ventures even further into the racing range than ever before with a litre performance of 125 hp per litre.

Special cylinder heads with rocker arm control from motor racing
The focus of the new development were the cylinder heads, which differ fundamentally from those of the base engine, and were specifically developed for the 911 GT3. To enable peak performance values and engine speeds, the new cylinder heads are equipped with large intake and exhaust ports, large valves, and separate valve control with rocker arm. Cooling and oil supply are also particularly powerful to account for the high loads.

The valve actuation via rocker arms with hydraulic valve clearance compensation is another unique feature. The concept embodied in the Porsche 911 GT3 engine originates from racing and allows very high engine speeds on the one hand, while the other cams with performance-oriented profiles permit for large strokes and long valve opening times. The advantage of the rocker arm control is mainly in the low moving masses that allow high engine speeds, and the large contact area between the cam and rocker arm.

Advanced dry sump lubrication ensures the oil supply
The typically high and frequent lateral acceleration occurring with an ambitious driving style on the race track makes high demands on the oil supply. That's why the 911 GT3, as previously, has dry sump lubrication, i.e. the oil is siphoned permanently from the oil pan and is stored in a separate receptacle. In addition, the new 911 GT3 engine has for the first time an oil separator, a construction that also originates in racing. The oil separator consists of a cover between the crankcase and the oil pan featuring 18 single holes (three per cylinder) with crescent-shaped blades. Especially with high torques, the splash oil stirred up by the crankshaft is separated at the crescent-shaped blades ("planed") into the oil pan. Thus the amount of splash oil in the crankcase is lessened and as a consequence the so-called splashing losses of the engine are reduced. Alongside the demand-controlled oil pump, the new 911 GT3 also has two splash oil nozzles per piston that are opened in tandem depending on the temperature, load and torque. This guarantees an intensive cooling of the pistons, which are subject to high thermal loads.

More torque at the press of a button
As was the case with the predecessor, the new 911 GT3 also offers the driver the possibility of increasing the torque in the mid range at the press of a button. When activated, the backpressure in the sports exhaust system is further reduced, improving gas exchange, thus increasing the torque in the 3,000 rpm to 4,000 rpm range considerably again.

Dual-clutch transmission PDK with special 911 GT3 layout
The dual-clutch transmission (PDK) originates from Porsche racing. With the Porsche 911 GT3, it returns to the racetrack: the motor sports engineers have revised the PDK extensively both in terms of mechanics and control technology for the new high-performance sports car.

The resulting transmission provides the driver with all the essential driving dynamics of the previous manual transmission, complemented with the performance benefits of the dual-clutch transmission. During racetrack use, it can therefore be driven much like a sequential manual gearbox - with even more performance and emotional driving fun.

Two modes are available to the driver: manual shifting or the adaptive shift programme. Manual shifting is done using two paddles on the steering wheel, the right for upshifts and the left for downshifts. Shorter shifting travel and optimised actuating force result in even faster gearshifts with concise feedback, similar to the operating characteristics of the 911 GT3 Cup race cars. Alternatively, the driver can also shift using the selector lever, with a shift pattern based on that used in professional motor sports: shifting up is done by pulling the lever back, shifting down by pushing it forward.

Ready for the racetrack: "lighting shifts" with extremely short reaction and gearshift times

Gearshifting strategy and response times of the 911 GT3 PDK were consistently designed for maximum performance, and are fundamentally different from the other Porsche sports cars. This becomes apparent to the driver during manual upshifts in the form of a "lightning shift," which permits reaction times of less than 100 milliseconds. To enhance driving performance, lighting shifts are implemented with a torque overshoot, and the gear change is conducted with a highly dynamic adaptation of the engine speed to the newly selected gear. The switching times are in a range that was previously reserved for the world of motor sports.

Paddle-neutral: de-clutching function in the 911 GT3 PDK
The dynamics of a sports car driven to optimum lap times is also determined by the clutch. That's why the PDK comes with a "paddle-neutral" feature. If the driver pulls both shift paddles simultaneously, the clutches of the PDK are opened, and the flow of power between the engine and drive is cut off. Once both shift paddles are released, the clutch engages at lightning speed if the PSM is switched off. With PSM switched on, the clutch is closed quickly, but in a less pulsed manner.

This function offers two principal advantages: the driver can, for example, neutralise the driving behaviour of the vehicle when oversteering in a wet curve by pulling the paddles, thus redirecting additional cornering force to the wheels of the rear axle. The second aspect relates to individual influence of the driving dynamics due to the pulsed onset of the driving force when engaging the clutch. Comparable to a traditional coupling with a manual transmission, the rear of the vehicle can be consciously destabilised for dynamic leaning into the curve. Furthermore, the driver can use the paddle-neutral for accelerating from a standstill. As is the case with manual transmission vehicles, the driver alone decides on how to accelerate using clutch and accelerator foot, without any assistance from drive and dynamic handling control systems.

Adaptive shifting with sports strategies
or the first time, the PDK provides the driver of the new 911 GT3 with the alternative of leaving gearshifting to the adaptive transmission control. In principle, the PDK of the new 911 GT3 comes with two gearshifting strategies: Normal and PDK Sport. This means that the gear changes of the new Porsche 911 GT3 are always fast. Gear shifts and shift points are adapted to the dynamics of the driver.

The PDK Sport mode is activated by pressing the correspondingly labelled button on the centre console. In this mode, the PDK uses shift maps that are tailored to the requirements of pure circuit race track operation. Gears are held longer, and upshifts occur at higher engine speeds. The circuit race track optimisation also entails that the shifting programme is still performance oriented, even at a moderately sporty driving style. The high-performance sports car is therefore always running at the performance-oriented operating points, and increased traction is available at any time without the driver having to shift gears.