I’d love one of these…
Tech data:
A legend re-born - new Porsche 911 GT3 unveiled in Geneva
• Purpose-built normally-aspirated 3.8-litre flat six engine develops 475 hp, rev limit 9,000rpm
• Seven-speed PDK double-clutch transmission with unique steering wheel paddle-shift
• Innovative active rear-wheel steering increases cornering agility and enhances high speed stability
• Acceleration from 0-62 mph in 3.5 seconds; top speed 196 mph
• Sub-7 min 30 secs lap time around Nürburgring-Nordschleife
• Available to order 4 March, priced from £100,540 – first UK RHD deliveries November 2013
The Porsche 911 celebrates its 50th anniversary in 2013, and there is perhaps no better way to begin the celebrations than by opening a fresh chapter in the arena of high performance sports cars with the new 911 GT3.
In 1999, the then-new 911 GT3 set the benchmark for road-going sports cars with the fastest ever production car lap of the Nürburgring-Nordschleife, and established a reputation for itself as the definitive circuit-bred sports car. A total of 14,145 GT3 cars have since been built, over four generations.
Now, the fifth generation of the 911 GT3 makes its debut at the Geneva Salon, and is set to take on the pole position among thoroughbred Porsche sports cars with naturally aspirated engines.
The engine, transmission, body and chassis are entirely new, extending the breadth of ability offered by the previous 911 GT3 by an impressive margin. Together, they ensure that the proven characteristics of this track-inspired sports car are preserved, while also allowing more sophisticated day-to-day suitability – not to mention a highly emotional ‘fun factor’.
The powertrain of the new 911 GT3 comprises a 3.8-litre flat engine developing 475 hp (350 kW) at 8,250 rpm, a Porsche Doppelkupplung (PDK) double-clutch gearbox, and high-traction rear-wheel drive.
The six-cylinder engine is based on that fitted in the 911 Carrera S, but shares only a few common parts. All other components, particularly the crankshaft and valve train, were specially adapted or developed for the GT3. For example, Porsche is once again using titanium connecting rods attached to forged pistons. These basic modifications set the stage for an extreme high-revolution engine capable of reaching up to 9,000 rpm. The dual-clutch gearbox is another feature specially developed for the GT3, with characteristics inspired by the sequential gearboxes used in motor racing, thus granting the driver further benefits when it comes to performance and dynamics.
The new 911 GT3 is designed for further gains in precision and lateral dynamics throughout. 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 suspension is still adjustable. The new, 20-inch forged alloy wheels with central locking are used for optimal contact with the road. Traditionally, the 911 GT3 comes as a two-seater based on the lightweight body of the current-generation 911 Carrera. However, the front and rear part are always model-specific. For this latest generation, the 911 GT3 is 44 millimetres wider than a 911 Carrera S across the rear axle. Another clear identifying feature is the large, fixed rear wing. This makes a decisive contribution to the exemplary aerodynamics of the new 911 GT3, which combines low air resistance with a further increase in negative lift (downforce).
As a result, the new 911 GT3 once again sets fresh record performance values. At full acceleration from a standstill, 0-62mph is passed after just 3.5 seconds, and 124 mph in less than 12 seconds. The top speed of 195 mph is reached in seventh (and thus top gear) of the PDK transmission. The lap time on the Nürburgring-Nordschleife is even more impressive: the new 911 GT3 completed this track, commonly regarded as the most difficult in the world, in less than 7:30 minutes. While every Porsche is proven around the Nürburgring, this credential is particularly relevant for the new model as around 80 per cent of 911 GT3 customers also drive their cars on race tracks.
Completely new sports engine with high-revving concept
The Porsche Motorsport Department has an entirely new engine for the 911 GT3. This characteristic flat-six is a synthesis of the previous GT3 high-performance engine, the potential of which had been largely exhausted, and the new powertrain generation of the current 911 Carrera series. For instance, the new engine comes with typical motor sports characteristics, such as dry sump lubrication, a high-revving capability and forged titanium components. These are combined with cutting-edge technologies of production engines such as direct petrol injection, demand-controlled oil pump, and lightweight design and materials. The resulting engine weighs around 25 kg less than the previous unit, and exudes motor sports performance values, thanks to a power output of 125 hp/litre of displacement.
The structural changes to the base engine had one principal goal: to develop the characteristic high-revving concept of the 911 GT3 further still. High engine speeds enable high performance gear changes, whereby the revolutions remain in the range of maximum power after shifting up.
The consistent development focus made it possible to increase the maximum engine speed to 9,000 rpm, enabling the 911 GT3 to reach peak performance values among street-legal vehicles.
Valve control by rocker lever
The foundation for this outstanding performance is the low moving mass of the crankshaft and valve train. As with the previous model, the new 911 GT3 features forged aluminium pistons and forged titanium connecting rods. Forging these highly stressed components means that they are particularly strong, and yet lightweight. Furthermore, besides the hollowed valves, the new valve rocker arm control was a prerequisite for getting up to very high speed ranges. The low moving masses mean that the 911 GT3 engine also has unique speed dynamics with excellent response across the entire rev range.
The focus of the new development was the cylinder heads, which differ fundamentally from those of the base engine, and were specifically developed for the 911 GT3. To enable peak performance and engine speeds, the new cylinder heads feature 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 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 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.
As was the case in the previous-generation engine, Porsche is once again using the variable valve control system VarioCam. The continuous angle adjustment of the camshafts allows both high torque and high performance levels, and contributes to the meeting of emissions laws. The vane adjuster is made of aluminium to reduce weight. Each cylinder head is equipped with an integrated actuator for one of the high-pressure pumps of the direct petrol injection system. Unlike the base engine, which is supplied by an axially-arranged high pressure pump, the new 911 GT3 therefore comes with two radially-driven high pressure pumps.
First GT3 engine with direct petrol injection boosts power, efficiency
For the first time, Porsche has opted for a 911 GT3 engine with direct petrol injection. Compared with the previously used conventional manifold injection, this technology has proven itself in Porsche sports cars, since it permits higher power and torque, as well as yielding higher efficiency and lower CO2 emissions.
For use in the 911 GT3, this technology has been developed further, specifically with performance in mind, and features a specially developed injection system with multi-hole injectors and significantly higher injection pressure. Compared with the swirl injectors of the 911 Carrera models, multi-hole injectors provide a larger usable range of fuel quantity injected. The new GT3 comes with six-hole injectors, which permit sensitive injection with small throughputs and high maximum throughput for high engine performance.
The two fuel pumps generate a system pressure of up to 200 bar. This means more fuel can be injected, which is also sprayed more finely. As the designated sports car for the race track, a dry sump oil supply continues to be used for the 911 GT3. This meant that the oil pan had to be entirely re-developed. Just like the base engine, the high-performance engine is equipped with four suction points in the cylinder heads, an extraction in the oil pan, and an oil pressure pump. The engine of the 911 GT3 has two additional suction points in the oil pan at the front and rear, so as to be able to safely transfer oil to a separate oil tank during heavy acceleration and braking phases.
Dynamic engine mounts fitted as standard
The standard equipment of the new 911 GT3 now includes a more advanced generation of the previously optional dynamic engine mounts, which were specially tuned. The controller uses the present 911 GT3 sensors to detect a particularly dynamic driving style, and consequently stiffen the normally elastic engine mount. For this purpose, the bearings are filled with a sealed liquid containing magnetic particles, which changes in viscosity when an electric field is passed through. This emphasises comfort in everyday driving; on the race track, on the other hand, disturbing mass impulses from the engine during cornering and braking are compensated. Another advantage is the improved traction when accelerating from a standstill.
The intake system of the new 911 GT3 engine is also a synthesis of high-performance components that are based on the basic design. The air inlet is a specific plenum on the rear engine lid, which operates according to the ram-air principle and uses the air flow across the body for increased intake manifold pressure. From the double-flow air filter, this is followed by the flow and resistance-optimised air intake system, which was largely adopted from the current-generation 911 Carrera up to the throttle valve.
The plastic resonance intake manifold is also completely new. It is not only lighter than the aluminium system of the predecessor model, but also larger with further aerodynamic improvements. The induction system principle already ensured a fuller torque curve in the previous model. This was further developed and specifically tuned for the new engine.
As was the case with the predecessor, the new 911 GT3 also offers the driver the possibility of increasing the pull of the engine in the mid rev-range at the press of a button. When activated, the back-pressure in the sports exhaust system is further reduced, improving gas exchange and thus increasing the torque between 3,000 rpm to 4,000 rpm by up to 35 Nm.
Switchable sports exhaust system with special exhaust manifolds
Naturally, the new 911 GT3 still comes with a sports exhaust system, which was largely adopted from the previous model. This means that a high-performance system with powerful fan-type exhaust pipes and two catalysts is used, which are close to the engine and integrated into the manifolds. The two switchable front silencers and a common rear silencer with two central tailpipes ensure that the 911 GT3 meets the requirements for road use.
Porsche Doppelkupplung (PDK) with special 911 GT3 layout
The dual-clutch transmission (Porsche Doppelkupplung – PDK) originates from Porsche racing, and with the 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 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 race track 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 achieved using two paddles on the steering wheel, the left-hand for upshifts and the right-hand 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 car. 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: ‘lightning shifts’ with extremely short reaction and gearshift times
Gear-shifting strategy and response times of the 911 GT3 PDK have been consistently designed for maximum performance, and both are fundamentally different to 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, lightning 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: the de-clutching function of the 911 GT3 PDK
The dynamics of a sports car driven to achieve optimum lap times is also determined by the clutch. That is 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 very rapidly 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 understeering in a wet curve by pulling the paddles, and thus ‘dip the clutch’ and re-direct additional cornering force to the wheels of the front axle.