The rock star of the 911 range now comes with a PDK dual-clutch transmission - we catch the GT3's "rock concert" in its hometown
Red Hot  Chilli Pepper PHOTO: TORQUE

This fifth generation of the 911 "Gran Turismo Three" is a superb update on the GT3 design template. While the front splitter and rear wing look fabulous, they are there for function rather than fashion, although many poseurs would buy them for style alone. The coupe's rakish new lines were drawn by Porsche's all-important motorsport department, and the aero aids increase downforce by 20 per cent while keeping the drag coefficient at 0.33. That "fighter jet" rear wing provides less downforce than the full-width rear wing of the GT3 RS 4.0 (the run-out special edition of the superseded 997 series), but the latest GT3 doesn’t need so much downforce in the first place.

The cockpit hasn't been stripped down to save weight, apart from the deletion of the standard Carrera's backseats, so you still get audio and air-conditioning. The keen "pilot" can order Club Sport bucket seats with six-point harness, track-ready roll cage and fire extinguisher.

Almost everything to do with driving in the new GT3 has been modifi ed from its original Carrera S form, with the 3.8-litre flat-6 receiving the most attention. While the basic block is shared with the Carrera S, there are redesigned cylinder heads that now use a rocker lever to actuate the
cams, which allows for deeper and faster valve openings. The powerplant produces 475bhp, which equates to a whopping 125bhp per litre.

Like the previous GT3, the engine employs dry-sump lubrication. This isnecessary because around 80 per cent of all 911 GT3s are driven regularly on racetracks (according to Porsche's internal data). A newly introduced feature is an oil separator that reduces power-sapping oil splash in the crankcase. Like before, there's a userselectable
sports exhaust system that meets EU drive-by noise regulations and offers a more straight-through exhaust path at the press of a button. This raises the sound and torque levels.

Of course, the most controversial item in the new GT3 drivetrain is its PDK dual clutch transmission. There's no 7-speed manual option. Andreas Preuninger, head of Porsche Motorsports, told me that the PDK is better than a manual gearbox when setting lap times, but his marketing colleagues will probably add that an auto is also more sellable.

The GT3's PDK is no ordinary dualclutch. It has paddle-shifters rather than a long, sequential lever, so the driver can keep both his hands on the wheel when gunning through the gears. In the new GT3, Porsche's official testdriver Timo Kluck managed to lop two seconds off the GT3 RS 4.0's Nurburgring Northern Loop lap time, despite the old model's 25bhp-greater power and 60kg lower weight. The GT3's PDK is not only a quick device able to change gears in 100 milliseconds, it also has lower and more closely stacked ratios – seventh gear, for instance, is almost a direct drive, reaching the top speed of 315km/h at 9000rpm.

For the first time, Porsche is using an electronic differential, which supplements the existing mechanical affair. This setup enhances the GT3's ability to put power to the tarmac and maximises the grip of all four tyres, with up to 100 per cent of the engine's energy apportioned to any one of the wheels if needed.

The electronically controlled, fully variable rear differential lock also allows
the PSM (Porsche Stability Management) tech to incorporate torque vectoring.

The active roll stabilisation system that helps the Carrera S to grip the road like a leech has been replaced in the GT3 by conventional anti-roll bars, with firmer springs and a lower centre of gravity to provide even better resistance to body roll.

More impressive still is the GT3's active rear-wheel steering. It's a first for Porsche's GT road cars. The system, which adds 6kg to the kerb weight, uses two electro-mechanical actuators at the left and right side of the rear axle, in place of conventional control arms. These vary the steering angle of the rear wheels by up to 1.5 degrees, depending on the speed – in the same direction as the front wheels above 80km/h, and in the opposite direction below 50km/h.

The "counter-steer" cuts the car's turning circle, while the "same-steer"
reduces the car’s nervousness at high speed by giving it a virtual wheelbase increase of nearly 500mm. The active rear-wheel steering also helps the tyres to run less hot during track use, which improves their safety and durability.

Mindful of the criticism from hardcore petrolheads about the 991's electric power steering (EPS), the GT3's engineers rewrote the software algorithms to make the car's EPS feel like the hydraulic servo steering of the old 997 RS - it writhes a little in your hands, it "lives". This steering "fix" might be applied to the Carrera models in due course.

A more obvious GT3 party trick is the "paddle-neutral" feature. Pull both paddles simultaneously, the dual clutches of the PDK will open and the drivetrain's power flow is interrupted – release the paddles and the clutches re-engage in an instant. With your right foot planted on the throttle pedal, it’s like a "drop-clutch" 6000rpm take-off, with expensive Michelin rubber burned for most of first gear. Use "paddle-neutral" just as you enter a corner and the car goes into an oversteering drift. Amazing stuff.

Whether using "paddle-neutral" or the 911 PDK's standard Launch Control, the rear-drive GT3 guns from a standstill to 100km/h in a scorching 3.5 seconds – comparable to the all-new, all-wheel-drive 911 Turbo.

Ever since Porsche introduced the 996-series GT3, it has been making steady improvements to its special breed, with a breakthrough in the early 997 version, which uses PASM (Porsche Active Suspension Management) that allows a much broader range of damping than the fixed-rate type.

The newest-generation 991 GT3 continues to use PASM dampers, but they aren't the same ones found in the current Carrera, with Bilstein having made a bespoke set to suit the GT3 suspension, which has adjustable ride height, preloading of the springs, and variable camber. The suspension geometry is kept perfect with dedicated spherical rosejoints that do not allow any unnecessary movement. Remarkably, this supreme "low-frequency" control has been achieved without the ride suffering "high-frequency" harshness and excessive noise.

Even manhole covers and road repairs aren't transmitted from the chassis to the cabin, while ridges and crests are traversed without trouble. In fact, the new GT3 rides nearly as well as the "softer" Carrera S, and this is with gumball "super GT" tyres.

On any road or track, the 911 GT3 is ready to rock and roll. Its performance, suspension and steering come together beautifully to deliver an awesome drive experience every time. This Porsche chilli pepper is red, hot and a great pinnacle model – other than the new 911 Turbo and Turbo S, of course.

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This article first appeared in the October 2013 issue of Torque.


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