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Porsche 911 GT3 and GT3 Cup 2013: The GT revolutions of the 991 series

Rossen Gargolov
Porsche 911 GT3 and GT3 Cup 2013
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' At first I expect a lot of cries for help - the purist car is becoming an electronic animal, 'says Andreas Preuninger, project manager GT models at Porsche while he looks at his youngest pupil basking in the studio light.

Novelty in the Porsche 911 GT3 Hostorie

The reason for the outcry could be a novelty in the be the model history of the Porsche 911 GT3 since 1999. The GT newcomer from the current 991 series not only works with electromechanical steering on the front axle, but also h at the start with rear-axle steering.

“It is not an active steering that incapacitates the driver. The car has gotten bigger, but when you drive it you get the feeling that it's gotten smaller, ”explains the project manager.

Suitability for everyday use has been improved

The development team tested the Porsche 911 GT3 with and without rear-axle steering. “The difference between a steered rear axle and a non-steered rear axle is striking. At speeds below 50 km /h, the rear wheels turn in the opposite direction when the front wheels are turned. At over 80 km /h, the system steers the rear wheels parallel to the turned front wheels, ”explains Preuninger. In addition to driving dynamics thanks to greater driving stability, everyday usability is said to have been improved by a smaller turning circle.

To achieve this, the engineers in the Porsche 911 GT3 are replacing the conventional toe links on the rear axle with tie rods with electromechanical actuators. As a result, the rear wheels steer up to 1.5 degrees in both directions, depending on the speed.

“This results in a virtual wheelbase shortening of around 15 centimeters at low speeds and with tight curve radii. At higher speeds, the wheelbase is virtually extended by 50 centimeters. Normally, the steering impulse from the front axle arrives at the rear axle with a slight phase delay. If the rear axle moves slightly at the same time as the front axle moves, I almost pretension the tire. That means the car builds up lateral force much earlier. That gives confidence and makes the car fast, ”explains Preuninger.

Rear-axle steering makes the car faster

Second Advantage of rear axle steering is supposed to be abe less tire wear. “The times after the second or third lap, when everything is really warm, are more constant and better,” says the GT3 maker. Speaking of tires. For the Porsche 911 GT3, Dunlop is developing a special specification of the Sport Maxx Race. “It has a high side force potential. You know exactly what the car is doing. We are already at a higher level here than in the past, ”says Preuniger enthusiastically about the new GT3 tires. In addition to the Sport Maxx Race, the Michelin Pilot Sport Cup 2 will also be used on the 911 wing.

Preuninger opens the doors, which, like the roof, the fenders and the trunk lid, are made of aluminum. “For God's sake, he no longer has a manual gearbox, the purists will say. The new GT3 dual clutch transmission feels almost like a sequential racing transmission and not like the well-known PDK from the Porsche 911 Carrera, ”explains the project manager as he points to the selector lever in the cockpit.

Sportiest of all 911s only with PDK

After rear-axle steering, this is the second revolution in GT3 history: the sportiest of all 911s is only available with the vehicle for the time being Double clutch and no longer with manual gearbox. “PDK technology is so advanced now. The GT3 transmission has relatively little to do with the transmission application in the Carrera. We switch much faster. The PDK sports button causes additional gear increases. Compared to the Carrera, the shift travel of the paddles is reduced by 50 percent and is more precise with a clean attachment point. This alone enables us to reduce shift times by 50 milliseconds, ”says Preuniger, describing the differences in the transmission.

The developers also changed the PDK shift pattern based on the motorsport model - upshifting by pulling the selector lever, downshifting by pushing forward. Compared to the Porsche 911 Carrera, the gear ratios in the GT3 have also been shortened.

Instead of the mechanical lock of the predecessor, an electronically controlled rear differential lock is now to provide for traction. Thanks to a new PDK (paddle neutral) function, the frictional connection of the clutch can be interrupted while driving by pulling both steering wheel paddles. When the paddles are then released, the clutch can close again in a flash when the driving aids are deactivated. “This is a wonderful way to initiate a drift despite PDK”, promises the Porsche 911 GT3 man.

The project manager does not rule out a comeback of the conventional switch box for a later Porsche 911 GT3 RS model . “During the development phase, we also built a car with a manual transmission. The Porsche 911 GT3 with PDK has won every acceleration competition by a three-quarter car length advantage. In the Cup car, there is no longer the gear stick, we have that tooPaddle, ”says Preuninger of the power transmission while looking at the Porsche 991 GT3 Cup for the coming Supercup season.

Porsche- One-make cup racer with shift paddles on the steering wheel

The racing GT3, like the series Porsche 911 GT3, is mounted on the production line in Stuttgart-Zuffenhausen and uses a sequential six-speed claw-type transmission that is shifted for the first time in a Porsche one-make cup racer using paddles on the steering wheel becomes. In addition to a newly developed racing brake system and a new axle geometry, the Cup 911 uses an old friend. The 3.8-liter boxer, which is based on the 997 GT3 RS engine, is still sawing in the rear. With 460 hp, the Cup engine has an output of ten hp more.

The newly developed 3.8-liter boxer for the road vehicle is based on the Porsche 911 Carrera S engine, but uses few identical parts. The high-speed engine with 475 hp (previously 435 hp) rotates up to 9,000 rpm and for the first time has direct injection. In addition to forged aluminum pistons and titanium connecting rods, Porsche is relying on a new valve control system.

“We don't use bucket tappets in the cylinder head, but very light rocker arms, like on a motorcycle. The moving masses are correspondingly lower, which allows high speeds, ”says Preuniger. With a smile, the GT project manager makes our mouths even waterier: “From 8,000 onwards, the sound becomes metallic hammering. It's really amazing what it makes a car turn 8,500 or 9,000. The exhaust sound is reminiscent of a WRC car. ”

Lap times keep falling

Not rally, but The predicted lap times that the Porsche 911 GT3 with its adjustable sports suspension and numerous aluminum components and 30 millimeters lowering is supposed to conjure up on the asphalt are suspicious of racing: Less than 7.30 minutes on the Nordschleife and 1.08 minutes on the small circuit in Hockenheim.

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