No Turbo for GTS and GT3 991.2.....

2015 Porsche 911 facelift - no turbo engines for 911 GTS and GT3
Revised flagship sports car to launch at the Frankfurt motor show in September, with new engines among the planned changes

Porsche's 911 is set for a major overhaul later this year ahead of the introduction of an all-new generation in 2018.

These latest spy pictures show the 911 Turbo and Targa facelift almost undisguised ahead of their debut at the Frankfurt motor show. The pictures show the daytime running lights, and also some interior shots with a slighty bigger infotainment screen and a red turbo boost button on the steering wheel.

Previous pictures, supplied by Porsche, revealed various prototypes of the refreshed 991-series model being put through their paces by a team of Porsche engineers on roads around Cape Town, South Africa.

Key among the changes to the iconic German sports car is the adoption of a new turbocharged flat six-cylinder engine in place of the 911's traditional naturally aspirated flat six unit.

Technical details remain scarce, although information obtained by Autocar confirms that the new engine shares its architecture, including its individual cylinder volume, with the smaller turbocharged horizontally opposed four-cylinder powerplant that Porsche boss Matthias Müller has already confirmed will see service in facelifted versions of the Boxster and Cayman when they are launched in 2016.

In the facelifted 911 Carrera, the turbocharged flat six has a capacity of 3.0 litres and a claimed 365bhp at 6500rpm. By comparison, the outgoing model runs a naturally aspirated 3.4-litre flat six with 345bhp at 7400rpm.

In the facelifted 911 Carrera S the capacity of the new turbocharged engine achieves a power output of around 414bhp, with 369lb ft of torque at just 1700rpm.

This is up by 20bhp and 44lb ft on the naturally aspirated 3.8-litre of its predecessor, which produces 394bhp and 324lb ft.

Porsche engineers say the new engine provides a big improvement in low-end tractability and enhanced flexibility across the rev range, which peaks at 7500rpm.

This results in a 0.4sec reduction in the 0-62mph time for the 911 Carrera at 4.2sec, with the 911 Carrera dropping 0.5sec at just 4.0sec with the optional seven-speed dual clutch automatic gearbox. Top speeds are said to remain the same as for the outgoing models, at 180mph and 189mph respectively.

A tuning kit to be made available through Porsche's Exclusive division will hike power to 444bhp – just 70bhp shy of the turbocharged 3.8-litre flat six used by the existing 911 Turbo.

Along with the power and torque gains, the new turbocharged engines used by the facelifted 911 Carrera and 911 Carrera S are claimed to return significantly better fuel economy. Nothing is official just yet, although the latter is now said to boast combined cycle fuel consumption figure of 37.7mpg.

This represents an improvement of 5.2mpg over the outgoing naturally aspirated powerplant when in combination with an optional seven-speed dual-clutch automatic gearbox. A sound symposer, which directs the exhaust noise into the body structure, has also been adopted to enhance the aural qualities of the 911's new turbocharged engine.

Also seen is a new steering wheel-mounted driving mode control offering the choice between four programs. Similar to the drive mode control of the 918 Spyder, it is among a myriad of detailed interior modifications made to the facelifted 911.

Along with the engine, Porsche has focused on improving the already haughty handling qualities of its iconic sports car with the adoption a four-wheel steer system on the 911 Carrera S.

Similar to the systems already used on the 911 Turbo and 911 GT3, it provides three degrees of counter steer on the rear wheels at speeds below 31mph and three degrees of parallel steering at speeds above 31mph.

Exterior styling changes include a revised front bumper which features active air ducts that close at speeds above 9mph and then open again at 105mph. The basic headlight shape remains but the internal graphics and standard Xenon projectors are new.

The door mirrors receive an LED blinker function, the tail-lights get revised LED graphics and the rear bumper features cooling slits to help extract hot air from the engine bay.

With the facelifted 911, Porsche is also making available a hydraulic lift function for the first time. It provides a 50mm increase in clearance at the front of the car.

Further developments include a lane change warning function that eschews the steering wheel vibration feature of most similar systems for an acoustic alarm.

Meanwhile, Porsche's new flat four-cylinder engines, which are rumoured to support 2.0 and 2.5-litre capacities, are currently under development at Porsche's Weissach R&D centre on the outskirts of Stuttgart in Germany. They will first be seen in the upcoming facelifted Boxster and Cayman.

They are not planned for the facelifted 911, although Müller indicates they are being discussed for the successor model due in 2018.

No turbo engines for 911 GTS and GT3

Porsche has excluded its upper-end 911 GTS and GT3 models from plans to give its 2016-model-year 911 an all-new twin-turbocharged flat six engine.

Both the facelifted 911 Carrera and Carrera S are set to receive forced-induction units for the first time. However, the higher-end models will continue with updated versions of their current naturally aspirated 3.8-litre flat six engines, officials from Porsche have confirmed.

Although they will continue with their existing engines, the facelifted 911 GTS and GT3 will benefit from chassis and interior upgrades that are also set to be introduced to the 911 Carrera and Carrera S.

These include a four-wheel steer system for the GTS. This system aims to improve the handling qualities of Porsche's sports car and is similar to the systems already used on the 911 Turbo and 911 GT3. It provides 3deg of counter- steer on the rear wheels at speeds below 31mph and 3deg of parallel steering at speeds above 31mph.

The facelifted sports cars will have a revised front bumper featuring active air ducts that close at speeds above 9mph and then open again at 105mph. The basic headlight shape remains unchanged, but the internal graphics and standard xenon projectors are new.

The door mirrors receive an LED blinker function, tail-lights get revised LED graphics and the rear bumper features cooling slits to help extract hot air from the engine bay.

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