New 911 Carrera turbo kickstarts Porsche’s turbocharged future

New 911 Carrera turbo kickstarts Porsche’s turbocharged future:

Porsche’s Dr Erhard Mössle reveals all about the 911’s new boosted flat-sixes

For the first time in the Porsche 911’s 52-year history the Carrera and Carrera S models will use a turbocharged flat-six engine. It’s a move that will be met with some degree of resistance among purist sports car enthusiasts, but the switch to forced induction has resulted in the fastest and most powerful Carrera and Carrera S models to date.

Four years after the arrival of the seventh-generation 911, codenamed 991, Porsche has overhauled the mainstream models with new engines, revised chassis settings, facelifted bodywork and a new infotainment system. The mid-life refresh is intended to keep the 991 competitive in the sports car marketplace until a new model arrives in 2018.

Both the Carrera and Carrera S use an all-new 3-litre, twin-turbocharged six-cylinder boxer engine. Both versions boast 20bhp increases over the outgoing normally aspirated models, with peak outputs now having risen to 365bhp and 414bhp respectively. The Carrera S’s additional power can be attributed to its pair of turbochargers boosting at 1.1bar rather than the Carrera’s 0.9bar. The turbochargers are fixed-vane items rather than the 911 Turbo’s clever variable vane type.

Torque outputs have risen more substantially – by 44lb ft on each model – but peak torque is now available from just 1700rpm, right up to 5000rpm. For reference, the previous Carrera S delivered its peak torque at 5600rpm. The figures are 332lb ft and 369lb ft for each model.

With more power than ever the Carrera and Carrera S are faster than ever, too. With the PDK twin-clutch gearbox and Sport Chrono fitted the entry-level model will reach 62mph in 4.2 seconds – two tenths quicker than before – while the Carrera S also cuts two tenths from its 0-62mph dash to clock 3.9 seconds. Top speeds are now 183mph and 191mph.

Fuel consumption has been reduced by around 10 per cent across the board. Porsche claims a Carrera with PDK will now return 38.2mpg, with the S capable of 36.7mpg.

Straight line performance and fuel efficiency have benefited from the switch to turbocharging, then, but logic suggests that throttle response, exhaust note and top-end fireworks – between them the three factors that can make an engine memorable rather than just effective – will have taken a backwards step.

When asked if he can understand that apprehension, senior Porsche engineer Dr Erhard Mössle says, ‘Yes, of course I can! The normally aspirated six-cylinder boxer is a famous engine in the 911, but we face some challenges, not only in terms of fuel consumption and emissions, but also from our competitors. When you look at our competitor cars, like the Mercedes-AMG GT S or other cars with turbocharged engines, it’s getting harder to stay close to them with a normally aspirated engine.

‘We tried to model a normally aspirated engine and avoid turbo lag as much as possible,’ he adds. ‘A lot of detail work has gone into the system to improve response. For instance, when you come off the throttle the turbos keep spinning, so they are running at a higher speed when you get back on the throttle. We also have a new sports exhaust system that sounds really good. Yes, it’s different to a normally aspirated engine, but it sounds better than the 911 Turbo, more emotional.’

The seven-speed manual gearbox has been beefed up to deal with the extra torque. Its ratios – as well as those of the PDK gearbox – have been tweaked to suit the new turbo engine. Drive is apportioned between the rear wheels by a limited slip differential – purely mechanical in the Carrera and electronically controlled in the Carrera S.

The new engine is heavier than the unit it replaces – by around 40kg – which means more weight now sits over the rear axle. The rear spring and anti-roll bar rates have been wound up in response, while the front axle suspension settings have also been revised. Four-wheel steering has filtered down from the Turbo and GT3 models and is now standard fit on the Carrera and Carrera S. The system improves low speed manoeuvrability and adds high-speed stability.

Porsche Active Suspension Management is also standard fit on both models and the brake discs are now bigger in diameter, while the stock tyre is a Pirelli P Zero – up to 305mm at the rear on the Carrera S from 295mm.

Bodywork updates are limited to a revised front bumper design, new headlight and LED daytime running light layouts, vertical slats on the engine cover, more stylised rear lights and a new placement for the exhaust tips, plus a cleaner door handle design and new wheels. The frontal air intakes now feature active flaps, which close in certain conditions to improve aerodynamics and therefore fuel efficiency. A front axle lift is now available for the first time on the Carrera models.

Within the cabin is a new steering wheel, while a smaller, 360mm GT wheel is available as an optional extra, which features a new 918 Spyder-inspired switch for adjusting the car’s chassis and drivetrain modes. The fourth-generation Porsche Communication Management system is introduced here with a multi-touch screen, a smartphone style menu system and Apple Carplay preparation.

Porsche quotes a 7min 34sec Nurburgring time for the Carrera S – some six seconds quicker than the previous model. Impressively, that’s the same time Porsche claimed for the 997-generation GT2.

The normally aspirated 911 Carrera has become a thing of the past, but Mössle suggests Porsche might yet build a limited edition model – apart from the GT3 and RS version – that uses an atmospheric engine: ‘There will never be another series production normally aspirated 911,’ he says, ‘but maybe we will do some special edition cars.’

The facelifted Carrera 2 and 2S will arrive in UK showrooms before the end of the year, in both Coupe and Cabriolet bodystyles, with Carrera 4 versions due to follow within six months. UK prices are confirmed at £76,412 for the Carrera Coupe and £85,857 for the Carrera Cabriolet, and £85,253 for the Carrera S Coupe and £94,648 for the Carrera S Cabriolet. 

The full story on the new 911 Carrera turbo and exclusive pictures can be found in the November issue of evo, in stores from 9 September.

Dan Prosser

6 Sep 2015

(Via evo: News)