CAR interviews 'Mr GT3' Andreas Preuninger

The latest Porsche 911 GT3 boasts an all-new 469bhp 3.8-litre flat-six and is quicker than the legendary GT3 RS 4.0, but fans of this hardcore icon have voiced their concern over its new dual-clutch PDK gearbox and its steering (both the electric rack inherited from the 991-generation Carrera, and the new rear-axle steering). 

Ahead of the 911 GT3's unveil at the 2013 Geneva show this week, CAR had exclusive access to the car, and to the man who headed the team that engineered it: Porsche's head of GT series production Andreas Preuninger.

Preuninger built the first 996 GT3, and has been doing his  job for the past 12 years. We asked him all about the new GT3, including those controversial issues. Here are his answers...

Andreas Preuninger on the philosophy of the new GT3…

'The GT3 has become so important for Porsche – we have to offer a GT3 variant with every new 911. It's been a niche in the past, but not anymore, especially because so many competitors are pushing into the sector. The bandwidth in which the new car is useable is incredible: it's a brilliant daily drive, but it's also got an even more sporting edged biased towards track capability.'

On the death of the motorsport-derived ‘Mezger’ engine…

'The 4.0-litre RS with the 'Mezger' engine was not in our long-term planning, but a skunkworks project. The original plan was for the last Mezger engine to feature in the 3.8 RS and GT2 RS, but we decided to make the 4.0 RS, as one last goodbye, with all the things we learnt from the GT2 RS. It’s definitely the last time we will use that engine in a road car – I promised everyone and I will be true to my word.'

On the new engine…

'There’s a lot of doubt, in the almost devout community of GT3 buyers. It’s not something out of the 911 Carrera with a bigger camshaft: the only parts shared with the 991 Carrera S engine are the casting of the crankcase and the bolts for the cylinder head. Full stop. That’s it. There’s a new crank, titanium con-rods, forged aluminium pistons, and a completely new cylinder head with a revolutionary valvetrain that you won’t find in any other street-legal car – there are no tappets, instead we use rocker arms like in a motorcycle so the weight goes down dramatically. The new engine is around 25kg lighter than the Mezger. And that gives us room for the extra rpms…

'We were very, very aware that this engine needs to have the same character, the same amount of character, the same specialness as the Mezger had. We have absolutely made it: the new engine has the same impatient idle, this ‘Come on, go!’ attitude and it revs even higher – to 9000rpm. You wouldn’t believe the difference between 8500rpm and 9000rpm – it’s only a small difference numerically, but when you’re in the car the experience is a whole new world. The way the engine goes to the redline, the sounds the engine makes is so mechanically crisp and emotional that it brings a totally new personality to the GT3.

'We decided to make an emotional link to the GT3 RS 4.0, the king of the GT3s, so the new GT3 has the same specific output: 123bhp/litre. We’re on par, but I would say 469bhp is conservative. I like ‘low-balling’ with GT3s – we could say 500bhp and that would be perfectly homologatable, but I’d rather say 469bhp and have the GT3 beat all the 550bhp cars. This is more Porsche.'

On the new dual-clutch PDK gearbox…

'I’ve being doing this job for 12 years, I made the first GT3, and everybody knows I’m a very puristic driver. I want the car to be analogue, I want maximum driver involvement. That’s why we chose not to use a PDK ‘box until now – the involvement was not at the point where it should be for the GT3. The weight was another issue, too. So this time, for the first time, we decided to try out the PDK gearbox in parallel with the manual, and really feel what the difference was like. And feel is very important, for customers and myself – a very, very fast car where you don’t have any sensations isn’t worth the money. And coming from the other side we are under pressure from the competition, so I won’t sacrifice any performance just because someone wants to shift with a manual.

'The PDK gearbox is about 30kg heavier than the manual in the 997, and we have saved 25kg from the engine, so I said we should try it. The ‘box itself isn’t from the Carrera: there’s seven driving gears, not six plus overdrive, so you reach the top speed in seventh, And the programmes and hardware are totally different. The upshifts are beyond comparison on the market – less than 100ms – and it’s so much fun to use it: the sensation you get when you drive the car is like having a sequential race gearbox, not a flappy paddle system.

'We added a ‘Hooligan mode’ so you can do donuts in the car. Or, let’s say you have a 2nd gear curve, it’s wet, there’s nobody around and you wanted to drift. How do you do that in the manual? You dip the clutch and press the throttle to get the car around. That’s not possible in a normal automatic, but it is in the GT3: if you pull both paddles it engages neutral so you can 'clutch kick' the GT3. Same for race starts – you can dial up more wheelspin than the computer will give you. This was a major programme with the gearbox development to ensure you could play around with the PDK.'

On when the manual gearbox was ruled out…

'We ruled out the manual gearbox in back to-back comparisons last summer. On every shift with the PDK is more emotional, because for the first time when you shift at 9000rpm there’s a bham! in the exhaust, and this gives you goosebumps. It blips the throttle on the downshifts, and on a road you don’t know you can go very fast with both hands on the wheel. And on a race track the PDK gains three-quarters of a car length with every shift, so after a long straight you’re ahead of the other car and can turn-in in front of him. It just works. This is the big news.

'There’s no chance of a manual. We don’t want to offer too many options on our GT cars. And if you’ve got a manual and a PDK you’ve got to have different set-ups for the suspension, the aero, the tyres, everything. We are a small team and can only concentrate on one car.'

On the GT3’s new electric steering…

'The steering was a challenge, as we’re changing to the electromechanical system. I think we had a benchmark system in the last GT3, and it was my target to get it as least as good as that system. It was not easy as the GT3 driver needs to feel all the feedback the tyres give him, all the forces in the steering rods, in all conditions, but we made a huge effort to get it exactly the way it was in the last car. I promise no one will notice that it is not the steering we had in the GT3 RS 4.0. I’m 100% sure of that. The filters are gone!'

On active rear-wheel steering…

'I was shying away from it. I believed it was not puristic enough. But we tried it out and it helps so much. And you don’t notice it because it’s simply a steering rod system, not some electronic gizmo. We can change the angle of the rear wheels by 1.5 degrees, which doesn’t sound like much but the effect is tremendous. I couldn’t believe how much better the agility of the car and the turn-in capability are with the system. I did a back-to-back test, in one car with the system able to be turned off by a switch, and couldn’t believe the difference. And on track, the tyres last longer, so you are more consistent.

'The steering rods add 5-6kg, plus the system draws more current so yo need a bigger battery, but back-to-back with a car with a lightweight battery, no rear-steer and a manual gearbox (and in that configuration the car is lighter than a 997 GT3) this new GT3 is so much more confidence inspiring. And faster, no matter where you drive it. It simply didn’t make sense not to use all these systems to take on all the other competitors out there.'

By Ben Pulman