‘ONE LAST QUESTION,’ I SAY TO ANDREAS Prcuninger at the end of our interview. ‘Is this the best 911 GT3 ever?’ We’re standing in a chilly photographic studio on the outskirts of Stuttgart, just a few kilometres from Porsche’s research and development centre at Weissach. The head of the company’s GT-car division has spent the last 30 minutes or so talking me around the latest in a long and extraordinary line of stripped-down, pumped-up, track-ready 911s, pointing out every little refinement, every hard-won efficiency.
This new car is a development of the first-generation 991 GT3 rather than an all-new model, but every major component has been polished or honed to deliver more performance or less resistance. In among the tumbling list of minute tweaks and infinitesimal modifications are two standout headlines: the flat-six engine is now a 4-litre unit, superseding both the 3.8 in the previous GT3 and the 4.0 in the GT3 RS and 911 R, and buyers can now choose between a six-speed manual gearbox and a seven-speed PDK transmission.
‘Our main focus was on engine development,’ says Prcuninger. ‘Since we introduced the new engine platform in the previous GT3 we have used it in the GT3 RS and the R, and now in the [mid-engined] 911 RSR race car that came second at Daytona. As you would expect, we have been gaining confidence and experience with that platform and we are getting ideas to make it better – more powerful, more revvy, more longevity, everything. The engine we have now is a quantum leap from the 3.8 and a big step up even from the RS engine.’
The crankshaft is new and it now runs on bigger bearings. It’s also cross-drilled with a central-fed oil system, so all the oil that lubricates the conrod bearings comes through the centre of the crank. That approach requires much less pressure for the oil to reach all the vital components, which means less internal resistance and, ultimately, more power at the wheels. ‘That’s what we were looking for,’ says Preuninger. ‘Get internal resistance down and be more efficient.’
The piston rings are lighter and thinner while the cylinder liners are coated in a very low-friction material, which further cuts resistance. The new oil pumps are more efficient, too. The air intake, meanwhile, features a twin-flap system. A similar setup was used on the 4-litre Mezger engine fitted to the 997 GT3 RS 4.0, but previous versions of this engine used a single flap. ‘This greatly influences torque low down,’ says Preuninger. The only problem with having more parts is if something breaks it gets inhaled into the engine and, boom, it goes. We’ve found a way to make it completely bulletproof.
‘Everything is topped off by a completely new valvetrain. Whereas earlier incarnations of this engine used conventional hydraulic valve-lift adjusters, which require lots of oil pressure to operate, this version uses a completely rigid valvetrain, like in a race motorcycle. By deleting the hydraulic elements we can lower the forces in the valvetrain substantially-we’re talking 30 percent. We need less force to turn over the apparatus and less oil pressure. With that modification alone we gained about 10bhp.’
The results of all that development work are spectacular, on paper at least. Peak power is the same 493bhp as the outgoing 4-litre RS unit – ‘that’s 500 very conservative horsepower’ – while torque is rated at 339lb ft, which is the same as the GT3 RS engine and an increase of 15lb ft on the previous GT3. ‘The more interesting thing is when you look at the area beneath the torque curve,’ says Preuninger. ‘This is what gives this engine quite an edge over the 3.8.’ Impressively, despite the longer stroke needed to increase engine capacity over the 3.8, the new engine still revs to 9000rpm.
The GT3 RS and R engines revved only to 8800 and 8500rpm respectively, which was the main reason the smaller engine was actually more exciting at the top end. Porsche has now combined the longer stroke and higher output with the head-spinning 9000rpm rev limit. ‘The engine is like a firecracker exploding after 5000rpm,’ says Preuninger. ‘We understand this new platform now the way we understood the Mezger. It reacts completely differently to external inputs than the Mezger, so we had to rethink everything.
You get new ideas from racing, from experience, and you have time to test. We are quite happy now that we know how to make this engine very powerful and efficient at the same time. The result is in this car.’ Porsche caused a first-world furore when it dropped manual transmissions from its GT cars in 2013, but following the success of the manual-only Cayman GT4 and 911 R it was somewhat inevitable that this latest GT3 would be available with a choice of transmissions.
It’s clearly the outcome Preuninger had hoped for – Tm freaking out!’ he says about the return of the manual GT3 – and he goes on to explain the decision to go PDK-only on the previous GT3: ‘On that car we had a completely new platform, so we couldn’t concentrate on making both gearbox versions. We had to design for one. But after all this, who are we to say this is better or that is better? If you want to use the car on track, go for PDK, 100 per cent. If you occasionally go to the track and you’re looking for involvement and a car that makes you smile all the time, go for the manual.’
Preuninger can only guess what the split between PDK and manual will be among customers, but he estimates 60:40 in favour of the two-pedal option. Certain markets, however, including the US, will favour the manual transmission. It’s the same unit found in the 911 R, but it uses a dual-mass flywheel rather than a single-mass, which was an optional extra on the R. ‘We should address this point right now,’ he says, sternly. ‘Don’t take the single-mass flywheel from the R and try to be clever and put it on the new GT3. Why? You will ruin the engine. Believe me, we tried it.
But even with a dual-mass flywheel the engine is so fiery.’ The manual gearbox has a switchable throttle blip and drives through a mechanical limited-slip diff. The PDK car, meanwhile, uses a faster-reacting electronically controlled LSD. The twin-clutch transmission is the same as in the GT3 RS, with the same gearing, but slightly improved shift times. The chassis was perhaps the previous GT3’s ace card, but Preuninger’s team have still worked hard on the new car’s dynamics. The damper tuning has been revised and there are helper springs on the rear axle now, like on the GT3 RS, which give a little more pliancy over bumps. In the UK the tyres will be Michelin Pilot Sport Cup 2s, which have been further developed since being used on the previous GT3.
Cast-iron brake discs are standard fit and carbon-ceramics are available. The wheels, meanwhile, are the same design as before. ‘We loved the gen-one wheel so much [we kept it], but in matt black. I normally don’t like black wheels because you can’t see the point where the wheel starts and the tyre ends, but with the [body-coloured] pinstripe you can.’ Preuninger says the car uses the latest version of Porsche’s electric steering system, which has been improving steadily since first appearing on a Porsche Motorsport car on the previous GT3.
‘We learned a lot on the 911 R,’ he says, ‘so the steering feel is quite a leap in comparison. This car also uses the smaller, 360mm steering wheel.’ The rear-axle steering system has been carried over but with changes to the software that improve the car’s low-speed agility. The other major upgrade has been to the aerodynamics. ‘The aerodynamic efficiency of the car is way better,’ says Preuninger. ‘We have the same coefficient of drag as the last one, but we’ve got 20 per cent more downforce. We learned on the 911 R that we could get better downforce by addressing the underbody.’ New vanes and spoilers on the underbody accelerate the air underneath the car and shoot it directly to the new diffuser.
The rear spoiler also sits 20mm higher and 10mm further back, so it reaches into cleaner air. The maximum downforce figure is 155kg at top speed, matching the 997 GT3 RS. With more power, torque, improved aerodynamics and tweaks to the chassis and tyres, the new GT3 will inevitably be faster than the old car, with Preuninger anticipating a Ring time of less than 7min 20sec. For reference, the twin-turbo 997 GT2 RS managed a time of 7min 18sec.
Despite this new car being faster on circuit than the previous GT3, Preuninger also reckons it’s more comfortable on the road. Weight is more or less unchanged, at 1413kg, although the manual ’box saves 17kg compared to PDK. Porsche quotes a 3.9sec 0-62mph time for the manual car and 3.4sec with PDK, with top speeds of 198mph and 197mph respectively.
The UK list price is £111,802, with the first cars set to arrive early in the summer. If you can find a dealer willing to sell you one, you’ll once again have the choice between Comfort and Clubsport specifications. In light of the countless improvements and refinements Porsche has made to this new 911 GT3, Preuninger’s answer to my question is as emphatic as it is predictable. ‘Absolutely,’ he says. ‘This is the best GT3 to date, no doubt about it.’