The 996 GT3 RS of 2003 was the first car worked on by Andreas Preuninger, now the legendary Director of GT cars at Porsche. Back then its 7 minutes 48 seconds lap time set by Walter Röhrl was pretty rapid.
By 2011 the 997 GT3 RS 4.0 had reduced that time to 7 minutes 27 seconds, 6.0 seconds faster than the Carrera GT of 2004. Then in 2015, the first generation 991 GT3 RS recorded 7 minutes 20 seconds.
The 6 minutes 56.4 seconds lap clocked in April this year by Porsche works racer and test driver, Kevin Estre shows a massive leap in performance of over 24 seconds in just three years.
“Our computer simulations gave us expectations of around a 6 minutes 58 seconds lap at best,” recalls Uwe Braun, Manager Motorsport GT Line. We had a small team of five engineers, five mechanics and two drivers at the ‘Ring. Lars Kern, our works driver who set the GT2 RS record last year did two laps at 6 minutes 69.3 seconds and 6 minutes 57.5 seconds, then Kevin went out and did a 6 minutes 57.7 seconds first lap followed by his record breaking 6 minutes 56.4 seconds lap.
These numbers were prominent in my mind as I ventured onto the Nürburgring GP Circuit, a modern, quite technical track that is far less forbidding than the Nordschleife next door that is famously used by the industry to benchmark fast cars.
The 991.2 generation GT3 RS weighs 1,420kg and its new aero package generates 40% more downforce that its 2015 predecessor. In raw numbers this translates to 450kg of downforce at 300km/h, and 486kg at the 312km/h top speed, with a front/rear aero balance of 30 / 70%.
The 3,996cc naturally aspirated flat-six motor develops 520hp at 8,250rpm with the rev limiter set at 9,000rpm. Peak torque is 470Nm at 6,000rpm, but as the curve is actually quite beefy below that, you can go very quickly on the road without exceeding 6,000rpm.
“The basic engine is identical to the standard GT3,” said Thomas Mader, Project Manager for GT Road Car Engines. “And rather than having different engines for the road and race cars, we set out to design one 4.0 litre flat-six engine family to fulfil both roles. Thus, the same basic motor powers our GT3 and GT3 RS road cars as well as the GT3 R, GT3 RSR, and GT3 Cup. All have 4.0 litre swept capacity apart from the Cup car, which is 3.8 litre.”
“Apart from cost saving this common basic engine establishes a genuine connection between our road and race cars, and allows us to test for durability under the harshest possible conditions,” he continued. “If it does not break during a 24 hour race, it is unlikely a customer will break it on a track day!”
Internally, only the RSR motor has pistons with two rather than three oil control rings, a feature taken from the 918 Spyder’s race derived flat-plane crank V8. “If you can control oil consumption and clearances properly then a two-ring piston is a nice thing to have as it is lighter, which contributes to lower inertia and a faster revving motor,” says Thomas.
Like their race engine counterparts the high revving engine in the GT3 and GT3 RS features solid lifters with tappet clearances set at the factory for life. The RS’s titanium exhaust system is also identical to the GT3’s apart from the two end pipes, which are of a slightly larger 98mm diameter purely for looks.
Oliver Berg, Manager GT-Product Line, and the leader of the GT3 RS project explained that the GT2 RS and GT3 RS share the same bodyshell, but where the rear wheel arch intakes direct ram air to the intercoolers of the former, they send air to the intake system of the naturally aspirated car. Slight timing changes to the variable camshafts to make full use of this extra air help the GT3 RS engine (internally known as the 9A1 MA177 variant) develop its extra 20hp and 10Nm of torque.
“This a more effective system than the previous GT3 RS models which had ram intake scoops on the engine cover lid,” he explained. “While the old system generated about 20hp more at top speed the side intakes further enhance the air velocity, so we now have an additional 25 to 30hp over the rated 520hp output at 300km/h.”
“The extra 10Nm of torque is not a peak value at any one point, but is an upwards move of the whole curve to compensate for the drag created by the greater aerodynamic downforce,” said Thomas. “The ECU mapping is also aimed at delivering even better throttle response and perceived ‘punch’ in line with the RS’s role. In this and other respects of the GT3 family philosophy the track-biased PDK-only RS sits in the opposite corner to the manual only road-biased GT3 Touring.”
A car that can blast to 100km/h in 3.2 seconds, pass 160km/h in 6.9 seconds, 200km/h in 10.6 seconds and top out at 312 km/h is very quick, but as the GT3 RS is a track biased car I was keen to get out there put it through its paces.
From my first lap of the 10 right hand and seven left hand corners that make up the 5.148km long Nürburging Grand Prix Circuit it was obvious that the new GT3 RS is a whole different ball game from both the current GT3 and the GT3 RS of 2015.
The RS is no faster than the current GT3 in a straight line as the extra power and torque are used to compensate for the greater downforce created by the new aero package. But that downforce delivers so much more speed through the bends it makes the RS significantly faster round a given circuit. You can really feel the aero working, even in medium speed bends, where the combination of larger rear wheels and tyres from the much more potent GT2 RS and the downforce makes the RS feel incredibly planted, yet very docile on the limit.
I remember taking some time to explore the limits of the 2015 GT3 RS, its transition from grip to slip not being quite as clear. Yet, despite having 40% more downforce the new car communicates better, both through its steering and your seat of the pants. I partly attribute this to the latest generation of Michelin Pilot Cup 2 N1 tyres, which are not only stickier and able to hold their grip levels much longer under hard use, but also subjectively feel more progressive on the bald limit.
Using the full might of the huge PCCB stoppers from the faster and heavier 918 Spyder, the new GT3 RS also has tremendous braking power. You can really stand on these anchors lap after lap with no noticeable deterioration in either braking distances or the very good pedal feel.
You will notice that the carbon fibre bonnet features the same NACA ducts that send cooling ram air through channels in the inner wings to the big brakes on the GT2 RS.
However, where the GT2’s front lower suspension arms feature an additional bolt-on deflector to further increase airflow to the brakes, this is absent from the GT3 RS. This results in better aerodynamic characteristics that help keep the airflow under the car cleaner as it heads towards the rear diffuser that enhances rear downforce to the tune of 30kg at top speed.
The raised front wheel arch vents, which are shared with the GT2 RS come from the Cup car. The front splitter with its raised centre section and aero indents in the side is from the RSR, the diffuser is like the GT3 R, and the NACA ducts are Cup car, where they are used for driver rather than brake cooling. There is real racing technology in the new GT3 RS.
As it has to meet safety regulations for the road the big carbon fibre rear wing is no wider than before and there is no Gurney flap. Meanwhile, the big end plates act as boundary layer fences to stop drag inducing air spillage to the side. The new RS has a Cd of 0.36 with its wing in its cleanest form and 0.39 when set for maximum attack. Where the wing on the 2015 GT3 RS had three positions; 0, 2 and 4 degrees the new RS has four; -1, 1, 3 and 5 degrees.
While the GT3 is a good track weapon, the RS moves even more towards the race car world with solid bushes in its suspension arms and steering tie rods, and various lightweight components that all make for a driving experience closer to a genuine competition machine.
On paper the spring and damper rates of 100N/m in front and 160N/m at the rear are pretty wild. They are the same rates as on the GT2 RS and not far off those of the racecar. Getting the car to ride well enough for the road took a lot of work and the damper settings that tame the firm spring rates were developed over many miles of testing and calibration.
Trail brake deep into slow and medium bands and your reward is a race car like behaviour with the immense front-end grip anchoring the car nicely as the rear steering helps it rotate seamlessly towards the apex. Thanks to this exquisite balance you can get back on the throttle sooner than you initially think, using the fabulous traction conferred by having the engine over the rear wheels for the best possible exit.
The electric steering is superb, and at the other end of the car you really don’t realise that the rear wheel steering is there, so progressively and seamlessly does it help you turn into a bend. In fact it has got to the point where you can no longer tell that the GT3 RS has its engine in the rear, except of course when that extra weight over the driven wheels helps you exit a bend faster than any front engine rear drive or mid-engine car can manage.
Throttle response of the naturally aspirated 4.0 litre flat six is simply electric. The right pedal is so well calibrated it gives you the impression that you can dial in power in 100rpm increments, the razor sharp engine note a tell tale that supports this.
Seeing the rev counter needle soar towards the 9,000rpm limiter in each gear in the periphery of your vision is slightly surreal, its climb matched by a soundtrack akin to a deep buzz saw rising in octaves to match each 1,000rpm passed on the rev counter dial.