A staggeringly responsive track special and a significant leap in technology compared with its 997 RS predecessor, here’s all you need to know about the 991.1 GT3 RS

Written by Kieron Fennelly

HISTORY & TECH

The RS moniker on Porsche dates from the 1950s, but the first Porsche RS that most think of is the celebrated Carrera 2.7 RS of 1972/3, built to qualify Porsche for Group 3 racing. Until the end of the air-cooled era, the RS remained the special race version, mildly tuned and lightened, and with reduced equipment and hardened suspension.

The advent of water-cooling in 1997 dictated a different approach. Production limitations and homologation requirements ruled out lightening, and the stiffer-chassis 996.1 GT3 on which the RS models would be based was 50kg heavier than the Carrera. The 996 GT3 RS of 2003, the inspiration of the Motorsport department’s Andreas Preuninger, was an attempt to make a lighter, less-compromised GT3 track car and provide a homologation basis for the competition RSR.

The 997.1 GT3 RS presented in 2006 effectively dressed the GT3 in race gear, while the face-lift car of 2008 had more developed aerodynamic aids and used the 3.8-litre flat six that Porsche had been campaigning in the 996 RSR. It was some 25kg lighter than its GT3 equivalent.

After a hiatus of four years, the 991.1 GT3 RS represented quite an advance. Using the 991 Turbo body, the new RS was bigger than its predecessor. With more complex ducting around its rear flanks, a rear spoiler and vents in the front wings, the 991’s downforce figure was twice that of the 997. Indeed, the 991 RS represented Porsche’s most sophisticated aerodynamic package yet seen on a (nominally) road-going 911. Making extensive use of carbon fibre, in the weight-saving stakes the RS also went one better than its sister GT3 by having a magnesium rather than aluminium roof panel. Even more impressive was the engine. Gone was the long-serving ‘Mezger’, superseded by a bespoke 4.0-litre flat six. With a 12.9:1 compression ratio, for homologation purposes it developed 500ps at 8,800rpm, though in fact nearer 515ps, revealed Preuninger. For a production engine this was an amazingly high-revving unit; however, after the crankshaft failures of the even-higher revving 3.8 of the 991.1 GT3 RS, Porsche was taking no chances. Besides bespoke titanium con rods and followers, and its own dry sump oil system, the crowning glory of the RS’s 4.0-litre powerplant was the 919-derived crankshaft. This was an expensive component made from a special steel alloy, remelted several times to give lasting resilience.