Porsche 991.1 GT3 RS buyer's guide

The 997 GT3 RS 4.0 was an incredibly tough act to follow, but the 991.1 took that ball and ran with it. While arguably losing some of the analogue character of the older car, it raised the bar in terms of point-to-point performance – whether on a road or track.

Larger bores stretch the engine capacity from 3.8 litres in the contemporary GT3 to 4.0 litres here. The RS also gained spikier cams, new pistons and valve springs, plus a titanium exhaust. The crankshaft is made from the same lightweight steel alloy used in the 919 Le Mans racer (Andreas Preuninger called it “Star Trek steel”). Peak power of 500hp arrives at 8,250rpm.

Controversially, the 991.1 GT3 RS wasn’t available with three pedals (a manual shifter was later offered on the 991.2 GT3), but the seven-speed PDK ’box is incredibly quick and precise. It also allows for full-bore launch control starts, blasting the RS to 62mph in 3.3sec and 124mph in 10.9sec.

The Rennsport uses the widebody and vented rear wings of the 911 Turbo, with a magnesium roof and many panels made from carbon fibre-reinforced plastic (CFRP). The aero package is comprehensive, including a flat undertray, slash-cut vents in the front wheelarches and a full-width rear wing. Overall downforce is more than twice that generated by the 997 GT3 RS 4.0.

In terms of chassis tech, the most notable advance is rear-axle steering, which makes the car more stable when cornering. The GT3 RS rides on 20-inch centre-lock front wheels, with huge 21-inch rims at the rear. Carbon-ceramic brakes and roll cage were optional, and buyers could also specify a smaller lithium-ion battery to save weight. 

Unlike most cars, evidence of track use shouldn’t be a barrier to buying a GT3 RS. However, it’s vital to ensure the car has been properly maintained, with regular oil changes to keep the naturally aspirated flat-six healthy. Checking the oil level is done via the onboard computer, rather than using a physical dipstick. Check out the RPM Technik guide to the process here. 

Ollie Preston, technical director at RPM Technik, says the 4.0-litre engines are very robust – and not troubled by the connecting rod issue that afflicted the 991.1 GT3. “The main issue we find is that the geometry is out, and having the right setup is very important,” he explains. “The rear-axle steering is linked to the PASM and stability systems, so it must be calibrated by a specialist – otherwise you may end up with odd handling characteristics.” 

Indeed, Greig’s advice is to always have a car inspected by a Porsche specialist before you buy. “There may be crash damage from track days, and the aerodynamic undertrays must be removed to examine the chassis properly.” With the bonnet, front wings, engine lid and rear spoiler all made from CFRP, there’s no way to repair a GT3 RS on the cheap…

Other issues may include cracks in the carbon-ceramic brake discs, a worn Plexiglass rear screen and gravel in the air intakes from a track-day ‘off’. Buy the best you can, as even with 5,000 cars made (more than triple the total for the 997.2 GT3 RS), this sought-after 911 is unlikely to depreciate.

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The options list for the 991.1 GT3 RS was relatively short by Porsche standards, perhaps reflecting the Rennsport ‘less is more’ ethos. If you’re in the market for one, the following extras are worth considering.

Greig says this isn’t essential for road use, but it provides peace of mind and adds to the car’s resale value.

The fixed-back buckets from the 918 supercar look fantastic and are surprisingly comfortable. However, the standard folding seats are more practical if you want to carry luggage in the back.

These are better for track days than the standard steel discs, although RPM Technik now offers Surface Transform ceramic discs as an aftermarket upgrade. 

Equally, as with any Porsche, this is a worthwhile extra if you plan to tackle some track days.

The air conditioning and PCM media system could be deleted as a no-cost option to save a few kilos. Can you really live without them?

Ollie considers this kit the only essential upgrade for the 991.1 GT3 RS. “It really transforms the car, with better compliance on the road and improved high-speed stability on the track.”

Years produced: 2015-2017

Engine: Flat-six, 3,996cc, naturally aspirated

Power: 500hp @ 8,250rpm

Torque: 460Nm @ 6,250rpm

Compression ratio: 12.9:1

Transmission: 7-speed PDK auto

Front: MacPherson struts with PASM

Rear: Multi-link with PASM and rear-axle steering

Front: 9.5x20-inch; 265/35/ZR20

Rear: 12.5x21-inch; 325/30/ZR21

Front: 380mm discs

Rear: 380mm discs

Length: 4,545mm

Width: 1,880mm

Weight: 1,420kg 

0-62mph: 3.3 sec 

Top speed: 193mph