R&T April 08 will have an article called Evil Twins detailing pairs of cars including the 997S vs 997 GT3RS. Kind of fun.

Data Sheet


I think they wrote the lap times backwards at the beginning of the article...

From R&T website:
LAP TIMES:

Carrera S: 1:33.14 sec
GT3 RS: 1:37.09 sec

The Porsche 911 Carrera S and its evil twin, the GT3 RS, share the same famed rear-engine 911 profile. The GT3 RS stands slightly wider and lower, and features a lower lip spoiler up front and a pronounced wing on the rear deck. Probably the bright M&M-green paint job is what really sets the RS apart from the Carrera S.

But the devil is always in the details.

If you haven't checked the engine specs listed nearby, you'd know — with the first twist of the ignition key — that the Carrera S and the GT3 RS do not share the same powerplant. The S has a strong, but muted engine note. The RS spins to life with authority and makes its presence known, thanks to a thundering crackle through the exhaust. The road-going 911 is equipped with a 3.8-liter flat-6 rated at 355 bhp and 295 lb.-ft. of torque. And the more potent twin is armed with a different, race-bred 3.6-liter flat-6 capable of pumping out 415 bhp and 300 lb.-ft. of torque. Moreover, the RS's different engine fitment also calls for a 6-speed manual with slightly taller gearing in the lower ratios to take advantage of the car's higher 8400-rpm redline.

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To turn the Carrera S into a worthy track racer, the GT3 RS takes the same basic front MacPherson strut and rear multilink suspension setup and firms it up with more aggressive springs and shocks. The Porsche Active Suspension Management (PASM) can already change the RS's ride character on the fly with a push of button in the cockpit. But to allow additional fine-tuning of the suspension on the track, front and rear struts have external threads and spring perches for ride-height adjustments. Further, at the rear are unique split track-control arms; metal bushings replace rubber ones for more precise wheel location at speed. Both front and rear anti-roll bars are also adjustable.

The GT3 RS is about 80 lb. lighter, thanks in part to deleting the rear seats and replacing the spare tire with a small electric air compressor and tire sealant. The Porsche Ceramic Composite Brakes (PCCBs) on the RS are 50 percent lighter than the stock rotors, reducing unsprung mass by 34.4 lb. The combination of weight savings and more horsepower equates to better acceleration numbers.

Zero to 60 mph in the RS is clocked at 3.9 sec., which is 0.2 sec. faster than the Carrera S. But as the speed builds the high-revving RS engine pulls more aggressively, thanks to a variable-volume intake system that switches over at 6350 rpm. The car pushes past the 100-mph mark with a 1.3-sec. advantage. The quarter-mile is covered in 12.1 sec. at 116.6 mph, 0.5 sec. and almost 5 mph faster than the Carrera S. In the handling department, the RS again edges out the stock S with 1.04g on the skidpad, and travels more than 3 mph faster through the slalom course. In brake tests, the GT3 RS actually needed a few feet longer to stop from 60 and 80 mph. This is perhaps due to the PCCBs not reaching their most effective operating temperature.

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Of course, warming up the brakes is never a problem at Willow Springs. Right after Millen lapped the GT3 RS nearly 4 sec. quicker than the Carrera S, he noted: "The brakes are great. It got better as the laps went on." He is able to drive deeper than the Carrera S into the corners. The data showed that significant time was saved here in Turns 1, 2 and 3.

On the GT3 RS through Turn 2, Millen comments: "If you don't get into the corner quite aggressive enough, you are going to feel a little bit of understeer. With progressive throttle, the car will turn without breaking the rear away. However, too aggressive on the gas and the rear will come around in low-speed corners." To fight understeer in long corners, Millen says, "Give it more throttle, and you actually make the car more neutral."

Around Turns 8 and 9, "The Carrera feels nervous all the way through here. There is lot more movement in the suspension. The car moves laterally and vertically." Millen notes, "In the RS you can just feel the extra downforce. It is much more stable through the bumps thanks to terrific shock control. The rear is completely planted. In fact, coming out to the front straight, you can actually slide off the corner with the rear wheels spinning a bit."

Overall, Millen concludes: "The two Porsches are quite different in many ways. The GT3 RS is so well-balanced. Taking advantage of the engine's higher revs is how you are going to get fast lap times. The Carrera S is limited by its understeer and its engine's lower rev limit. And I find it's better to use a higher gear in corners because it has such a broad powerband and I don't need to be at the top of the revs."

Slideshow >>

The Porsche twins' divergent track dynamics also translate directly to their street-going nature. On the road, the Carrera is able to offer a great balance between sporty handling and supple ride quality. Kott comments: "The 911 S has a firm ride on the street, but its ride quality is very livable even for long trips. Steering feels wonderfully alive...every pavement seam and ripple feeds through the wheels into your hands. It feels precise, quick, yet not darty."

Climb aboard the RS and you'll immediately understand why track cars are not meant to be driven on the street. Editor, R&T Specials, Andy Bornhop writes: "On the road the RS demands some sacrifice. It's loud inside and has a very firm ride. And you have to pick your driveways carefully (and proceed slowly) to avoid scraping the chin spoiler."

Even though the Carrera S and the GT3 RS are born of the same 911 DNA, these two cars couldn't be more different in their intended purpose. The Carrera is perfect for the road. The RS is perfect for the track. In this battle of evil twins, is it better to be "the master of one" or the "jack of all trades"? So take your pick. If the racetrack is where you want to live, the $50,000 jump in price from the Carrera S to a GT3 RS may be worth it. But if you are like most of us, where our day job calls for driving mostly on public roads, go for the Carrera S. You'll feel more comfortable, and occasionally you can still satisfy that racing itch and squeeze in a few weekend track days.

 

Interesting read. Thanks for the post

 

Why would they compare these two cars?

Thanks for sharing!!!

 

Here is the video.... The point of the comparisons were comparing road going versions to the track versions (GT3RS vs C2S/Viper vs ACR/Superleggera vs Spyder)
http://www.roadandtrack.com/video/in...tid=1425900017

 

Great read. Thanks for the vid Martin.

 

Very Interesting!!

 

you mean RS is 33.14 sec and CS is 37.09 sec right?

 

good read! thanks for posting

 

Great read. Thanks for posting!

 

I'm assuming so much....I actually pointed that out before the article quote from the R&T site. I think they just transcribed it backwards.