Thursday, July 28, 2016

Porsche 911 GT3 RS Tech Dive: Why It’s the Best 911 of Them All

-The Porsche 911 GT3 RS is, in our opinion, the king of the vast 911 lineup—although the Turbo S is more expensive to start—and second-in-command to the now-discontinued 918 Spyder supercar in the modern Porsche hierarchy. Needless to say, when we finally pried ourselves out of the driver's seat of this example to capture photos, it was difficult to put down the camera. But it was worth the down time to capture the collection of spectacular details that follow. This particular car rang in at $192,420 and was equipped with all the weight-saving options and almost none of the luxury frippery—items like a leather interior, the front-axle lift system, or even air conditioning and a radio were all absent. It's the build combination most true to the RS lineage.-Porsche's carbon-ceramic brakes—Porsche Ceramic Composite Brake (PCCB), in marketing speak—are a $9210 option on the GT3 RS. Now in their third generation of development, the PCCB rotors are made of silicon carbide reinforced with carbon-fiber chips. They are slightly larger than the standard cast-iron units at 16.1 x 1.4 inches in front and 15.4 x 1.3 inches in the rear, and are clamped by massive fixed aluminum calipers (six pistons front and four pistons rear). And in the case of the GT3 RS (as well as the GT3 and Cayman GT4), the brakes also come with more aggressive Pagid brake pads; the whole system is utterly confidence inspiring and indefatigable.-No matter how large the brakes, they'll succumb to fade without proper cooling. Pictured here are the GT3 RS's large ducts channeling cooling air to the rear brakes, one of the reasons that the RS's braking stayed consistent lap after lap during our track test, unlike its 911 Turbo S sibling, whose brakes go soft after a couple laps.-The sounds that emanate from these twin pipes are otherworldly; the GT3 RS's 8800-rpm wail is one of the best-sounding—and loudest—production-car noises extant. The car sings through a 9.9-pound titanium exhaust, which saves 6.6 pounds over the GT3's steel muffler. Our relentless high-rpm excursions no doubt helped to cultivate the dramatic purple coloring.-Notice the massive amount of height adjustability in the rear shocks; our car is set to its beginning third or so of travel, even though the rear tires were tucked up into the rear bodywork and were occasionally rubbing during extreme track driving.-In addition to front and rear ride-height and anti-roll bar adjustability, the GT3 RS's front shock towers (shown here) allow for camber adjustments up to roughly negative 1.5 degrees. But maybe it could use a little more: Although the GT3 RS cornered at a heady 1.08 g on our skidpad, the latest Corvette Grand Sport, at 1.18 g, comfortably topped that. The Corvette's track-alignment settings call for more negative camber, at 2.0 degrees.-As in the GT3, this harder-core RS variant has a small actuator (shown in the center of the photo) to steer the rear wheels up to 1.5 degrees in either direction. Below 31 mph, it turns the rears in the opposite direction of the fronts, which shortens the turning diameter, and above 50 mph it steers them in the same direction as the front tires. It's been expertly dialed in, because the steering is exemplary and never feels in any way artificial or non-linear.-The quickest way around Virginia International Raceway—yes, we had the car at this year's Lightning Lap shootout—is to go bounding over the curbs. But that didn't happen without some collateral damage to the GT3 RS's rear fender wells, shown here.-Nearly all of the underbody is covered to smooth airflow—Porsche claims that the GT3 RS achieves the identical coefficient of drag (0.34) as the GT3 despite having double the downforce. Note the exceptions in the form of the strategic NACA ducts for specific cooling needs.-This nifty Porsche tool threads onto the hub to ensure that the wheel comes off and goes back on straight and true because, as the Porsche technician was quick to remind us, -One of the top priorities of the GT3 RS development team was to shoehorn the 20-inch front and 21-inch rear Michelin Pilot Sport Cup 2 tires from the 918 Spyder supercar into the 911, yielding a 20-percent-larger contact patch than on the GT3. Although the wheels are made of forged aluminum instead of the 918's (optional) magnesium, they were surprisingly wieldy, which is probably a large contributor to the GT3 RS's impressively forgiving ride quality over small road imperfections.-Archimedes no doubt would have gotten a kick out of Porsche's center-lock wheels, with their stratospheric 443 lb-ft tightening torque requirement. (The GT3 RS's 4.0-liter falls more than 100 lb-ft short of having sufficient twist to secure the car's lugs at its 6250-rpm peak.) But the Porsche technician actually made the task—which involves torquing, loosening, and then re-tightening the lugs—look easy with this extraordinarily long torque wrench.-Expensive, impractical, fussy, and incredibly cool: Porsche's center-lock wheels.-Although the GT3 RS's defining characteristic is its wailing, 500-hp flat-six, it's tough to see any visual evidence of its existence from either above or below. Upsized from the GT3's 3.8 liters to 4.0 liters in the RS by way of a 4-mm stroke increase, the RS version has fortified pistons and titanium connecting rods, and its crankshaft uses a special tempered steel straight from Porsche's 919 Hybrid LMP1 race car: The steel is melted and re-melted multiple times in a vacuum to achieve its ultra-high (and no doubt mega-expensive) purity.-With the underbody panels removed, we can finally catch a glimpse of Porsche's highly evolved, flat-six masterpiece.-The GT3 RS is available only with Porsche's dual-clutch automatic, called PDK. Although we have a Pavlovian response to the thought of a manual paired with this glorious engine—as it is in the new 911 R—the PDK gearbox works terrifically in the GT3 RS. It's smooth when driven gently and lightning-quick when asked to be. On track and in Sport mode, PDK is so prescient that no paddle inputs are required to always be in the optimum gear. Which is why, love of manuals or no, we can agree with Porsche on one thing: PDK definitely makes for quicker lap times. ---This version of PDK doesn't have -These carbon-fiber-shell bucket seats are the best sport seats in the business. They have enough lateral support to make them useful on the track, but are generous enough to allow those with a physique larger than that of a professional racer—that's essentially everyone—to drive long distances in comfort. The backrest is fixed, but we had no qualms with its angle; adjustments include manual fore and aft and a power height. Clambering over their rigid, high-walled sides when getting in is well worth it every time.-Ostensibly a trickle-down innovation from racing, Porsche's new pit-speed mode—essentially a second cruise-control function that will limit speed to a selectable set point up to 55 mph—seems gimmicky and proved less-than-intuitive to use, as it requires switching back and forth between traditional cruise control and pit-speed cruise.-One of the very rare no-cost options in Porsche's vast catalogue is the GT3 RS's stereo/infotainment delete. Ditching the 7.0-inch touchscreen and its ancillaries saves 17 pounds.-Switching out the interior door handles for pull loops made of seatbelt material is a regular Porsche GT trick. In this case, the deletion of the handles, along with the modified door panels save nearly a pound. (A whole pound!)-The other no-cost light-weighting opportunity is to eliminate the air conditioning system, saving 26 pounds, although after a 700-mile road trip in 90-degree heat, it's not one we'd necessarily recommend. Running the fan seemed to bring in air that was always substantially warmer than the ambient temperature, and we also had trouble keeping the windows from fogging when it was raining.-The driver's delight is directly proportional to the proximity of the tachometer needle to its monstrous 8800-rpm limit. Factoid: To have the gauge faces rendered in white, as on our test car, is an $860 option. (Red is also available for the same price.)-Sticker versions of the Porsche crest up front and the model name at the back are an RS tradition. This is done not so much for weight savings, says Porsche, but as a tie-in with its (and, really, any maker's) race cars.-The front splitter and the fender vents (see next slide) are the main contributors to the GT3 RS's additional front downforce. But this photo also shows our car's indulgent, $3715 headlights: swiveling LED lamps with Porsche's -These gaping vents in the top of the front fenders allow high-pressure air to exit, and are thus a significant enabler to front downforce, which is a claimed 267 pounds at 186 mph. The fact that these unique fenders are made of carbon fiber saves five pounds versus the aluminum pieces on other 911s.-Working in tandem with the dramatic ducktail shape of the carbon-fiber engine cover, the massive carbon-fiber rear wing—which stands just over five feet off of the ground—adds 494 pounds of downforce at 186 mph in the most aggressive of its three adjustable positions. Overall, the GT3 RS generates three times as much downforce as the GT3, and roughly 80 percent of what the GT3 Cup racer makes.-Hybrids and EVs aren't the only automotive recipients of lithium-ion batteries, proven by this $2300 Samsung option that saves 30 pounds. However, at 40 amp-hours, the energy capacity of this lithium-ion unit is just over half that of the standard, 70 amp-hour nickel-metal-hydride battery. It's also not effective below temperatures of 14 degrees Fahrenheit. A GT3 RS with this option actually comes with both batteries, so the owner can swap between them to enable cold-weather driving if desired.-Instead of the typical lug wrench, the GT3 RS comes with this hefty socket used to remove the single-lug wheels. It's tucked out of the way under a plastic cover in the frunk (front trunk) area—the torque wrench to budge the wheels from or to the specified 443 lb-ft is not included. Sure, it adds noncritical weight, but it beats the odds that a roadside-assistance service will have one, and also saves the $300 to purchase one separately.-A frunklid made of carbon fiber instead of aluminum saves 3.3 pounds. It's also one of the RS's few material upgrades that are readily viewable, and it substantially enhances the front trunklid's visual appeal when open.-Although it doesn't look like much, this is the automotive world's first production magnesium roof. Porsche claims that it's 24-percent lighter than an equivalent carbon-fiber part—that's 1.5 pounds—not because magnesium is inherently lighter than carbon fiber, but due to the additional weight added in surface films and paint coats to smooth out the inherently rougher surface of a carbon-fiber panel. Also fascinating is the complex supply chain: The magnesium is strip cast and then warm-rolled down to a thickness of 1.1 mm at a supplier in Korea, where it is then cut into a roof-sized chunk. This is then shipped to another supplier in Canada, which shapes it to the correct curvature at roughly 800 degrees F. The magnesium panel then gets a U.S. passport stamp, where it receives a plasma oxidation coating. Then, it's off to Germany, where it's finally bolted and bonded to the GT3 RS's roof frame and painted along with the rest of the car.-Minimizing the tire-to-wheel gap is already a Porsche strong suit, but the GT3 RS goes a step further with its monster 21-inch rear tires, where they're tucked up inside the fender. The edges of the fenders on this car were already rolled for clearance purposes and, as seen earlier, the tires were occasionally rubbing during max-attack laps at VIR.-Since the GT3 RS employs the wide bodywork from the Turbo—the RS's track is increased by 1.8 inches in front, and 1.1 inches in the rear versus the GT3—Porsche had to figure out what to do with those gaping fender vents, which, in the Turbo, feed intercoolers. So the GT3 RS's intake plumbing was revised so that it's now the only 911 to inhale through the side intakes. (All the others breathe through the top of the engine cover.) Upsides include both enhanced intake roar and a claimed 10-hp boost over the rated 500 figure at high speeds from the ram-air effect.--

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