Wednesday, November 14, 2007

2008 Porsche GT2 Test Drive: L.A. Auto Show Preview

You’re looking at the first Porsche 911 that will top 200 mph right off the showroom floor. It goes 204 mph to be exact. That’s faster than the regular Turbo and much quicker than the GT3 version homologated for racing. And it bristles with some of Porsche’s best technology. It will go from 0 to 62 mph in 3.6 seconds and hit 100 mph in less than 7.5 seconds. We kept the hammer down on this bad boy all the way to 170 mph on a track. Yeah, this is one massively fun ride.

The third generation GT2 ups the power of the Turbo’s twin-turbocharged 3.6-liter engine from 480 to 530 hp, with 505 ft.-lb. of torque from 2200 to 4500 rpm. The engine uses two variable-geometry turbochargers and Porsche’s VarioCam variable valve timing and lift hardware and software, plus a free-flowing exhaust system that’s made of expensive titanium alloys from one end to the other. That not only enables the engine to make more power but also lightens the rear end of the car by quite a few pounds.

Although it’s a twin-turbo engine, the 3.6-liter mill is not just a juiced version of the existing engine. The entire intake system between the two turbos and the intake valves has been changed to take advantage of the sinusoidal waves that bounce back and forth in the intake tract, a system that Porsche Motorsports engineers call an “expansion” intake system. By enlarging the castings, passages and ports to capitalize onthese waves, says Karsten Schebsdat, the GT2 project engineer, the engine can operate at lower temperatures, use more spark advance and less fuel, and offer more all-around drivability. And because it’s a Porsche, it helps make more power too.

Lightweighting is one of the keys to this car’s high speed and pinpoint-accurate handling. The GT2 does not use all-wheel drive like the 911 Turbo, saving considerable weight on the nose of the car. Porsche uses special Alcantara-clad carbon-fiber sport bucket seats that are 40 pounds lighter than the standard power units. Unlike most 911s, there’s no room for the kiddies in back—just two carpeted panels, with provisions for roll-bar installation. A unique sound insulation package removes some weight too, along with the lighter suspension components front and rear. In the end, the GT2 comes in 320 pounds lighter than the Turbo. The Porsche Ceramic Composite Brakes, or PCCB system, normally an $8000 option on other 911 models, is standard on the GT2. They’re not only hugely powerful but also over an inch larger than the 13.8-in. brakes on the Turbo and GT3. And those PCCBs are a full 40 pounds lighter than the conventional steel brakes.

The GT2’s outer skin is a combination of the existing Carrera 4 and Turbo bodies, some 8 percent stiffer in torsion and 40 percent stiffer in bending than the previous GT2 body. It carries not one, not two, but three large radiators in the nose, with massive openings to flow as much cooling air as possible through them. And, because it uses the four-wheel-drive bodywork without the drive system itself, there’s room up front for a hefty 23.8-gal. fuel tank.

Like the GT3, the GT2 has a small grille of sorts above the bumper in the nose. That grille is designed to simultaneously exhaust hot air from the front radiator and provide downforce. At the rear, the GT2 carries a fixed biplane spoiler that, for the first time, incorporates a pair of engine air intakes. The slots in the fenders exhaust hot air from the engine’s intercoolers, which also provides some additional aerodynamics. Those body mods, plus the racing-style undertray, help the GT2 produce more aerodynamic downforce than any 911 in the model’s 44-year history. And yet the GT2 slices through the air with a drag coefficient of only 0.32.

Because the GT2 is like a turbocharged version of the naturally aspirated GT3, it’s fully homologated for racing in many countries around the world. And that includes club events and track days here in the States. The GT2 comes with a slightly different initial setup than the more-aggressive-handling GT3. It has a lower roll center at the front and a higher roll center at the rear for smoother left-right transitions versus the racier GT3. But it’s all adjustable.

The GT2 uses a very sophisticated suspension system that features a wide range of adjustments for ride height, spring rate, caster, camber and toe-in that can be done using simple tools and adjusting cams and shims. The GT2 uses a strut front suspension and a multilink rear suspension with adjustable coil springs and stabilizer bars on both ends. The ride height can be raised or lowered over a range of just over 2-inches. The GT2 comes with only P325/30ZR-19 Michelin Sport Cup high-performance tires mounted on lightweight alloy wheels. These tires are completely performance biased, so don’t expect them to last past 10,000 miles.

This new-generation GT2 is the first to use Porsche’s Active Suspension Management (PASM) and PSM traction and stability control, with separate shutoff buttons for each system for track work. The previous model had no electronic intervention. The GT2 even comes with a new Launch Assist feature. The launch system comes into play when all other systems are engaged; the engine is making at least .9 bar (13.2 pounds per square inch) of boost; and the revs are high enough. It allows for a completely clean getaway from a stoplight or out of the pit lane on a racetrack. The GT2 also packs automatic brake differential, automatic slip control, engine drag control, and a limited-slip differential borrowed from the Carrera GT, all operated by the traction control computer.

Although it has no back seat, the GT2 is hardly a stripper, with options like navigation, the Sport Chrono onboard timing system, a six-disc CD changer, and a 325-watt Bose sound system with 13 speakers and a seven-channel digital amplifier.

The 911 GT2 qualifies as environmentally friendly, sort of. It meets the LEV II emissions rating so there’s no gas-guzzler tax. Porsche will build only 1500 911 GT2s for the entire world over the next six months or so. Only 200 examples of this $191,700 supercar will come to North America. We’ll take a black one. —Jim McCraw

2008 Dodge Viper SRT-10 ACR: L.A. Auto Show Preview

Track-day junkies can finally get their hands on a street-legal racing version of the Viper to drive to the course—because railering is just so unccool. The Viper SRT10 ACR’s prodigiously powerful 600-hp engine remains unchanged from the standard, but the suspension is hardened up to improve the Viper’s already impeccable racetrack manners.

StopTech provides lightweight, two-piece vented rotors for sustained racetrack braking performance. The exterior package includes hinged front splitters, an adjustable rear wing and a sporty hood stripe. New wheels, featuring track-ready Michelin Sport Pilot tires, trim a good 40 pounds from the Viper. The Hard Core package replaces most of the upholstery in the interior with carbon fiber and substitutes a lap timer for the radio, saving 40 more pounds. Dodge says the ACR will be available late next spring for under $100,000—but not very far under, we’re guessing. —Mike Allen

2009 Chevrolet Silverado Hybrid: L.A. Auto Show Preview

LOS ANGELES — When it hits the market in late 2008, Chevy’s new Silverado Hybrid is expected to be the most fuel-efficient full-size pickup yet—an impressive distinction for the domestic workhorse. Working in conjunction with 300-volt nickel metal hydride batteries that sit beneath the rear seats, the 6.0-liter V8 powerplant is capable of operating on four cylinders for economy, or shutting off completely at speeds of up to 30 mph.

The two-mode hybrid system uses regenerative braking for fuel economy, and will be capable of operation while towing up to 6100 pounds. An electrically variable transmission (EVT) rounds out the powertrain setup, enhancing seamless delivery of power for either 2WD or 4WD crew cab models.

The Silverado Hybrid should also ride quietly, thanks to low-rolling resistance tires, electrically powered HVAC and steering systems, and internal fans designed to cool the NiMH batteries. Its Z85 suspension is specially tuned for hybrid duty, and a new hydraulic body mount smooths out road surface irregularities. Long-haul drivers might benefit less from the hybrid system, but should appreciate the 26-gallon fuel tank, which enables a theoretical cruising range of more than 500 miles. Underneath its imposing exterior proportions, the 2009 Chevrolet Silverado Hybrid promises to offer a unique combination of fuel economy, rugged utility and cruising comfort. —Basem Wasef



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