G8 Got X-Ceptional Performance?

If you've ever wondered how Pontiac would equip a "'roid-raged" G8, you're about to get your answer. On the heels of the first G8s hitting American showroom floors, came Pontiac's announcement that the G8 GXP, the "flagship of its GXP series," would be added to the model line for '09.

Set to debut in late 2008, the G8 GXP promises more power than the G8 GT thanks to a 402hp LS3 engine. Not available in the GT, an optional six-speed manual transmission will be offered, as will steeper rear gearing (3.27 auto and 3.70 manual), and a standard limited-slip differential. Larger 14-inch front brakes and 19x8-inch polished aluminum wheels with P245/40R19 tires are part of the package as well.

Jim Bunnell, Buick-Pontiac-GMC general manager, states, "More than just raw power, the GXP delivers the sophisticated, yet exciting, driving experience that enthusiasts expect in a car costing far more."

According to Pontiac, the suspension is tuned for "the highest performance in the G8 family," and, "The GXP's ride and handling was developed and validated on racetracks and highways around the world, including the famed Nrburgring racing circuit." This is the longhand version of saying it should handle very well.

To let the world know that this is a very special G8, there are also subtle front and rear fascia changes. GXP identification can be seen on the front fenders, decklid and inside, embroidered into the heated power-adjustable leather seats, which are available in Ebony or an Ebony/Red two-tone. Other standard interior features include a leather-trimmed steering wheel and gear shifter, foglamps, alloy sport pedals, a 230-watt Blaupunkt audio system and XM Satellite Radio. The exterior color palette for the GXP will be the same as the other G8 models.

Compared to the 6.0L 364-cube LS2 that was last seen in a Pontiac in the '06 GTO, the LS3 engine features larger cylinder bores to deliver 6.2 liters, and 376 cubic inches. "The block casting also has revisions and machining in the bulkheads to enhance its strength and improve bay-to-bay breathing," Pontiac states. The injectors, intake manifold and the heads flow better than the LS2 as well. "New, high-flow cylinder heads are based on the large port and valve design found on the LS7 engine and other GM L76 engines," explains Pontiac. "The larger-capacity, straighter intake port-design optimizes intake flow to the combustion chamber, an effect augmented by larger valves." Accommodation of the large ports requires offset intake rockers as well. Cam timing is revised, too. For more details on the LS3, see the specifications chart.

Why does the Vette LS3 have 430 hp and the GXP LS3 have 402 hp? "Exhaust and induction system dimensions are carryover from the G8 GT, which adds significantly higher restrictions/back pressure than on the Corvette," says Pontiac. "In addition, the MY09 GXP requires Post Oxygen Performance Diagnostics (POPD) underfloor cats that also add back-pressure, further affecting power."

To handle the torque and provide smooth and refined performance, the new optional six-speed Tremec TR6060 manual transmission features a reduction in shift throw, premium gear synchronizers, stronger gears, housing, and bellhousing, a single-piece countershaft, and machined gear teeth.

More power, plus a lower rear gear for the automatic trans than is found in the GT has Pontiac estimating a 0-60 time of 4.7 with a quarter-mile e.t of 13.0 at 108 mph for the GXP. It will all come to rest via 14-inch Brembo brakes up front that feature quad-piston calipers as opposed to the twin piston units on the 13-inch brakes of the GT.

What does all this performance cost? We don't know yet, as that info will be released when the production date gets closer, but considering the fact that Pontiac is gunning for the Charger SRT-8, the price of admission should be in that ballpark.