2006 Pontiac Grand Prix GXP Preview

The heart and soul of the new Grand Prix GTP isn't in its styling or its amenities, but once again is under the hood. The

GM's new 5.3-liter 'LS-4' V8 is a technological marvel. It's no wider than a V6 and no longer than an I-4, while featuring Displacement on Demand cylinder deactivation. (Photo: General Motors of Canada)

new engine marks the first ever production application for a small-block overhead-valve V8 in a front-wheel drive configuration. Only Pontiac's own Bonneville GXP and the Cadillac DeVille currently offer V8 power and front-wheel drive, while the outgoing Cadillac Seville and Oldsmobile Aurora previously did. While the Grand Prix GXP won't necessarily be the most powerful front-wheel drive vehicle in the world when it goes into production, eclipsed by the DeVille, it will definitely leave behind most of its imported rivals, such as the Acura TL and Nissan Maxima.

Although it's based off GM's latest fourth generation small block architecture, the 5.3-liter V8 has been redesigned for transverse (east-west) applications. Although the 'LS-4' is as long as an inline-four and as wide as a V6, several modifications including a shorter camshaft and a single-belt accessory drive system were required to fit the all-aluminum motor into the Grand Prix's engine bay. The pushrod-powered motor features high-flow cylinder heads similar to those used on the Corvette's 'LS2' V8, an electronic throttle and a new engine controller. In total, the motor produces 290 horsepower and 320 lb-ft of torque, 90 percent of which is

The GXP was introduced by Bob Lutz at this year's California International Auto Show. (Photo: General Motors of Canada)

available from 1,500 rpm to 5,200 rpm. It is capable of propelling the large, midsize GXP to 100 km/h in around six seconds.

Aside from packing a walloping punch, the new 'LS-4' motor also incorporates Displacement on Demand (DOD) technology, which made its first appearance on GM's midsize SUVs and pickups equipped with the 5.3 liter Vortec V8 engine earlier this year. By means of a sophisticated electronic controller, half of the motor's cylinders are automatically deactivated when under minimal loads to reduce the amount of fuel needed for forward movement. In light-load situations, such as highway cruising, the engine acts as a V4 with alternating cylinders on opposite banks disabled. When the sensor detects a need for more power, the engine returns with all eight cylinders firing. GM claims that this technology improves fuel economy by 12 percent.