Thanks to a clevercollection of technologies, the 5.3-litre ''small-block'' engine in the 2006 PontiacGrand Prix GXP will deliver great V-8 grunt and money-saving V-6 fuel economy,which should be attractive to people with one eye on the speedometer and oneeye on the fuel gauge.
This is, by theway, the first time in a half-century of powering endless numbers of rear-driveGM cars, the company's famous ''small-block'' V-8 will turn up in a front-drivemodel for the first time ever.
General Motors'new Gen IV 5300 5.3L V-8 (LS4) engine will power the 2006 Pontiac Grand PrixGXP next fall, and Dave Muscaro, the assistant chief engineer of small-blockV-8s for passenger cars, says it was ''engineered specifically for front-drivelayouts,'' of which GM has many.
Because itsprimary responsibility is performance, the LS4 has been tweaked to deliver 290hp and 325 lb-ft of torque, though those are both called ''estimates'' thissoon in the development process. Don't be surprised if the production model'snumbers go even higher.
Mostimpressively of all, the LS4 V-8 delivers 90 percent of that torque between1,500 and 5,200 rpm, which ought to deliver very satisfying acceleration in theGrand Prix sedan at any speed and in any situation.
Not so long ago,this kind of grunt would have been impossible because of the likelihood of thedreaded ''torque steer,'' which is auto-speak for a vehicle having so muchpower that it affects the steering system and makes the steering wheel twist. Thatapparently is not an issue in the Grand Prix GXP.
To get those V-6fuel economy levels, the 5.3-litre V-8 uses Displacement on Demand (DOD) technology,which helps the vehicle realize fuel economy gains of up to 12 percent on the Americanfuel economy test procedures.
In the realworld, this engine or any other with DOD delivers fuel economy gains invirtually every situation except those acceleration moments. It's particularlygood at using less fuel in constant speed situations, when it can turn off halfof those fuel-using cylinders.
Muscarounderscores the point that ''the engine returns to V-8 mode the instant thecontroller determines the vehicle speed or load requires additional power. Theprocess is seamless and virtually imperceptible.'' That is certainly the way itworks in GM vehicles already using DOD, and there's no reason to imagine itwon't also apply here.
''There'snothing like the satisfying feel of a V-8 engine,'' says Muscaro, ''and the5300 provides a level of performance rarely available in competitors' vehicles.But when all eight cylinders aren't required to maintain performance, DODtechnology effectively turns the engine into a more efficient V-4.''
Muscaro pointsout that the all-aluminum 5300 V-8 is the third displacement offering of theGen IV small-block, which was introduced in the 2005 Chevrolet SSR, GTO andCorvette, as well as several 2005 GM SUVs.
''The 5300 V-8shares a common architecture with these other versions,'' Muscaro says, ''includinga deep-skirt block, six-bolt cross-bolted main bearing caps, and structural oilpan, but is modified to accommodate the 'east-west' mounting position of theGrand Prix's front-wheel-drive chassis.''
To fit the''sideways'' positioning in the Grand Prix, several changes were made toshorten the engine's overall length. The crankshaft was shortened by 13 mm -- 3mm at the rear and 10 mm at the front -- and the entire accessory drive systemwas designed to reduce space. The accessories, including the water pump and thepower steering pump, are driven on a single-belt drive system, which Muscarosays is the longest drive system in a GM vehicle.
This is, by theway, the first time in a half-century of powering endless numbers of rear-driveGM cars, the company's famous ''small-block'' V-8 will turn up in a front-drivemodel for the first time ever.
General Motors'new Gen IV 5300 5.3L V-8 (LS4) engine will power the 2006 Pontiac Grand PrixGXP next fall, and Dave Muscaro, the assistant chief engineer of small-blockV-8s for passenger cars, says it was ''engineered specifically for front-drivelayouts,'' of which GM has many.
Because itsprimary responsibility is performance, the LS4 has been tweaked to deliver 290hp and 325 lb-ft of torque, though those are both called ''estimates'' thissoon in the development process. Don't be surprised if the production model'snumbers go even higher.
Mostimpressively of all, the LS4 V-8 delivers 90 percent of that torque between1,500 and 5,200 rpm, which ought to deliver very satisfying acceleration in theGrand Prix sedan at any speed and in any situation.
Not so long ago,this kind of grunt would have been impossible because of the likelihood of thedreaded ''torque steer,'' which is auto-speak for a vehicle having so muchpower that it affects the steering system and makes the steering wheel twist. Thatapparently is not an issue in the Grand Prix GXP.
To get those V-6fuel economy levels, the 5.3-litre V-8 uses Displacement on Demand (DOD) technology,which helps the vehicle realize fuel economy gains of up to 12 percent on the Americanfuel economy test procedures.
In the realworld, this engine or any other with DOD delivers fuel economy gains invirtually every situation except those acceleration moments. It's particularlygood at using less fuel in constant speed situations, when it can turn off halfof those fuel-using cylinders.
Muscarounderscores the point that ''the engine returns to V-8 mode the instant thecontroller determines the vehicle speed or load requires additional power. Theprocess is seamless and virtually imperceptible.'' That is certainly the way itworks in GM vehicles already using DOD, and there's no reason to imagine itwon't also apply here.
''There'snothing like the satisfying feel of a V-8 engine,'' says Muscaro, ''and the5300 provides a level of performance rarely available in competitors' vehicles.But when all eight cylinders aren't required to maintain performance, DODtechnology effectively turns the engine into a more efficient V-4.''
Muscaro pointsout that the all-aluminum 5300 V-8 is the third displacement offering of theGen IV small-block, which was introduced in the 2005 Chevrolet SSR, GTO andCorvette, as well as several 2005 GM SUVs.
''The 5300 V-8shares a common architecture with these other versions,'' Muscaro says, ''includinga deep-skirt block, six-bolt cross-bolted main bearing caps, and structural oilpan, but is modified to accommodate the 'east-west' mounting position of theGrand Prix's front-wheel-drive chassis.''
To fit the''sideways'' positioning in the Grand Prix, several changes were made toshorten the engine's overall length. The crankshaft was shortened by 13 mm -- 3mm at the rear and 10 mm at the front -- and the entire accessory drive systemwas designed to reduce space. The accessories, including the water pump and thepower steering pump, are driven on a single-belt drive system, which Muscarosays is the longest drive system in a GM vehicle.