PONTIAC – General Motors’ new Gen IV 5300 5.3L V-8 (LS4) engine debuts in the 2006 Pontiac Grand Prix GXP, making it the first V-8 offered in a Grand Prix since 1987. It also marks the first time since the small-block was introduced 50 years ago that it has been offered in a front-wheel-drive car.
Engineered specifically for front-drive layouts, the 5300 V-8 is estimated to produce 290 horsepower and 325 lb.-ft. of torque. It incorporates Displacement on Demand technology (DOD), which helps the vehicle realize fuel economy gains of up to 12 percent per the EPA federal fuel economy test procedures. It does this by seamlessly alternating between eight- and four-cylinder operation.
When matched with the inherent smoothness and torque of the V-8 configuration, the 5300 V-8 delivers strong performance – 90 percent of torque is available between 1500 rpm and 5200 rpm – and surprising economy. It’s a combination most competitors’ V-6 offerings can’t match.
“Over 50 years, the small-block V-8 has proven itself more adaptable than anyone could have imagined,” said Dave Muscaro, assistant chief engineer of small-block V-8 for passenger cars. “The small-block family has a tradition dating back to 1955 in which an excellent design makes possible the additions of new technology. The Displacement on Demand-capable 5300 V-8 is a fine example of that tradition.”
Family ties
The all-aluminum 5300 V-8 is the third displacement offering of the Gen IV small-block, which was introduced in the 2005 Chevrolet SSR, GTO and Corvette, as well as several 2005 GM SUVs. The 5300 V-8 shares a common architecture with these other versions, including a deep-skirt block, six-bolt cross-bolted main bearing caps, and structural oil pan, but is modified to accommodate the “east-west” mounting position of the Grand Prix’s front-wheel-drive chassis.
To fit the “sideways” positioning in the Grand Prix, several changes were made to shorten the engine’s overall length. The crankshaft was shortened by 13 mm – 3 mm at the rear and 10 mm at the front – and the entire accessory drive system was designed to reduce space. The water pump and all other accessories, including the power steering pump, are driven on a single-belt drive system – the longest drive system in a GM vehicle.
Engineers devised an elongated water pump manifold, which features a remote-mounted pump that feeds the stock Gen IV coolant passages via the unique manifold. The design allowed the drive system to be mounted closer to the engine block. Because of the 5300 V-8’s relatively low inertia, which can be up to 50 percent less at the crankshaft damper than a 6.0L V-8, a hydraulic belt tensioner was used instead of a conventional rotary tensioner.
Unique position
The sideways position of the 5300 V-8 required revisions to the lubrication system. Engineers tested 5300 V-8 equipped test vehicles on racetracks, subjecting them to high-load turns that guided the development of special oil pan baffles that ensure lubrication during cornering. In addition, because Gen IV engines don’t have a block-mounted oil filter – it’s located on the oil pan – the 5300 V-8’s filter offers easy access.
The GM Oil Life System oil-change indicator system is standard, which can reduce the frequency of oil changes during the engine’s operating life. With the system, the engine control module (ECM) records cumulative data on a number of variables, including engine rpm, temperature, load or rpm variance and length of operation at any given load and temperature. Using this information, the system calculates oil degradation and recommends an oil change when the oil is near the end of its useful life – in other words, when an oil change is actually needed.
Other 5300 V-8 features include:
Lightweight, three-piece friction-welded composite intake manifold
Aluminum high-flow cylinder heads similar to 6.0L V-8 (LS2)
Aluminum engine block with cross-bolted main bearing caps
Full-floating pistons
Electronic throttle control integrated with a new engine controller
10.0:1 compression ratio for fuel-efficient performance
Unique camshaft designed for DOD technology
GM Oil Life System to minimize required oil changes
Because of the front-drive layout, the 5300 V-8’s exhaust manifold routing includes two manifolds joined by a single crossover pipe, which connect to a single underbody catalytic converter. The crossover pipe allows the use of a single oxygen sensor, unlike north/south V-8 applications that have two oxygen sensors.
Displacement on Demand technology
GM’s Displacement on Demand technology debuted in 2005 GM extended midsize SUVs equipped with the Vortec 5.3L V-8 (LH6) engine. With the 5300 V-8 (LS4), DOD technology enables fuel economy gains of up to 12 percent in certain driving conditions by reducing the number of cylinders engaged in the combustion process. A sophisticated, next-generation engine controller determines when to deactivate cylinders, allowing the engine to maintain vehicle speed in lighter-load conditions such as highway cruising. When the cylinders are deactivated, the engine effectively operates as a V-4, with alternate cylinders on each cylinder bank disabled. The engine returns to V-8 mode the instant the controller determines the vehicle speed or load requires additional power. The process is seamless and virtually imperceptible.
“There’s nothing like the satisfying feel of a V-8 engine and the 5300 V-8 provides a level of performance rarely available in competitors’ vehicles,” said Muscaro. “But when all eight cylinders aren’t required to maintain performance, DOD technology effectively turns the engine into a more efficient V-4.”
