LOS ANGELES – The Impala and Monte Carlo’s new powertrain lineups are led by a family of sophisticated V-6 engines that incorporates features such as cam phasing to deliver excellent power, economy and value. And, for the first time in a front-wheel-drive layout, the legendary small-block V-8 returns to the Impala and Monte Carlo.
A new 3500 V-6 is standard in the Impala and Monte Carlo. With 210 horsepower (156 kw) and 220 lb.-ft. (304 Nm) of torque, it offers more standard power than previous models and, in fact, delivers more power as a base engine than some key competitors’ top (or only) offering. Up-level models offer the 3900 V-6 built on the same architecture and incorporating a variable-length intake manifold. It is rated at 240 (179 kw) horsepower and 245 lb.-ft. (339 Nm) of torque.
Impala SS and Monte Carlo SS models are equipped with the new LS4 5.3L small-block V-8 with Displacement On Demand (DOD) technology. Developed exclusively for front-drive applications, the 5.3L produces 303 horsepower (226 kw) and 323 lb.-ft. (438 Nm) of torque with DOD helping to reduce fuel consumption by up to 12 percent in certain light-load driving conditions.
3.5L & 3.9L V-6
These new-generation V-6s represent the first overhead-valve engine family to incorporate variable valve timing, which optimizes performance and economy and promotes lower emissions at every rpm level. Vehicles in the United States equipped with the 3.5L engine are compatible with E85 ethanol fuel, allowing the vehicle to run on any combination of gasoline and/or E85. In Canada, the E85-compatible 3500 engine is optional.
The 3.5L V-6, rated at 210 horsepower and 220 lb.-ft. of torque, delivers more than 11 percent more power and 10 percent more torque when compared with the 2005 Impala’s 180 horsepower and 200 lb.-ft. The 3.9L V-6 offers more power and usable torque, with 90 percent of its 245 lb.-ft. available from 1800 to 5800 rpm.
“This brand-new family of engines that is designed to meet contemporary – and future – expectations for performance, economy, smoothness and durability,” said Gary Horvat, assistant chief engineer for V-6 engines. “State-of-the-art technology results in output and economy – attributes that continue to make the cam-in-block design a high-value design.”
The V-6 engines have an all-new cylinder block casting and new cylinder heads, sharing only valve lifters with any previous GM engine. The 3.5L V-6 and 3.9L V-6 share more than 80 percent common parts, with the 3.9L V-6 achieving increased displacement with a longer-stroke crankshaft.
The new V-6s use a 60-degree “V” configuration, which is naturally balanced, ensuring drivetrain smoothness and eliminating the need for costly balance shafts. Unique to this engine family, however, are offset cylinder bores – the intersection of the cylinder bores’ centerline is not at the crankshaft centerline. In this case, the bores’ centerline is 3 mm lower than the crankshaft. This was done to allow packaging room for the wider bores, as well as the longer stroke of larger-displacement versions, such as the 3.9L V-6.
Additional technical details of the new V-6 engine family include:
Perhaps the most significant technological feature of the new V-6 engines is the adaptation of variable valve timing – a first for cam-in-block engines. The system incorporates a vane-type camshaft phaser that changes the angular orientation of the camshaft, thereby adjusting the timing of the intake and exhaust valves to optimize performance and economy, and help lower emissions. It offers infinitely variable valve timing in relation to the crankshaft.
The cam phasing creates “dual equal” valve timing adjustments. In other words, the intake valves and exhaust valves are varied at the same time and at the same rate. The cam phaser vane is attached to the camshaft on the front journal – a technique made easier by the award-winning “assembled-camshaft” design pioneered by GM. With this design, separate camshaft lobes are installed on a hollow camshaft tube rather than the traditional method of grinding a camshaft from a single piece of stock.
Hydraulic roller lifters with low-friction followers complement the unique camshaft and a new, more powerful E67 ECM, with its 32-bit processor, enables the engine’s cam phasing. Variable valve timing also necessitated a more precise cam position sensor, so engineers developed a new target ring. The ring has four equally spaced segments that communicate the camshaft’s position quicker and more accurately than previous systems that used just a single segment.
And while there are many architectural and component similarities, the V-6 engines are different in important areas of tuning optimization. The camshafts, for example, are unique between them, as they are matched to each engine’s respective bore-and-stroke characteristics.
A new “U”-shaped coolant flow system also is used in this new engine family. With it, coolant follows a specific path: it enters the engine at the front of the block and is carried to the back, before flowing into the rear of the cylinder head. As the coolant enters the rear of the cylinder head it flows forward, completing a U-shaped path that delivers uniform cooling.
Engineers also placed the thermostat on the inlet side of the system, which allows the engine – and the vehicle’s interior – to warm up quickly in cold weather. Also, the coolant system has an on-engine fill point. It is located at the high-point in the system (near the power steering pump), easing the task of adding coolant because air cannot be trapped. Therefore, no “burping” of the system through bleed screws is required.
Premium refinements
The new V-6 family incorporates a host of features typically reserved for high-cost premium engines:
Oil piston coolers – Every cylinder has piston oil squirters that ensure optimal lubrication and cooling.
Multilayer steel (MLS) head gaskets – These premium gaskets offer great durability over conventional graphite gaskets.
58X Quick Sync ignition – The 3.5 V-6’s Direct Ignition System uses 58 sensors to more accurately determine the position of the crankshaft, ensuring extremely accurate ignition performance.
Electronic throttle control (ETC) – Throttle operation is handled by more accurate electronic signals, eliminating the need for conventional throttle cables. Cruise control functions are incorporated with ETC, reducing underhood complexity. The engine draws air through a 72-mm single-bore throttle body.
Next-gen Multec 3.5 fuel injectors – Part of the engine’s returnless fuel system, this next-generation fuel injectors have improved hot fuel handling characteristics and improved plug resistance. Injectors in E85-capable engines have a diamond-like coating on the injector valve.
These new V-6s also incorporate long-life components such as 100,000-mile iridium-tip spark plugs and coolant, as well as premium gaskets and sealers that help ensure maintenance-free operation. The GM Oil Life System (GMOLS) also is standard.
GMOLS can extend the intervals between oil changes and reduce the amount of oil an owner buys over the operating life of the vehicle. With GMOLS, the need for an oil change is determined by an algorithm that measures engine starts, temperature and other factors. An indicator on the instrument panel illuminates when it’s time for an oil change.
LS4 5.3L V-8
The small-block V-8 returns to the Impala SS and Monte Carlo SS for 2006, but with a historic twist – transverse front-wheel-drive.
Engineered specifically for front-drive layouts, the 5.3L V-8 produces 303 horsepower and 323 lb.-ft. of torque – with 90 percent of torque available from 1500 rpm to 5500 rpm. It also incorporates Displacement On Demand technology, which debuted in 2005 GM extended midsize SUVs equipped with the Vortec 5.3-liter LH6 V-8 engine.
With the 5.3L engine, 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 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.
“The 5.3-liter engine returns the satisfying feel of the small-block V-8 engine to the Impala and Monte Carlo – vehicles that were originally launched with the small-block,” said David Muscaro, assistant chief engineer of small-block V-8 for passenger cars. “But when all eight cylinders aren’t required to maintain performance, DOD technology effectively turns the engine into a more efficient V-4.”
The all-aluminum 5.3L is based on the Gen IV small-block architecture – the same as the 6.0L V-8 found in the 2005 Corvette and SSR – but it is modified to accommodate the “east-west” mounting position of the Impala and Monte Carlo’s front-wheel-drive chassis. To fit this “sideways” position, several changes were made to shorten the engine’s overall length. The crankshaft was shortened by 13 mm 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.
Engineers devised a clever, 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 5.3L’s relatively low inertia, which can be up to 50 percent less at the crankshaft damper than an 6.0L V-8, a hydraulic belt tensioner was used instead of a conventional rotary tensioner.
Other 5.3L features include:
Displacement on Demand technology
GM’s Displacement On Demand technology debuted in 2005 GM extended midsize SUVs. With the 5.3L V-8, DOD technology enables fuel economy gains of up to 12 percent in certain light-load driving conditions by reducing the number of cylinders engaged in the combustion process.
The key to DOD’s efficiency and virtually imperceptible operation is a set of special two-stage hydraulic valve lifters, which allows the lifters of deactivated cylinders to operate without actuating the valves. These lifters, which are used only on the cylinders which are deactivated, have inner and outer bodies. They normally operate as a single unit, but when the engine controller determines cylinder deactivation conditions are optimal, it activates solenoids in the engine lifter valley that direct high-pressure oil to the switching lifters. The oil pressure activates a release pin inside the lifter which allows the outer body of the lifter to move independently of the inner body. With the pin released, the outer lifter body moves in conjunction with camshaft actuation, but the inner body does not move, holding the pushrod in place. This prevents the pushrod from actuating the valve, thereby halting the combustion process. Because the vibration and acoustic dynamics of the V-8 and V-4 modes are different, the exhaust system of DOD-equipped vehicles is tuned to compensate for the changes.
The 5.3L engine is mated to a high-performance Hydra-Matic 4T65-E electronically controlled four-speed automatic transmission. It is strengthened to handle the torque of the V-8 engine, while providing smooth, crisp shifting performance.
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