VORTEC 4200 4.2L I-6 (LL8)
2006 model year summary
• Increased horsepower and torque outputs
• Higher 10.3:1 compression ratio
• Improved air flow
• Mass air flow sensor
• Improved A.I.R. system
• Improved ignition coils
• Piston rod squirters
Full descriptions of new or changed features
Increased horsepower and torque
The Vortec 4200, already noted for providing peak power and torque emulating that of
competitors’ larger-displacement V-8s, delivers 16 more horsepower for 2006. Its new
rating is 291 hp and 277 lb.-ft. of torque. The power increase resulted from a higher
compression ratio and improved engine breathing. GM Powertrain’s participation in the
new SAE test certification procedure provides more accurate readings of in-vehicle
performance by using more exact measures of exhaust backpressure and also
accounting for loads put on the engine by the accessory drive.
Increased compression ratio
The Vortec 4200’s compression ratio increased to 10.3:1 as a result of changes to its
piston profile, which lowered the volume in the combustion chamber. Even with its higher
compression ratio, the engine continues to maximize fuel economy by allowing
customers to use regular or unleaded fuel.
Improved air flow
Improved performance also results from increased airflow into and through the engine. A
larger (38.7 mm) intake valve and larger (33.5 mm) exhaust valve allow more air to flow through, and the camshaft also provides more lift to allow the valves to stay open longer.
Mass air flow sensor
A mass air flow system helps reduce emissions, allowing the Vortec 4200 to meet
California LEV II emissions requirements while also improving its fuel economy.
The mass air flow (MAF) sensor (replacing a previous speed density fuel control system)
more accurately measures air flow into the engine, eliminating variability in a number of
conditions including changes in altitude and temperature, and allows more precise fuel
and spark response.
The MAF is lightweight and has a modular design, using an integrated intake air
temperature sensor. The electronics, located in the center of the sensor’s flow tube, are
air cooled by the intake air. The output calibration is precisely programmed into the
module.
A.I.R. system
The Air Injection Reaction (A.I.R) System, which pumps air into the port of each cylinder
head, has also been upgraded to assist in reducing emissions. During the casting
process, the A.I.R. port is now cast right into the cylinder head for improved air flow.
Ignition coils
The ignition system uses more compact coils, which also provide better reliability/
durability and make better use of its energy. Their more compact size saves an entire
coil’s worth of weight. Enhanced durability has been proven from the coils’ use in other
Gen III engines.
Piston rod oil squirters
The piston, inside the cylinder bore of the engine block, transfers energy through the
connecting rod to the crankshaft. For improved durability and quietness the piston rod is
now drilled with a tiny (less than 1/8th mm) hole, which allows oil to be sprayed on the
cylinder wall, providing a cushioning layer on the sides of the piston which rides on the
film of oil.
The oil is originally pumped into the crankshaft, whose journals have cross-drilled holes.
As the crankshaft rotates, pumping oil through the journals, the oil is fed from the
journals through the piston rod bearing into the piston rod itself. Its open orifice then
allows the oil to be sprayed into the cylinder wall.
Overview
The award-winning Vortec 4200 4.2L I6 (LL8), which won rave reviews in virtually every
automotive media outlet when introduced in 2002 and awards, including three
consecutive appearances on Ward's Auto World's 10 Best Engines list, has continually
been refined to optimize value and performance.
During the five years since the engine’s launch, virtually every system and technology,
from emissions control to engine management to sealing, has been examined and
refined. In 2003, the Vortec 4200 was fitted with polymer-coated pistons that reduce
engine noise and enhance durability. The oil pump was refined to limit noise; and the
cam-chain tensioner was improved for quieter operation. For model year 2004, the
Vortec 4200 was introduced in the all-new Buick Rainier and Isuzu Ascender. In ’05 its
variable valve timing, or cam phasing, system was equipped with a new state-of-the-art
vane phaser. Along with previous GM midsize SUVs, ’05 also saw the Vortec 4200
introduced in the Saab’s first 9-7X SUV.
The Vortec 4200 originally debuted as the first inline six-cylinder engine in GM
Powertrain’s lineup in nearly 20 years. While the industry largely had turned away from
the inline six, GM recognized that, given careful design and development, the inherent
advantages of inline six-cylinder architecture were perfect for the new millennium. With
the technical sophistication of premium passenger car engines and the power of
competitors’ V-8s, the Vortec 4200 is no ordinary inline six. Its flexible architecture
provides the foundation for a range of inline engines, maximizing the return on corporate
investment while exceeding customers’ performance expectations.
An exceptionally light, rigid engine block and cylinder head combination, cast with the
GM's patented lost foam process, provide the foundation for the Vortec 4200’s success.
All-aluminum construction means less weight than conventional cast-iron truck engines,
and less weight means improved fuel economy. The bottom end of the engine derives strength through many features, starting with a bearing beam, or ladder, that connects
the seven main bearing caps to further stiffen the engine’s structure. The oil pan bolts to
the transmission bell housing as well as the engine block, eliminating points of vibration
and making the complete engine more like a single casting. The oil pan also gives “panaxle”
all-wheel drive capability to trucks equipped with the Vortec 4200. A passage cast
through the width of the oil pan allows a drive axle to pass through it rather than under it,
allowing the engine to be placed lower in the vehicle for a more compact package that
improves the vehicle’s handling dynamics and gives designers greater styling flexibility.
The Vortec 4200's feature list reads like those for premium luxury/performance car
engines: dual-overhead cam cylinder head, four valves per cylinder, roller-follower valve
actuation and exhaust-cam phasing; a 10.3:1 compression ratio that delivers the
seemingly incompatible benefits of high compression and regular-grade fuel; Electronic
Throttle Control (ETC); and direct accessory mounting.
Vehicle platform teams recognize the Vortec 4200’s strengths, yet its design advantages
and premium features mean little if the finished product doesn’t deliver what customers
demand, like low maintenance. With Vortec 4200, oil changes are the only scheduled
maintenance during the first 100,000 miles of operation, and even those are as stressfree
as possible. GM’s Oil Life System (GMOLS) advises an oil change when it’s actually
needed, based on real-world vehicle operation, rather than a predetermined mileage
interval. The oil filter is easily accessible from underneath Vortec 4200-equipped
vehicles and is mounted pointing straight down, reducing the potential for spilling oil
during removal.
Most of all, customers demand performance and economy. Along with delivering even
more peak horsepower and torque comparable to competitors’ larger-displacement V-8s,
the Vortec 4200 also has higher EPA mileage ratings (based on published figures
available in March 2005).
The Vortec 4200 is produced in Flint, Michigan.
