| General Motors Atlas | |
| Aka: | Vortec |
| Manufacturer: | General Motors Corporation |
| Configuration: | Straight-4, Straight-5, and Straight-6 |
| Production: | 2002–2012 |
| Redline: | 6,300 RPM |
| Compression: | 10.0:1 |
| Block: | Aluminum |
| Head: | Aluminum |
| Valvetrain: | DOHC 4 valves x cyl. with VVT |
| Fuelsystem: | Multi-point fuel injection |
| Fueltype: | Gasoline |
| Oilsystem: | Wet sump |
| Coolingsystem: | Water-cooled |
| Stroke: | 1022NaN2 |
| Power: | NaN0NaN0 |
| Torque: | NaN0NaN0 |
Atlas is a name for a family of modern inline piston engines for trucks from General Motors, used in the GMT355 and GMT360 platforms. The series debuted in 2002 with the Oldsmobile Bravada, and is also used in the Buick Rainier, the Chevrolet TrailBlazer and Colorado, the GMC Envoy and Canyon, the Hummer H3, Isuzu Ascender and i-370, and the Saab 9-7X. The engines use GM's Vortec name, and Straight-4, Straight-5, and Straight-6 engines are all part of the same family, sharing the same manufacturing equipment, rods, pistons, valves, and other parts. They feature coil-on-plug ignition systems,[1] variable valve timing on the exhaust side, electronic throttle control, and a special oil pan with a pass-through for the half shafts in four-wheel drive vehicles. The inclusion of VVT on the exhaust camshaft side allows the Atlas series to meet emissions standards without the use of EGR, simplifying the engine design and increasing power for a broad power curve. The LL8 shares 75% of its components with the LK5 and L52; while the LK5 and L52 share 89% of their components.[2]
The Atlas engines feature aluminum cylinder blocks and heads, with the cylinder bores featuring replaceable steel cylinder liners.[1] The 4- and 5-cylinder versions feature dual balance shafts, balance shafts being unnecessary in the 6-cylinder.
The Atlas program began in 1995 along with the planning for GM's next-generation mid-size SUVs and pickup trucks. These vehicles were designed around the I6 engine. The I6 version was used in a Baja 1000 racing truck, winning its first race in a class that also included V8 engines. Another I6-powered truck won the truck class at the Pikes Peak International Hillclimb.
The Atlas engines were produced at the Flint Engine South plant in Flint, Michigan, while the I4 and I5 versions were produced at the Tonawanda Engine plant in Tonawanda, New York, near Buffalo.
The LL8 (or Vortec 4200), is a straight-6 gasoline engine produced from 2002 to 2009. It was the first Atlas engine, and was introduced in 2002 for the Chevrolet TrailBlazer, GMC Envoy, and Oldsmobile Bravada. The engine was also used in the Buick Rainier, Saab 9-7X, and Isuzu Ascender.
It displaces, with a NaN2NaN2 bore and stroke. It has four valves per cylinder, utilizes dual-overhead cams (DOHC) design, and features variable valve timing on the exhaust cam, a first for GM inline engines. When introduced, this engine's power was 2700NaN0 at 6,000 rpm and torque was 2750NaN0 at 3,600 rpm. 2003 saw a slight bump in power to 275hp, while torque was unchanged. For 2006, power was increased to 2910NaN0 at 6,000 rpm and torque to 2770NaN0) at 4800 rpm with the addition of a MAF and a complete internal redesign of the engine; however, due to the new SAE rating procedures, ratings can vary slightly between years. The engine redline is 6,300 rpm. The LL8 was on the Ward's 10 Best Engines list for 2002 through 2005 and was the basis for all the other Atlas engines. With the closure of the Moraine, Ohio, plant and the discontinuation of the GMT360 platform (Chevrolet TrailBlazer, GMC Envoy, etc.), production of the LL8 also ended.
Applications:
The LLR (also called Vortec 3700), is a straight-5 DOHC engine produced from 2007 through 2012. It displaces 3653cc, courtesy of a larger 95.5mm bore while keeping the 1022NaN2 stroke. The LLR also corrected the head issue found in the L52. It produces 2420NaN0 at 5,600 rpm and 2420NaN0 at 4,600 rpm. The engine redline is 6,300 rpm. This five-cylinder engine achieves better fuel economy than the six-cylinder with more power and torque than the four-cylinder.[1]
Applications:
The L52 (also called Vortec 3500), is a straight-5 DOHC engine produced from 2004 through 2006. It displaces 3460cc, with a NaN2NaN2 bore and stroke. Dynoed at the flywheel it produces 2200NaN0 at 5,600 rpm and 2250NaN0 at 2,800 rpm. The engine redline is 6,300 rpm.[3]
Applications:
The LLV (also called Vortec 2900) is a 2921cc straight-4 DOHC engine produced between 2007 and 2012, with a NaN2NaN2 bore and a stroke. It replaced the LK5 and produced 1850NaN0 at 5,600 rpm and 1900NaN0 of torque at 2,800 rpm. The engine redline is 6,300 rpm.
Applications:
The LK5 (also called the Vortec 2800) is a 2770cc straight-4 DOHC engine produced between 2004 and 2006, with a NaN2NaN2 bore and stroke. It produces 1750NaN0 at 5,600 rpm and 1850NaN0 of torque at 2,800 rpm. The engine redline is 6,300 rpm.[4]
Applications: