General Motors Atlas engine
Atlas is a name for a family of modern inline piston engines for trucks from General Motors, used in the GMT 355 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, 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. The Vortec 2800, 2900, 3500, 3700 and 4200 engines have  replaceable steel cylinder liners in the block. 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 I6 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. LL8 (Vortec 4200). The LL8 (or Vortec 4200), is a straight-6 gasoline engine produced between 2002 and 2009. It was the first Atlas engine, and was introduced in 2002 for the Chevrolet TrailBlazer, GMC Envoy, and Oldsmobile Bravada, the engine is also in use in the Buick Rainier, Saab 9-7X, and the Isuzu Ascender. It displaces , with a 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 at 6000 rpm and torque was at 3600 rpm. 2003 saw a slight bump in power to , while torque was unchanged. For 2006, power was increased to at 6000 rpm and torque to ) 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. Engine redline is 6300 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 closing  of the Moraine, Ohio plant and the termination of the GMT360 platform (Chevrolet TrailBlazer, GMC Envoy, etc.) the production of the LL8 was also terminated. Applications: L52 (Vortec 3500). The L52 (also called Vortec 3500), is a straight-5 DOHC engine produced between 2004 and 2006. It displaces , with a bore and stroke. Dynoed at the flywheel it produces at 5600 rpm and at 2800 rpm. Engine redline is 6300 rpm. Applications: LLR (Vortec 3700). The LLR (also called Vortec 3700), is a straight-5 DOHC engine with dual balance shafts produced between 2007 and 2012. It displaces , courtesy of a larger  bore while keeping the stroke. The LLR also corrected the head issue found in the "L52". It produces at 5600 rpm and at 4600 rpm. Engine redline is 6300 rpm. This five-cylinder motor achieves better fuel economy and performance than the six cylinder, but with more power and torque than the four cylinder. Applications: LK5 (Vortec 2800). The LK5 (also called the Vortec 2800) is a straight-4 DOHC engine produced between 2004 and 2006, with a bore and stroke. It produces at 5600 rpm and of torque at 2800 rpm. The engine redline is 6300 rpm. Applications: LLV (Vortec  2900). The LLV (also called Vortec 2900) is a straight-4 DOHC engine produced between 2007 and 2012, with a bore and a stroke. It replaced the LK5 and produced at 5600 rpm and of torque at 2800 rpm. Engine redline is 6300 rpm. Applications: