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,[3][4] balance shafts being unnecessary in the 6-cylinder.[5]
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.
It displaces 4.2L (4,160cc; 253.9cuin), with a 93mm ×102mm (3.66in ×4.02in) 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 270hp (201kW) at 6,000 rpm and torque was 275lb⋅ft (373N⋅m) at 3,600 rpm. 2003 saw a slight bump in power to 275hp (205kW), while torque was unchanged. For 2006, power was increased to 291hp (217kW) at 6,000 rpm and torque to 277lb⋅ft (376N⋅m)) 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.[6]
The LLR (also called Vortec 3700), is a straight-5DOHC engine produced from 2007 through 2012. It displaces 3.7L; 222.9cuin (3,653cc), courtesy of a larger 95.5mm (3.76in) bore while keeping the 102mm (4.02in) stroke. The LLR also corrected the head issue found in the L52. It produces 242hp (180kW) at 5,600 rpm and 242lb⋅ft (328N⋅m) at 4,600 rpm. The engine redline is 6,300 rpm.[6] This five-cylinder engine achieves better fuel economy than the six-cylinder with more power and torque than the four-cylinder.[1]
The L52 (also called Vortec 3500), is a straight-5DOHC engine produced from 2004 through 2006. It displaces 3.5L; 211.1cuin (3,460cc), with a 93mm ×102mm (3.66in ×4.02in) bore and stroke. Dynoed at the flywheel it produces 220hp (164kW) at 5,600 rpm and 225lb⋅ft (305N⋅m) at 2,800 rpm. The engine redline is 6,300 rpm.[4]
The LLV (also called Vortec 2900) is a 2.9L; 178.3cuin (2,921cc)straight-4DOHC engine produced between 2007 and 2012, with a 95.5mm ×102mm (3.76in ×4.02in) bore and a stroke. It replaced the LK5 and produced 185hp (138kW) at 5,600 rpm and 190lb⋅ft (258N⋅m) of torque at 2,800 rpm. The engine redline is 6,300 rpm.[7]
The LK5 (also called the Vortec 2800) is a 2.8L; 169.0cuin (2,770cc)straight-4DOHC engine produced between 2004 and 2006, with a 93mm ×102mm (3.66in ×4.02in) bore and stroke. It produces 175hp (130kW) at 5,600 rpm and 185lb⋅ft (251N⋅m) of torque at 2,800 rpm. The engine redline is 6,300 rpm.[3]
This article uses material from the Wikipedia article GM_Atlas_engine, and is written by contributors.
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