Atlas is a name for a family of modern inline piston engines for trucks from General Motors. The series debuted in 2003 with the Chevrolet TrailBlazer, and is also used in the Chevrolet Colorado and their GMC twins, the Envoy and Canyon. In production, the engines use GM's Vortec name, and I4, I5, and I6 engines are all part of the same family, sharing the same manufacturing equipment, rods, pistons, valves, and other parts. They feature 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 Atlas program began in 1995 along with the planning for GM's next-generation midsize SUVs and pickup trucks. These vehicles were designed around the I6 engine. The I6 version was used in a Baja 2000 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 hillclimb.

LL8

The LL8 (or Vortec 4200), is a straight-6 truck engine. It was the first Atlas engine, and was designed for GM's new SUV line. Power is 275 hp (205 kW) and torque is 275 ft.lbf (373 Nm). The Atlas LL8 was on the Ward's 10 Best Engines list for 2002 through 2005.

LL8 Applications:

• 2002-2004 GMC Envoy, Envoy XL, and Envoy XUV
• 2002-2004 Chevrolet TrailBlazer and TrailBlazer EXT
• Buick Ranier
• Isuzu Ascender
• Saab 9-7X

L52

The L52 (also called Vortec 3500), is a straight-5 truck engine. It displaces 3.5 L (3460 cc) and shares much with the rest of the Atlas family. It produces 220 hp (164 kW) and 225 ft.lbf (305 Nm).

It is used in the following vehicles:

• 2004 Chevrolet Colorado
• 2004 GMC Canyon
• 2006 Isuzu i-350
• 2006 Hummer H3

LK5

The straight-4 LK5 engine is sold as the Vortec 2800 in GM trucks. Like its Atlas brothers, the LK5 has dual overhead cams, and shares their 93 mm bore and 102 mm stroke. The LK5 displaces 2.8 L (2770 cc) and produces 175 hp (131 kW) and 185 ft.lbf (251 Nm).

It is used in the following vehicles:

• 2004 Chevrolet Colorado
• 2004 GMC Canyon
• 2006 Isuzu i-280