| General Motors Atlas | |
|---|---|
 | |
| Overview | |
| Manufacturer | General Motors Corporation |
| Also called | Vortec |
| Production | 2002–2012 |
| Layout | |
| Configuration | Straight-4, Straight-5, and Straight-6 |
| Displacement |
|
| Cylinder bore |
|
| Piston stroke | 102 mm (4.02 in) |
| Cylinder block material | Aluminum |
| Cylinder head material | Aluminum |
| Valvetrain | DOHC 4 valves x cyl. with VVT |
| Compression ratio | 10.0:1 |
| RPM range | |
| Max. engine speed | 6,300 RPM |
| Combustion | |
| Fuel system | Multi-point fuel injection |
| Fuel type | Gasoline |
| Oil system | Wet sump |
| Cooling system | Water-cooled |
| Output | |
| Power output | 175–291 hp (130–217 kW) |
| Torque output | 185–277 lb⋅ft (251–376 N⋅m) |
| Chronology | |
| Predecessor | |
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,[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.
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.
- ^ a b "5 Cylinder Engine - Vortec 3500". Retrieved 2011-10-13.
- ^ "Improved Performance and Efficiency Highlight a Robust Powertrain Lineup for '05". Archived from the original on 2010-01-08.
- ^ Cite error: The named reference
2006_LK5was invoked but never defined (see the help page). - ^ Cite error: The named reference
2006_L52was invoked but never defined (see the help page). - ^ 6 Cylinder Engine - Straight Six - Explained, retrieved 2023-06-17