Editing General Motors Atlas engine (section)

{{Infobox automobile engine
| image = GM Atlas I6 front.jpg
| name = General Motors Atlas
| aka = Vortec
| manufacturer = [[General Motors Corporation]]
| configuration = [[Straight-4]], [[Straight-5]], and [[Straight-6]]
| production = 2002–2012
| predecessor = {{ubl | [[Chevrolet Turbo-Thrift engine]]|[[General Motors 122 engine]]}}
| redline = 6,300&nbsp;rpm
| displacement = {{ubl | {{cvt|2770|cc|L cuin|1|order=flip}}|{{cvt|2921|cc|L cuin|1|order=flip}}|{{cvt|3460|cc|L cuin|1|order=flip}}|{{cvt|3653|cc|L cuin|1|order=flip}}|{{cvt|4160|cc|L cuin|1|order=flip}}|}}
| compression  = 10.0:1
| block = [[Aluminum]]
| head = Aluminum
| valvetrain = [[DOHC]] [[Multi-valve#Four valves|4 valves x cyl.]] with [[Variable valve timing|VVT]]
| fuelsystem = [[Multi-point fuel injection]]
| fueltype = [[Gasoline]]
| oilsystem = [[Wet sump]]
| coolingsystem = [[Radiator (engine cooling)|Water-cooled]]
| bore = {{ubl | {{cvt|93|mm|in|2}}| {{cvt|95.5|mm|in|2}}}}
| stroke = {{cvt|102|mm|in|2}}
| power = {{cvt|175-291|hp|kW|0}}
| torque = {{cvt|185-277|lbft|Nm|0}}
}}
'''Atlas''' is a name for a family of modern [[straight engine|inline]] [[piston engine]]s for [[truck]]s 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 [[Chevrolet Colorado|Colorado]], the [[GMC Envoy]] and [[GMC Canyon|Canyon]], the [[Hummer H3]], [[Isuzu Ascender]] and [[Isuzu i-370|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,<ref name="counterman">{{cite web|url=https://www.counterman.com/tech-feature-straight-look-vortec-3500-straight-five-engine/|title=5 Cylinder Engine - Vortec 3500|accessdate=2011-10-13}}</ref> [[variable valve timing]] on the [[exhaust manifold|exhaust]] side, [[electronic throttle control]], and a special oil pan with a pass-through for the [[half shaft]]s 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 [[Exhaust gas recirculation|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.<ref name="2005_GM">{{cite web|title=Improved Performance and Efficiency Highlight a Robust Powertrain Lineup for ’05|archive-url=https://web.archive.org/web/20100108030402/http://archives.media.gm.com/division/2005_prodinfo/powertrain/index.html|archive-date=2010-01-08|url=http://archives.media.gm.com/division/2005_prodinfo/powertrain/index.html}}</ref>

The Atlas engines feature aluminum cylinder blocks and heads, with the cylinder bores featuring replaceable steel [[cylinder liner]]s.<ref name="counterman"/> The 4- and 5-cylinder versions feature dual balance shafts,<ref name="2006_LK5" /><ref name="2006_L52" /> balance shafts being unnecessary in the 6-cylinder.<ref>{{Citation |title=6 Cylinder Engine - Straight Six - Explained |url=https://www.youtube.com/watch?v=w5NZsc1oQpU |access-date=2023-06-17 |language=en}}</ref>

The Atlas program began in 1995 along with the planning for GM's next-generation mid-size [[Sport utility vehicle|SUVs]] and [[pickup truck]]s. 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 engine]]s. 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|Tonawanda Engine plant]] in [[Tonawanda (town), New York|Tonawanda, New York]], near [[Buffalo, New York|Buffalo]].