# General Motors Atlas engine
The **General Motors Atlas engine** family is a series of all-aluminum inline engines, built in four-, five-, and six-cylinder versions, that GM Powertrain developed in the late 1990s and produced from the 2002 model year through 2012, with its inline-four and inline-five applications outlasting the GMT360 SUV platform, which ended in 2009.[13](https://blog.consumerguide.com/forgotten-5-cylinder-engine/) Its flagship was the 4.2-liter Vortec 4200 inline six (RPO code LL8), the standard engine in the Chevrolet TrailBlazer, GMC Envoy, and their platform siblings, and a Ward's 10 Best Engines winner four years running.[1](https://saemobilus.sae.org/papers/gm-powertrains-new-vortec-4200-inline-6-engine-2001-01-0331) • [2](https://eu-assets.contentstack.com/v3/assets/blt7121b6ec5c11097b/blt568e1157ea176fc9/66224e6aeb73bb74c0aa253c/WardsAuto_OEM_Big_Story_March_2019.pdf)
| Key fact | Detail |
|---|---|
| Family | Inline four (Vortec 2800), inline five (Vortec 3500), and inline six (Vortec 4200 / LL8), all all-aluminum DOHC with four valves per cylinder[1](https://saemobilus.sae.org/papers/gm-powertrains-new-vortec-4200-inline-6-engine-2001-01-0331) • [3](https://www.theautochannel.com/news/2003/01/08/152551.html) |
| Vortec 4200 output | 270 hp SAE net at 6,000 rpm and 275 lb-ft (373 Nm) at 3,600 rpm; 4,160 cc from 93 mm bore × 102 mm stroke; 10:1 compression; 64 hp/L[2](https://eu-assets.contentstack.com/v3/assets/blt7121b6ec5c11097b/blt568e1157ea176fc9/66224e6aeb73bb74c0aa253c/WardsAuto_OEM_Big_Story_March_2019.pdf) |
| Torque character | 90% of peak torque available at just 1,600 rpm[2](https://eu-assets.contentstack.com/v3/assets/blt7121b6ec5c11097b/blt568e1157ea176fc9/66224e6aeb73bb74c0aa253c/WardsAuto_OEM_Big_Story_March_2019.pdf) |
| Emissions feature | Variable exhaust valve timing performs the EGR function internally, eliminating the EGR valve and cutting hydrocarbon emissions by 25%[2](https://eu-assets.contentstack.com/v3/assets/blt7121b6ec5c11097b/blt568e1157ea176fc9/66224e6aeb73bb74c0aa253c/WardsAuto_OEM_Big_Story_March_2019.pdf) |
| Awards | Ward's 10 Best Engines in 2002, 2003, 2004, and 2005[2](https://eu-assets.contentstack.com/v3/assets/blt7121b6ec5c11097b/blt568e1157ea176fc9/66224e6aeb73bb74c0aa253c/WardsAuto_OEM_Big_Story_March_2019.pdf) • [4](https://www.centuryu.com/uploads/1/4/4/6/144698822/2006_trailblazer.pdf) |
| Production | Flint Engine South Powertrain Plant, Flint, Michigan; I6 production ended in 2009, I4 and I5 in 2012[1](https://saemobilus.sae.org/papers/gm-powertrains-new-vortec-4200-inline-6-engine-2001-01-0331) • [5](https://chevromax.com/chevrolet-hub/guides/chevrolet-atlas-engine-family-explained-the-forgotten-inline-powerhouse/) |
## Design and development
The Vortec 4200 ended an absence of nearly two decades of inline sixes from GM vehicles, arriving for the 2002 model year as the standard engine in a new line of midsize SUVs. GM's previous inline six truck engine had been dropped in 1993, and the 4200 was GM's first new inline six truck engine in 15 years.[1](https://saemobilus.sae.org/papers/gm-powertrains-new-vortec-4200-inline-6-engine-2001-01-0331) • [2](https://eu-assets.contentstack.com/v3/assets/blt7121b6ec5c11097b/blt568e1157ea176fc9/66224e6aeb73bb74c0aa253c/WardsAuto_OEM_Big_Story_March_2019.pdf)
Ron Kociba, GM Powertrain chief engineer for the engine, summarized the layout decision with the phrase "We could've had a V-8." His team chose the inline six for its NVH (noise, vibration, and harshness) potential and other design advantages: a single cylinder head is cheaper to manufacture than two, and the hot and cold sides of the engine are almost totally demarcated, leaving room for heat-sensitive components such as the powertrain control module, which was mounted in the intake tract.[2](https://eu-assets.contentstack.com/v3/assets/blt7121b6ec5c11097b/blt568e1157ea176fc9/66224e6aeb73bb74c0aa253c/WardsAuto_OEM_Big_Story_March_2019.pdf)
Technology content was unusually high for a truck engine of the period. The engine uses dual overhead cams with four valves per cylinder, variable exhaust valve timing, an all-aluminum cylinder block and head, and electronic throttle control. GM positioned it as bringing premium passenger-car engine sophistication to the truck market, with power exceeding most competitors' V8s, and strong low- and midrange torque.[1](https://saemobilus.sae.org/papers/gm-powertrains-new-vortec-4200-inline-6-engine-2001-01-0331)
## The Vortec 4200 inline six
The 4.2-liter I6 displaced 4,160 cc from a 93 mm bore and 102 mm stroke, with a 10:1 compression ratio and specific output of 64 hp/L. Initial ratings were 270 hp at 6,000 rpm and 275 lb-ft (373 Nm) at 3,600 rpm, tested in the [GMC Envoy](https://www.edgepedia.org/gmc-envoy).[2](https://eu-assets.contentstack.com/v3/assets/blt7121b6ec5c11097b/blt568e1157ea176fc9/66224e6aeb73bb74c0aa253c/WardsAuto_OEM_Big_Story_March_2019.pdf) Ward's editors noted that the 270 hp figure exceeded essentially any V8 truck engine of the time, and that the engine pulled GM's midsize SUVs with abundant power.[2](https://eu-assets.contentstack.com/v3/assets/blt7121b6ec5c11097b/blt568e1157ea176fc9/66224e6aeb73bb74c0aa253c/WardsAuto_OEM_Big_Story_March_2019.pdf)
Output was later increased: GM's 2011 performance-parts catalog lists the engine at 285 hp and 276 lb-ft of torque.[6](https://media.gm.com/dld/content/Pages/presskits/us/en/Chevrolet/presskits/10pri/_jcr_content/rightpar/sectioncontainer_1/par/download/file.res/GMPP_2011_Catalog.pdf) A 2006 update added a mass air flow sensor and a complete internal redesign, raising power to 291 hp (217 kW) at 6,000 rpm and torque to 277 lb-ft (376 Nm) at 4,800 rpm, though SAE rating changes make year-to-year figures vary slightly.[7](https://www.gmsquarebody.com/threads/gm-4200-i6-swap.42402/)
The engine was named a Ward's 10 Best Engine in 2002, its first year, and again in 2003, 2004, and 2005, for four consecutive years.[2](https://eu-assets.contentstack.com/v3/assets/blt7121b6ec5c11097b/blt568e1157ea176fc9/66224e6aeb73bb74c0aa253c/WardsAuto_OEM_Big_Story_March_2019.pdf) • [4](https://www.centuryu.com/uploads/1/4/4/6/144698822/2006_trailblazer.pdf) • [8](https://www.theautochannel.com/news/2002/01/09/034358.html)
## The inline four and inline five
The Vortec 3500 inline five and Vortec 2800 inline four were derived from the Vortec 4200 and shared its all-aluminum construction, dual overhead camshafts, and four-valves-per-cylinder technology. The I-5 was rated at 220 horsepower (164 kW) and 225 lb-ft (305 Nm) of torque, and both engines powered the 2004 [Chevrolet Colorado](https://www.edgepedia.org/chevrolet-colorado) and GMC Canyon midsize pickups.[3](https://www.theautochannel.com/news/2003/01/08/152551.html) • [9](https://news.chevrolet.com/content/dam/company/no_search/heritage-archive-docs/vehicle-information-kits/chevrolet/2004-Chevrolet-Colorado.pdf) Kociba described the family approach directly: "The real key to these engines is that they're part of a carefully planned and developed inline family."[9](https://news.chevrolet.com/content/dam/company/no_search/heritage-archive-docs/vehicle-information-kits/chevrolet/2004-Chevrolet-Colorado.pdf)
The inline five also powered the [Hummer H3](https://www.edgepedia.org/hummer-h3), in 3.5-liter L52 form in 2006 and, from 2007, as the 3.7-liter LLR rated at 242 horsepower and 242 lb-ft (revised to 239 hp and 241 lb-ft for 2009).[10](https://www.gmhummer.com/h3-engines-i5-vs-v8/) The 3.7-liter I5 was also used in the Isuzu i-370.[11](https://static1.squarespace.com/static/5807b9379f7456a49c7a52d3/t/587ce2efbf629abac09fa06d/1484579568159/DIRECTIONS%2BFOR%2BGM%2BATLAS%2BVORTEX%2BINLINE%2B4-5-6_4.2_3.7_3.5_2.8_2.9L.pdf)
## Applications
The 4.2-liter I6 was used almost exclusively in the GMT360 midsize SUV platform and its extended-wheelbase GMT370 variants: the Chevrolet TrailBlazer and TrailBlazer EXT, GMC Envoy and Envoy XL, Buick Rainier, Oldsmobile Bravada, Isuzu Ascender, and [Saab 9-7X](https://www.edgepedia.org/saab-9-7x).[1](https://saemobilus.sae.org/papers/gm-powertrains-new-vortec-4200-inline-6-engine-2001-01-0331) • [3](https://www.theautochannel.com/news/2003/01/08/152551.html) • [5](https://chevromax.com/chevrolet-hub/guides/chevrolet-atlas-engine-family-explained-the-forgotten-inline-powerhouse/)
In the TrailBlazer, the engine delivered 0 to 60 mph in 7.9 seconds and the quarter mile in 16.3 seconds at 88 mph in [Car and Driver](https://www.edgepedia.org/car-and-driver)'s 2001 comparison test, best-in-test times for the group.[12](https://www.caranddriver.com/reviews/a15136458/chevrolet-trailblazer-ext-v-8-short-take-road-test/)
## End of production
Inline-six production ended in 2009 with the GMT360 platform, while the inline-four and inline-five continued in GM compact trucks through 2012, when the entire Atlas family was retired.[5](https://chevromax.com/chevrolet-hub/guides/chevrolet-atlas-engine-family-explained-the-forgotten-inline-powerhouse/) • [13](https://blog.consumerguide.com/forgotten-5-cylinder-engine/)
## References
1. [Sutter, T., Bolton, R., Fulton, K., Lee, J., et al., "GM Powertrain's New VORTEC 4200 Inline 6 Engine," SAE 2001 World Congress, March 5, 2001](https://saemobilus.sae.org/papers/gm-powertrains-new-vortec-4200-inline-6-engine-2001-01-0331)
2. [wardsauto-oem-bigstory-0319.indd](https://eu-assets.contentstack.com/v3/assets/blt7121b6ec5c11097b/blt568e1157ea176fc9/66224e6aeb73bb74c0aa253c/WardsAuto_OEM_Big_Story_March_2019.pdf)
3. [GM's Vortec 4200 I-6 Named 2003 Ward's 10 Best Engine, The Auto Channel, January 8, 2003](https://www.theautochannel.com/news/2003/01/08/152551.html)
4. [2006 Chevrolet TrailBlazer brochure feature text](https://www.centuryu.com/uploads/1/4/4/6/144698822/2006_trailblazer.pdf)
5. [What is the GM Atlas engine family and is it reliable?, Chevromax](https://chevromax.com/chevrolet-hub/guides/chevrolet-atlas-engine-family-explained-the-forgotten-inline-powerhouse/)
6. [GM Performance Parts 2011 Catalog](https://media.gm.com/dld/content/Pages/presskits/us/en/Chevrolet/presskits/10pri/_jcr_content/rightpar/sectioncontainer_1/par/download/file.res/GMPP_2011_Catalog.pdf)
7. [GM 4200 I6 swap?, GM Square Body forum](https://www.gmsquarebody.com/threads/gm-4200-i6-swap.42402/)
8. [Ward's AutoWorld Announces Ten Best Engines of 2002, The Auto Channel, January 9, 2002](https://www.theautochannel.com/news/2002/01/09/034358.html)
9. [2004 Chevrolet Colorado Restoration Kit, Chevrolet heritage archive](https://news.chevrolet.com/content/dam/company/no_search/heritage-archive-docs/vehicle-information-kits/chevrolet/2004-Chevrolet-Colorado.pdf)
10. [H3 powertrains: the inline-five against the 5.3 V8, GM Hummer Archive](https://www.gmhummer.com/h3-engines-i5-vs-v8/)
11. [Directions for GM Atlas Vortex Inline 4, 5 & 6 Cylinder engines](https://static1.squarespace.com/static/5807b9379f7456a49c7a52d3/t/587ce2efbf629abac09fa06d/1484579568159/DIRECTIONS%2BFOR%2BGM%2BATLAS%2BVORTEX%2BINLINE%2B4-5-6_4.2_3.7_3.5_2.8_2.9L.pdf)
12. [Chevrolet TrailBlazer EXT V-8, Car and Driver](https://www.caranddriver.com/reviews/a15136458/chevrolet-trailblazer-ext-v-8-short-take-road-test/)
13. [Inherent Imbalance: GM’s Forgotten 5-Cylinder Engine](https://blog.consumerguide.com/forgotten-5-cylinder-engine/)
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*Topic: Encyclopedia › Technology and the built world › Transport and spaceflight › Road transport › Trucks and trucking › Commercial trucks and manufacturers › Truck manufacturers, engines, and components*
*Initially written Sep 17, 2026 · Reviewed: Sep 30, 2026; Oct 15, 2026 · Edited: Oct 15, 2026; Oct 25, 2026 · Last review: Oct 15, 2026*
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License: Edgepedia Community License 1.0, https://www.edgepedia.org/edgepedia/license