Chevy 4.2 Inline-6: The Vortec Engine Everyone Forgot Existed

2006 GMC Envoy parked next to a graffiti wall

The popularity of various engine designs typically fades over time as technological advances provide more power, better fuel economy, or both. Flathead designs gave way to overhead valves, and inline cylinder arrangements morphed into V-shaped or horizontally-opposed layouts. However, sometimes the better engine layout depends on its manufacturing cost and versatility.

The automotive past is filled with legendary vehicles powered by inline six-cylinder engines. However, despite the recent popularity of the V6, the inline-6 could be making a comeback. One reason the V6 gained enough popularity to replace the I-6 was its similar layout to the V8 powering most high-end models over the last several decades. With the sunset of the V8 on the horizon and inline-four-bangers making their way into more base model offerings, the advantages of the inline-6 may tip in its favor.

Driving Line compares the GM 4.2-liter inline-six-cylinder Vortec 4200 to Toyota's 2JZ engine, one of the most powerful inline-6 engines ever put in a production car. While the production GM 4.2-liter Vortec didn't have as much power as Toyota's turbocharged 2JZ-GTE I-6, it provided up to 275 horsepower compared to the 230 horsepower of the naturally aspirated 2JZ-GE. The Vortec 4200 was used in General Motors' midsize SUVs built on the GMT360 platform from 2002 through 2009, including Chevrolets and Oldsmobiles.

Vortec 4.2 Inline-Six-Cylinder Performance

GM Vortec 4200 engine installed in a vehicle

General Motors introduced the dual overhead cam (DOHC) 4.2-liter inline-six-cylinder Vortec in 2002. The first production versions of the Vortec 4200 started out making 270 horsepower and 275 lb-ft of torque but soon advanced those horsepower numbers to 275 while keeping comparable torque values. That modest increase pales in comparison to the engine's potential as demonstrated in naturally aspirated promotional racing trucks that made 600 horsepower.

Upon the 4200 Vortec I-6's debut, MotorTrend reported the 256-cubic inch engine exceeded the one horsepower per cubic inch benchmark and made 90% of its torque between 1,600 and 5,600 rpm. Less than a year later the magazine tested a twin-turbocharged 4200 Vortec with 400 horsepower concept-engine placed in a Chevy Trailblazer as a show of force and a test of reliability. While the twin-turbo concept only made it to the prototype phase, it propelled the roughly 4,600-pound Trailblazer from 0-60 mph in the mid-5-second range with only 8.5 pounds of boost.

[Featured image by AnonymousOrc via

General Motors GMT360 Vortec 4200 Applications

Isuzu Ascender parked in a lot

The 4.2-liter Vortec came and went with the GMT360 platform encompassing the 2002 to 2009 model years. While GM-designed, the engine's popularity earned it a place in other manufacturers' lineups.

One primary recipient of the Vortec 4200, the Chevrolet Trailblazer, was produced from 2002 to 2009, all eight years of the Vortec 4200. The stretched Trailblazer EXT, with room for seven amongst its three rows of seating, only made the roster from 2002 to 2006.

Like the Trailblazer, the GMC Envoy graced showrooms from 2002 to 2009 with an XL version available the same years as the Trailblazer EXT. GMC also offered the unique 2004-2005 Envoy XUV with a retractable rear roof that allowed carrying taller cargo.

The Oldsmobile Bravada was another model based on the GMT360 platform and powered by the Vortec 4200 in 2002. It was discontinued when GM snuffed the Oldsmobile brand after the 2004 model year. Its replacement, the Buick Rainier, saw production from 2004 to 2007 and also carried the Vortec 4.2-liter in some trims.

Perhaps the most surprising use of the GM engine and platform design was in the Isuzu Ascender produced from 2003 to 2008. Like the Chevy and GMC models listed here, Isuzu also built an extended version of the Ascender that was available for the 2003 to 2007 model years.

[Featured image by IFCAR via

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