Inherent Imbalance: GM’s Forgotten 5-Cylinder Engine (2022)

Inherent Imbalance: GM’s Forgotten 5-Cylinder Engine (1)

The LLR Vortec 3700 is one version of the only 5-cylinder engine General Motors has ever made available in the U.S.

Americans tend to enjoy their engine cylinder counts in even numbers. Engines of 4-, 6-, and 8 cylinders have powered an overwhelmingly large majority of the vehicles ever sold in the U.S, and for good reason.

The basic design of the 4-cycle engine favors even cylinder counts, at least when it comes to balance and smoothness, with the classic inline 6-cylinder configuration inherently the smoothest of all.

Still, there are reasons a carmaker might stray from the tried and true when it comes to engine layout. For purposes of economy, American consumers have occasionally been able to purchase vehicles powered by 3-cylider engines. The Ford Fiesta, for example, can be had with that maker’s EcoBoost 1.0-liter mill, which employs just 3 pistons.

More common, though hardly common by absolute standards, is the 5-cylinder engine.

Inherent Imbalance: GM’s Forgotten 5-Cylinder Engine (2)

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Chevrolet markets most of its non-diesel truck engines under the Vortec banner.

Though more prone to vibration than any even-numbered engine configuration, the inline 5-cylinder does offer certain design advantages. For starters, it’s easier to package than an inline 6-cylinder, which, for obvious, reasons is longer, and thus more difficult to wedge between a vehicle’s firewall and grille. This issue has become more profound in recent years as hoodlines have lowered, leaving less space in the engine bay. It was specifically to allow for more aerodynamic vehicle designs that Mercedes-Benz famously began moving to V6 engines back in 1997.

Inline 5-cylinder engines are also usually less costly to produce than are V6 mills. While a V6 has cylinders arrange in two banks, and thus requires twice the milling, any inline engine has its cylinder bores aligned in a single straight line, which simplifies manufacturing. Additionally, with two cylinder banks, a V6 requires two cylinder heads, which adds cost, weight, and complexity to the engine.

It’s the German carmakers that have most readily embraced the 5-cylinder engine, with BMW, Mercedes-Benz, and Volkswagen (including Audi) each offering 5-pots in the U.S. at some point in time. Between 2000 and 2005, VW also offered to its European customers the VR5, the only V5 engine ever to find its way under the hood of a modern production vehicle.

Other 5-cylinder engines include a 2.5-liter Honda plant that was available in the Acura Vigor. Ford of Europe sold an inline 5 for a while, a version of which powered the previous generation of the Focus RS. Volvo still produces 5-cylinder engines, though it is in the process of switching its entire lineup to turbocharged 4-cylinder engines. Land Rover also offered a 5-cylinder diesel mill in several of its models over the years.

Fiat and European engine builder VM Motori have supplied a number of 5-cylinder diesel engines to different carmakers over the years, with those powerplants ending up in various stray brands and models.

But, to the best of our recollection, no domestic maker has ever built and sold a 5-cylinder engine in the U.S. Well, not ever. There was this one time…

General Motors dubbed it the Atlas engine, and it was a family of inline engines designed to be light weight, fuel efficient, and easy to package.

The Atlas family of engines included a hulking 4.2-liter six, a workhorse 2.8-liter four, and, oddly enough, a 3.5-liter 5-cylinder.

Inherent Imbalance: GM’s Forgotten 5-Cylinder Engine (3)

Though not a production model, the 2002 Chevrolet Bel Air Concept was pitched to the public as being powered by a 3.5-liter 5-cylinder engine. Whether or not a running example of the vehicle ever existed, we consider it the first vehicle powered by the Atlas 5-cylinder engine, and the only car.

(Video) Inline 5 Cylinder Engine - Explained

The first Atlas engine made its debut in 2002 in GM’s new GM360 and GM370 midsize SUVs. Marketed as the Vortec 4200, the 4.2-liter six proved a capable base engine for these burly trucks, which included for ’02 the Chevrolet Blazer, GMC Envoy, and Oldsmobile Bravada. Subsequent model years would bring the Buick Rainier, Isuzu Ascender, and Saab 9-7X, all of which were based on the same GM architecture and would be offered with the Atlas 6-cylinder engine.

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It was not until 2004 that the Atlas 4- and 5-cylinder engines would come into play. For ’04, Chevrolet and GMC rolled out redesigned compact pickups, both of which would be powered exclusively by Atlas engines.

The Chevrolet Colorado and GMC Canyon were offered with the 2.8-liter four (Vortec 2800) as the base engine, with the 3.5-liter five (Vortec 3500) as the optional mill. The big six would not be offered in these trucks.

On paper, the Atlas engines looked like good fits for the little pickups. The 4-cylinder engine was good for 175 horsepower, while the five cranked out a healthy 220. One wonders, however, if traditional truck buyers balked at purchasing a 5-cylinder truck, when the previous generation of these vehicles had been available with a burly 4.3-liter V6.

The 5-cylinder engine would go on to be optional in an Isuzu clone of the Colorado and Canyon, the i-Series. The compact Hummer H3 SUV would also come standard with the Atlas 5-cylinder.

Note that for 2007 the Atlas 4- and 5-cylinder engines would receive a bump in displacement to 2.9 liters and 3.7 liters, respectively. Horsepower for the mills jumped accordingly, to 185 and 242, respectively. With the size increase came the predictable name changes to Vortec 2900 and Vortec 3700.

The Atlas 5-cylinder engine would survive through 2012, when GM’s compact trucks were redesigned and treated to a new series of base and optional engines. With that the entire Atlas family of engines was retired, with it the only 5-cylinder motor any U.S. maker has built and sold in the States.

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Amassed here are all the vehicles ever to be offered with the Atlas 5-cylinder engine. Let us know if you ever spent time with one of them.

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GM 5-Cylinder Engine

2004-2012 Chevrolet Colorado and GMC Canyon

Inherent Imbalance: GM’s Forgotten 5-Cylinder Engine (4)

2007 Chevrolet Colorado

Inherent Imbalance: GM’s Forgotten 5-Cylinder Engine (5)

2011 GMC Canyon

The Colorado and Canyon were the first production vehicles to be powered by the Atlas 5-cylinder engine. The engine was optional on most versions of the Colorado and Canyon, with the Atlas 2.8-liter 4 serving as the standard mill. For 2007 the both the 4- and 5-cylinder engines received displacement and power bumps, and would then go on unchanged through 2012 when the trucks were redesigned. Curiously, though a 6-cylinder engine was never offered in these trucks, a 5.3-liter V8 was made available beginning in 2009.

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2006-2008 Isuzu i-280/i-350 and i-290/i-370

Inherent Imbalance: GM’s Forgotten 5-Cylinder Engine (6)

2007 Isuzu i-370

When Isuzu decided to get back into the pickup truck business for 2006, it did so in the easiest manner possible: It simply bought trucks from General Motors and slapped its own grille on them. Thus was born one of the messiest bowls of model-name alphabet soup ever to be thrust upon the American car-buying public. By basing its new trucks’ names on their engine displacement, Isuzu was forced to change those names when the engines were updated for 2007. Thus what were the Isuzu i-280 and i-350 for 2006 became the i-290 and i-370 for 2007, not that consumers cared all that much. Apart from the grilles, these small trucks were identical to the Chevy Colorado, with only stickers–not badges–used to denote trim levels. Needless to say, the i-Series trucks were the only 5-cylinder Isuzu products ever sold on the U.S.

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2006-2010 Hummer H3

Inherent Imbalance: GM’s Forgotten 5-Cylinder Engine (7)

2006 Hummer H3

The lone socially responsible member of the short-lived Hummer family was also the only model to be made available with a 5-cylinder engine. As the H3 was based on Chevrolet Colorado/GMC Canyon architecture, it only made sense that the drivetrain components would also be shared. The H3 came standard with the 5-cylinder plant, with a 5.3-liter V8 coming along as standard later in the production run.

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Written by: Tom Appel on August 2, 2017.on January 19, 2021.


How is a 5-cylinder engine balanced? ›

Inline 5 Cylinder Engine - Explained - YouTube

Is a 5-cylinder engine a good engine? ›

From a driving experience, five-cylinder engines have the best aspects of four and six cylinder engines. They generate more power and torque than four cylinder engines, while maintaining the fuel economy and “pep” of smaller four cylinder engines.

Does GMC make a 5-cylinder engine? ›

with the fuel economy of a 4-cyl., for its redesigned 2004 Chevrolet and GMC midsize pickup trucks. According to Ward's Engine and Vehicle Technology Update, the Vortec 3500 I-5 is the latest addition to GM Powertrain's Vortec inline engine family.

Did the Chevy Colorado come with a 5-cylinder engine? ›

Two engines are available in the Chevrolet Colorado, a 2.9-liter four-cylinder that makes 185 horsepower and 190 pound-feet of torque or a 3.7-liter five-cylinder that makes 242 horsepower and 242 pound-feet of torque.

Are 5 cylinder engines rare? ›

Five-cylinder is a much less common engine type that only a few manufacturers have ever embraced. Audi really made the five-cylinder catch on with the mighty Sport Quattro, and the VW Group has been doing good things with these engines recently.

Which engine is most balanced? ›

The most naturally balanced engine in its basic state is an Inline-6 cylinder. Due to the timing of the pistons, the six cylinders move in pairs but fire on alternating cycles. This results in a uniform and constant gap between each cylinder movement.

Why do 5 cylinder engines sound so good? ›

The distinctly characterful sound of a five-pot is a direct cause of its odd-numbered design. The exhaust pulses leaving the combustion chambers overlap each other due to the angles at which the pistons meet the crank, which creates the unique rasp-over-burble tone.

Why do 5 cylinder engines exist? ›

The straight-five engine or inline-five engine is an internal combustion engine with five cylinders aligned in one row or plane, sharing a single engine block and crankcase. The justification for a five-cylinder engine is that it is almost as compact as an inline-four, and almost as smooth as a straight-six engine.

What Chevy truck has a 5 cylinder engine? ›

2006-2010 Hummer H3

The lone socially responsible member of the short-lived Hummer family was also the only model to be made available with a 5-cylinder engine. As the H3 was based on Chevrolet Colorado/GMC Canyon architecture, it only made sense that the drivetrain components would also be shared.

What did the GM 4200 come in? ›

LL8 (Vortec 4200)

It was the first Atlas engine, and was introduced in 2002 for the Chevrolet TrailBlazer, GMC Envoy, and Oldsmobile Bravada. The engine was also used in the Buick Rainier, Saab 9-7X, and Isuzu Ascender.

How good is the Vortec 4200 engine? ›

The Vortec 4200 is unquestionably the most refreshing, entertaining and powerful “base” engine in the light-truck market. Its refinement befits a luxury car, its brawny side unveiled only when you need to use it like a truck's meant to be used.

Does TrailBlazer come with 5 cylinder engine? ›

Engines. The TrailBlazer comes with an all-aluminum 4.2 L Atlas LL8 inline-six engine that produces 203.5 kW (273 hp; 277 PS) and 376 N⋅m (277 lb⋅ft) of torque as standard, or an optional aluminum small-block 5.3 L V8 engine that produces 225 kW (302 hp; 306 PS) and 447 N⋅m (330 lb⋅ft) of torque.

Which engine configuration is the smoothest? ›

The straight-six is Inherently balanced. The layout combined with its firing order leads to essentially the smoothest engine out there.

Is the Vortec 3500 a good engine? ›

The Vortec 3500 I5 (and its sister engines) have proven to be fairly reliable and trouble-free — with one exception. The factory valve seats in some 2004 to 2006 SUVs with the 2800 or 3500 engines apparently were not up to the normal hardness standards and may experience a premature wear problem.

How many cylinders is a Vortec 4200? ›

Inside Chevrolet's Vortec 4200 Inline-Six Cylinder

The engine is called the Vortec 4200 I6 and was initially created for General Motors' midsize sport utility vehicles.

Do 5 cylinder engines exist? ›

Or is it the performance of a four with the fuel economy of a six? The inline five-cylinder engine can be any of those things. Manufacturers from Acura to Volvo have experimented with this odd-numbered design—with varying degrees of success—since the 1974 Mercedes-Benz 240D.

Is there a 7 cylinder engine? ›

Only one straight-seven engine for land propulsion is known to be in production, the AGCO Sisu 7-cylinder diesel engine. This engine configuration was chosen because of size, parts commonality, and power range issues.


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