LY6 Vs. LQ9 – What are The Differences?

It is no secret that the engine is a crucial car component, with many auto pundits equating its functionality to the human heart. Several types of engines exist, with varying specifications to meet different applications. The LY6 vs. LQ9 discussion looks at two types of engines from GM.

The two engines share several similarities, and an inexperienced eye may find it challenging to differentiate them. A thorough review of the two GM products will reveal their specs and, ultimately, their differences.

LY6 Vs. LQ9 Engine

LY6 Engine

We start our review by focusing on the LY6, a 4th Generation 6.0-liter V8 engine built for SUVs and trucks by GM between 2007 and 2010. Also marketed as the Vortec 6000, the LY6 is a powerful engine with excellent specs that make it ideal for engine swaps in the auto-tuning scene.

The LY6 replaced the LQ9 and was among the debutants of the 4th Generation, together with LY2 and LY5. This engine sports aluminum cylinder heads, which help reduce its weight and boost heat dissipation, improving performance and efficiency.

The LY6 engine has a horsepower rating of 364 and torque of 383 ft./lbs. The added torque and horsepower are the fruits of the Variable Valve Timing (VVT) feature, besides improved fuel economy and emission control. The engine relies on a sequential fuel system for ample fuel delivery to each cylinder. The outcome is better fuel efficiency and controlled emissions.

LY6s are part of the LS family and are closer to the LS3 engine. Similarities include both being small block 4th Generation V8s, a high displacement value in the 6.0-liter range, and aluminum cylinder heads.

LY6 Engines Vehicles

Several GMC model trims left the assembly line with the LY6 engine under their hoods. Most of the cars had corresponding production years to the LY6. Vehicles sporting the LY6 as their original engine include:

  • 2007-2010 Chevrolet Silverado 2500 HD and 3500 HD
  • 2007 -2009 Chevrolet Suburban 2500
  • 2008- 2009 Chevrolet Express 2500 and 3500
  • 2007- 2009 GMC Yukon XL 2500
  • 2008- 2009 GMC Savana 2500 and 3500
  • 2007- 2010 GMC Sierra 2500 HD and 3500 HD

You may find the LY6 in other models as a result of aftermarket tuning, targeting a high torque value.

LQ9 Engine

The LQ9 is a 3rd Generation small block engine from GM, intended for its trucks due to its impressive performance. This V8 engine has a 6.0-liter displacement, and several trucks featured it between 2002 and 2007. The LQ9 had a name change in 2006 and went by VortecMax, and was marketed as Vortec HO 6000 during its production years.

The LQ9 engine is an iron-cast built with aluminum cylinder heads: the iron-cast body is durable. A standout thing about this engine is its performance, with an output of 345 horsepower and torque of 380 ft./lbs. It owes the figures to its high-compression flat-top pistons. The excellent power ratings explain its use on heavy-duty vehicles.

This engine has a high compression ratio of 10.1:1, a reason behind its excellent performance, though it may require high-octane fuel. Its sequential fuel system ensures adequate fuel delivery to each cylinder, resulting in optimal combustion.

LQ4 vs. LQ9, what is the difference? These two 3rd Gen LS engines share similarities like a cast-iron build and displacement value. LQ9 has flat-top pistons, while LQ4 has dished pistons. The LQ9 also has a higher compression ratio than its counterpart; thus, more power. In short, the LQ9 is a high-output version of the LQ4.

LQ9 Engines Vehicles

The LQ9 engine was initially designed for Cadillac, though it was featured in many other GM trucks and SUVs. The following are some models that sport the LQ9 as a stock engine.

  • 2002- 2006 Cadillac Escalade AWD and 2006 Cadillac Escalade 2WD
  • 2002- 2006 Cadillac Escalade EXT
  • 2003- 2006 Cadillac Escalade ESV
  • 2003-2007 Chevrolet Silverado SS
  • 2004-2006 Chevrolet Silverado HO edition
  • 2004- 2006 GMC Sierra HO edition
  • 2006- 2007 GMC Sierra 1500 Classic VortecMax
  • 2006-2007 Chevrolet Silverado Classic VortecMax

What Is the Difference Between LY6 And LQ9?

LQ9 vs. LY6 comparisons reveal that they are similar in many ways, such as having eight aluminum cylinder heads, an iron-cast body, and a 6.0-liter displacement. Nonetheless, some specs differ, as shown in the table below.

Engine Specification LY6 Engine LQ9 Engine
Production Years 2007- 2010 2002- 2007
Material Cast iron with aluminum cylinder heads Cast iron with aluminum cylinder heads
Displacement 6.0 liters 6.0 liters
Compression Ratio 9.6:1 10.1:1
Horsepower 364 345
Torque 383 ft./lbs 380 ft./lbs
Bore Diameter 4 inches 4 inches
Stroke Length 3.622 inches 3.622 inches
Bore Spacing 4.4 inches 4.4 inches
Deck Height 9.24 inches 9.23- 9.24 inches
Piston style Dished with valve reliefs Flat top
Piston Volume +6.7cc 0cc

The primary difference between LY6 and LQ9 is their compression ratio, with the latter having a higher value. While a higher compression ratio translates to a higher output, we see that LY6 is more potent than LQ9, though by a slight margin.

The other contrast point between the two engines is their piston style. LY6’s pistons have a dished design with valve reliefs, whereas LQ9 has flat-top pistons, contributing to its great compression ratio. Moreover, LY6 has variable valve timing, while its older counterpart lacks it. The variable valve timing feature boosts the LY6’s performance and fuel efficiency, explaining why it is more powerful than the LQ9.

The LY6 takes over the LQ9 with its rectangular port heads, allowing more airflow due to their size.  LQ9 engines have smaller cathedral port heads, contributing to a high compression ratio.

Still, on the LS engine differences, we can bring another player into the equation, the L96. It leads us to the LY6 vs. L96 comparison, where we deduce that both are 4th Generation LS engines, with the latter being around from 2010 to 2020.

The two engines have a 6-liter displacement and variable valve timing feature. The compression ratio is almost similar, at 9.7:1 for L96 and 9.6:1 for LY6. What about L96 vs. LQ9? Noticeable differences include LQ9’s higher compression ratio and lack of VVT.


Is The LY6 A Good Engine?

The LY6 is a 3rd Generation LS engine manufactured from 2007 to 2010 for GM trucks and SUVs. It has several appealing attributes, such as its power output. It is capable of 383 ft./lbs torque and a horsepower of 364.

This engine has a sturdy frame, with cast iron being its main material, enhancing its resiliency. The robust and lightweight aluminum cylinder heads improve heat dissipation and overall efficiency.

The LY6’s sequential fuel injection system promotes even fuel distribution to each cylinder. The result is efficient combustion and excellent fuel economy. This engine is compatible with several transmission units; hence, its wide use in auto-tuning. Furthermore, its parts are readily available.

What Does an LY6 Come In?

The LY6 was a stock component for some GM models that came out between 2007 and 2010, this engine’s production years. The models include the 2008 to 2009 GMC Savana 2500 and 3500, the 2007 to 2010 Chevy Silverado 2500 HD and 3500 HD, and the 2007 to 2009 GMC Yukon XL 2500.

Is The LQ9 Engine An LS?

LS refers to GM small-blocked V6 and V8 engines manufactured in five generations, with plans for a sixth. The LQ9 is a 3rd Generation LS engine produced between 2002 and 2007 and was originally meant for Cadillac. It is an upgrade of the LQ4 engine and boasts impressive performance, supported by its remarkable compression ratio.

Is The LQ9 A Good Engine?

The LQ9 is a Third Generation LS engine from GM, designed for trucks, SUVs, and vans. Its main selling point is its power output, owing to its high compression ratio. The power makes it suitable for heavy-duty and performance-oriented cars.

The engine block is durable, iron being the primary material. Parts like cylinder heads feature heavy-duty aluminum. This engine is versatile, evident from its compatibility with various transmission systems.

LQ9 has solid aftermarket support due to its popularity. Getting spare parts is a walk in the park. The engine’s sequential fuel injection unit guarantees optimum combustion, translating to power and fuel economy.

Is The LQ9 Iron or Aluminum?

Most LS engines, including the LQ9, have a cast-iron block, which is durable and highly resistant to wear and tear. It has aluminum parts, like the cylinder heads. Aluminum is ideal for cylinder heads as it is light, supporting fuel efficiency, acceleration, and handling. This material’s conductivity helps with heat dissipation, protecting the engine from degradation courtesy of heat buildup.

How Do I Know If My 6.0 Is LY6 Or LQ9?

It may be quite challenging to distinguish an LY6 engine from LQ9, especially for an inexperienced eye. You can start by checking the engine code, usually labeled on the engine’s front or side. You may also refer to the vehicle’s manual for your engine’s specs.

The other way of determining your engine type is by checking your Vehicle Identification Number (VIN). The eighth character on the VIN provides information about the engine. For LY6, the character is K, while for LQ9 is N.

Final Words

The LY6 vs. LQ9 review brings to light several things, such as their specs, similarities, and differences. Key takeaways include both being LS engines, though varying generations. LQ9 is a powerful engine due to its high compression ratio. LY6 is also powerful and efficient, supported by the VVT add-on.

The best pick from the two depends on several factors. For instance, the LQ9 is suitable for heavy-duty applications, while the LY6 is ideal for performance-oriented settings. You can also tune up the engines to match your preferences.


Hi there, I am R. Hasan Tito, a mechanic, and owner of this website. My friend and I created this website to share our knowledge, expertise, and experience with our fellow mechanics' community and car users. I am a specialist and certified automotive mechanic (Both Heavy Commercial and Private Cars). I worked as a Mechanic and Mechanic Supervisor for over fifteen years at Global Rebound Automotive companies - Toyota, TATA, BMW, Nissan, TVs, and Others. Now, I enjoy my new role of leading a team of automotive experts (in their respective fields) and publish new content on a regular basis on my website and social media.

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