LQ4 vs LQ9 Engine – Know Actual Difference Between Them

LQ9 vs LQ4

LS engines have gained quite the hype in the market for their performance. These engines have gained much popularity due to their capability of handling modifications.

LQ9 and LQ4 are the two most common and sought-after LS engines currently. The hype for these engines has increased sales in junkyard and online marketplaces for a very fair price.

So, do you want to jump on the LS engine trend? If so, then you have come to the right place. Today we will talk about the two in-demand engines.

Read on to know more about the characteristics of LQ4 vs. LQ9.

What is LQ4?

The LQ4 is one of the very first luxury sport truck engines, which was introduced in 1999. It was also called the Vortec 6000. General Motors introduced it as a 3rd generation, 6.0L small block engine.

This specific engine was used in many General Motor vehicles from the year 1999 to 2007. The engine is popular due to its variety of possible modifications. LQ4’s 8th digit of the VIN code was U.

Vehichles like the Chevrolet Subarban (1999-2001), GMC Sierra 2500(1999-2004). GMC Savana (2003-2007), Hummer H2 (2003 and 2007), and many others used the LQ4.

The LQ4 has a compression ratio of 9.4:1. Its horsepower rating is from 300hp to 330hp and has a torque rating of 360 to 370 ft/lbs. depending on the cylinder head used. So, we can say that this engine can definitely work well with different modifications.

Now, let’s get onto some small details about the LQ4 engine.

Block Specs:

  • The LQ4 engine block is made of iron.
  • While the bore diameter of LQ4 is 4 inches, and the bore spacing is 4.40 inches.
  • The stroke is 3.622 inches, and the deck height is 9.23 inches to 9.24 inches. And it has a 6-bolt main cap style.

Rotating Assembly Specs:

  • The piston material for LQ4 is Hypereutectic Cast Aluminum Alloy. Piston style is dished and has a volume of +6.7cc.

Cylinder Head Specs:

  • The cylinder head’s material was Iron in the year 1999 and 2000. From 2001 to 2007, the material was changed to aluminum.
  • Combustion chamber volume of LQ4 is 71cc. The intake port shape is cathedral.
  • The exhaust port shape of the cylinder head was oval in 1999 and 2000. It was changed to a D-port shape from 2001 up to 2007.

Cam Specs:

  • LQ4 has a 3-bolt cam gear attachment. 
  • The lobe separation angle was 114 ° (1999-2000) and later changed to 116 °s till the year 2007.

Other Specs:

  • The throttle control of LQ4 was cable operated in 1999-2002 and was changed to electronic and drive by wire in 2003-2004.
  • The valvetrain’s lifter style was hydraulic roller with a body diameter of 0.842 inch.
  • And the fuel injector flow is 24.9 lbs. per hour.

This is all the insight you need to know about the LQ4. To learn about the LQ9, keep on reading.

What is LQ9?

The LQ9 was introduced in the year 2002 by General Motors. It was said to be an upgraded version of the LQ4 as it was in the same LS family. People also know it as the Vortec HO 6000 or the VortecMAX.

Flat piston and floating wrist pin rods made the LQ9 a higher output version of LQ4. The 8th digit of LQ9’s VIN code is N.

In the year 2002, LQ9  was initially introduced for the Cadillac Escalade but later was used in various General Motors pickups. This engine was used in the Cadillac Escalade EXT (2002-2006), Chevy Silverado SS (2003-2007), GMC Sierra 1500 Classic Vortec Max (2006-2007), and many other models of Chevy, Cadillac and GMC.

The compression ratio of LQ9 is 10.1:1. Due to such a compression ratio, LQ9 has a higher horsepower rating which is 345 hp. And it has a torque rating of 380ft./lbs. So let us learn a little more about the LQ9 engine’s specifications.

Block Specs:

  • Much like the LQ4, the LQ9’s block material is also iron. The bore diameter is 4 inches, and the stroke is 3.622 inches.
  • The bore spacing is also the same as the LQ4’s bore spacing. And the main cap style is 6 bolts.

Piston Specs:

  • The LQ9’s piston style is flat-topped.
  • This style of the piston increases the compression ratio and horsepower of the engine.
  • The piston volume is 0cc.

Cylinder Head Specs:

  • LQ9’s cylinder is also made up of aluminum. It has a combustion chamber volume of 71cc.
  • The intake port shape is also cathedral, and the exhaust port shape is D-Port.

Cam Specs:

  • It has a 3-bolt cam gear attachment with a lobe separation angle of 116°.
  • The horsepower of the engine can be increased significantly by making modifications with the right cam shift kit.

Other Specs:

  • The LQ9 has a throttle body of 80mm. The throttle control is electronic and drive by wire.
  • LQ9’s fuel injector flow is 25.2 lbs per hour.
  • The valvetrain specifications LQ9 are the same as the LQ4’s.
  • The engine block alone weighs around 100 pounds. However, with modifications, the weight can increase by over 200 pounds.

The Similarities Between LQ9 and LQ4

Like we mentioned before, both the LQ4 and LQ9 have many similarities. They are from the same LS family. So, before we talk about what makes them different, let us have one last look at what you will find common between the two:

  1. Visual Similarities: Both the LQ9 & LQ4 are visually similar. Their distinctive characteristics are situated inside the engines, so it is very hard to tell them apart from the outside. The length, width, and diameter specifications of most parts of the engines are also the same.
  2. Type of Engine: They both have the similar engine type which is the 6.0L small block engines. With smaller bores and shorter strokes, they make smaller displacements.
  3. Efficiency: These engines are built to handle a range of modifications so that the horsepower can be increased by a significant amount.
  4. Availability: You will find these two engines available in the market along with their components.

LQ9 vs LQ4: How Can You Identify Them?

We have talked about the LQ9 and LQ4’s specs and similarities. But how do you tell the difference between them? How can you identify one from the other? Now we will talk about that.

  1. Check VIN code: Check the 8th digit of the VIN code on these engines. For LQ4, it will be U, and for LQ9, it will be N. Now, if you do not have the VIN code, read on to know how else you can identify them.
  2. Check the Piston: For this, you have to remove the cylinder head and the spark plug and inspect the cylinder with the help of a borescope. If the cylinder is flat, then it is LQ9. If it is of a dished shape, then it is LQ4.
  3. Price: The LQ4 and LQ9 engines cost around $1500 for the engines only. Modifications have separate costs. But the LQ9 has a premium of $1000 for the engine only.
  4. Transmission: Vehicles with 1500 chassis get a transmission of L460E, while vehicles with 2500 chassis get L480E. Although LQ9 provides higher output than LQ4, the Lq9 comes with 1500 chassis vehicles. So, you will get a transmission of L46OE. And that cannot be changed electrically.

We hope the aforementioned information helps you identify between the LQ4 & LQ9.

Things You Should Consider While Purchasing the Engine

Consider this a brief buying guide to help you with your purchase decision. It is very important that you do your homework before making a purchase. Swapping an LS engine in your vehicle may be very exciting.

So here are a few things to keep in mind while purchasing the engine:

  1. Make sure you take the opportunity to hear the engine run.
  2. Test the compression.
  3. Inspect the Spark Plugs.
  4. Learn to identify the engines.
  5. Inspect the Exhaust Manifold Bolts.
  6. Ask questions from the buyer without any hesitation.
  7. Try to purchase from a salvage yard that offers warranty.

Without proper homework, there is a chance you may end up making the wrong purchase. So, educate yourself on the product so that you can make a good inspection before the purchase.

So, Which One Should You Choose?

Although the LQ9 has higher compression and horsepower than the LQ4, you can say the difference is somewhat trifling. Both engines have similar designs giving you the same visual appearance.

Both the LQ4 and LQ9 have gained much popularity due to their performance. Due to their similarities, they are also swappable, and you can use them in most SUVs and trucks.

These modern-day engines will give you value for your money no matter which one you choose.

But now that you know the characteristics and distinctions of the LQ9 vs LQ4, you can now determine which engine is more suited to your liking and budget. Happy Shopping!

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