Chevy Geek

L99 vs. LS3 vs. LS7: Which Is The Best Engine For You?

Do you drive a GM/Chevy vehicle and wonder which L99, LS3, and LS7 engines are the best for you? All belong to the 4th generation of the small block engine family but have differences. If you drive an automatic vehicle, you likely have the L99 engine.

LS3 and L99 are nearly identical. But the latter features variable valve timing (VVT) and components of the Active Fuel Management (AFM) system. The LS7, on the other hand, is a larger and more powerful engine.

If you are still confused about what sets them apart, you have a reason to read this article. This is a head-to-head comparison of L99, LS3, and LS7

Read on for details!

What Is An L99, LS3, LS7 Engine?

What is an L99 Engine?

L99 V8 engine designed for automatic transmissions.

The 6.0-liter L99 V8 engine was produced by General Motors (GM) for high-performance vehicles. The L99 belongs to the GM’s 4th generation of V8 small block engines with a displacement of 6.2 liters and up to 8 cylinders assembled in a V structure.

The L99 was introduced in 2010, designed for automatic transmissions. The additional features included were the Active Fuel Management (AFM) and Variable Valve Timing (VVT), not available in the LS3 engines.

L99 produces a total power of 400 hp at 5900 RPM and a torque of 410 lb-feet at 4300 RPM. This is a reliable engine that should last the lifetime of the vehicle. However, longevity depends on many factors, including proper maintenance.

What is an LS3 Engine?

LS3 engine can produce 430 hp at 5900 RPM and between 420-428 lb-feet at 4600 RPM.

The 6.2-liter LS3 V8 engine is presently being produced by Chevrolet Performance. It is among the generation IV small engines used in high-performance manual transmission vehicles between 2007 and 2017. It is the successor to the 6.0-liter LS2 V8, with improved casting and larger bores.

The LS3 engine can produce 430 hp at 5900 RPM and between 420-428 lb-feet at 4600 RPM. LS3 has a good balance of performance and efficiency. The exhaust pipes were also redesigned for better airflow.

LS3 is a perfect engine if you are making a swap because of its greater power and reliability. It can go for as long as 200,000 miles or more if well maintained.

Read more: LS1 Vs. LS2 Vs. LS3 (With Comparison Chart)

What is an LS7 Engine?

The LS7 engine is famous for its consistency and smooth power delivery.

The 7.0L LS7 is a V8 engine manufactured by the GM to be fitted in high-performance vehicles. It has more power and torque than other small engines within the generation IV family. With LS7, you can get up to 505 hp at 6300 RPM and a torque of 470 lb-feet at 4800 RPM.

The LS7 is famous for its consistency and smooth power delivery. As one of the most powerful engines ever built, LS7 was designed for applications in the 6th generation Corvette Z06 and 427 Convertible and 5th generation Chevrolet Camaro Z/28.

The LS7 is a high-performance engine preferred by racers needing high-power builds. Overall, LS7 is a reliable engine.

L99 Vs LS3 Vs LS7 Comparison Chart

The L99 was introduced in 2010, designed for automatic transmissions.
LS3 is among the generation IV small engines used in high-performance manual transmission vehicles between 2008 and 2017.
The 7.0L LS7 is a V8 engine manufactured between 2006-2015 for high-performance vehicles.

Download the full comparison chart here

L99 Vs LS3 Vs LS7: Detailed Comparison

Generations and Years

L99, LS3, and LS7 engines belong to the generation IV engine family. The only difference is the year they were offered, with LS7 being the oldest, made between 2006 and 2015. It was followed by the LS3 engine, which was available from 2008 to 2017. L99 is the latest one with a slight modification of the LS3 making it suitable for automatic transmissions. The L99 was offered between the years 2010 and 2015.


Both LS3 and L99 engines have the same displacement of 6162cc (6.2L; 376.0 ci). This gives them enough performance for application in the Chevrolet Corvette, Corvette Grand Sport, Camaro SS, and Pontiac G8 GXP. 

The LS7 is a much larger engine with a displacement of 7008 cc (7.0L; 427.6 ci), offered in the Chevrolet Corvette Z06 from 2006 to 2013. It was also available for the Chevrolet Camaro Z28 from 2014 and 2015. Due to its large size, the LS7 engine produces more power and torque than LS3 and L99, as we will see in the next section.

Power Output

The LS3 gives you between 426 to 436 hp at 5900 RPM, L99 offers 400 hp at 5900 RPM, while LS7 is capable of a whopping 505 hp at 6300 RPM. If you are looking for the appropriate engine for your specific application, these parameters are crucial. 

As mentioned, the LS7 is recommended to racers needing more powerful builds.

Torque Output

The LS7 engine has the highest torque of 470 lb-ft at 4800 RPM. LS3 is the second in ranking with 420-428 lb-ft at 4600 RPM and L99 trails with a torque of just 410 lb-ft at 4300 RPM. 

From the power output and torque specifications, it is evident that all three engines were built for performance. There are just slight variations in the parameters, but they can be adjusted through upgrades.

Cylinder Bore Size

As expected, LS3 and L99 have the same cylinder bore size of 103.25 mm, while LS7 has a slightly larger cylinder bore of 104.8 mm. 

Once again, if you are building for more power, I recommend going for the engine with a large cylinder bore if you can afford it. In this case, LS7 is the best fit. A large cylinder bore unshrouds the valves and breaths better even at a high RPM. Hence, more power.

Piston Stroke Size


The piston stroke size is the same in LS3 and L99 engines. They both have a 92 mm bore, while LS7 has a 101.6 mm. The larger piston stroke size may be disadvantageous in LS7 engines, but they can equally last longer if done correctly. Longer strokes increase engine friction and cause stress on the crankshaft because of the high peak accelerations.

Compression Ratio

L99, LS3, and LS7 have compression ratios of 10.4:1, 10.7:1, 11.0:1, respectively. If you are building for fuel efficiency, choose the highest compression ratio. That is so because a higher compression ratio allows an engine to utilize more energy generated by the combustion process. The same combustion temperature can be achieved by using less fuel.

Block and Heads Material

The block and cylinder heads of the three engines are all made of cast aluminum. This material is preferred to cast iron and other metals for its high thermal conductivity and low weight. The engine cooling can be performed much faster and more efficiently. An aluminum engine block also uses lower-grade gasoline compared to the one made of cast iron.

This criterion may not be the best approach when deciding on the engine type to buy.

Fuel System

L99, LS3, and LS7 all use sequential fuel injection systems. As the name suggests, it is the fuel introduction in an internal combustion engine using injectors. Each injector is fired individually. The system is more fuel-efficient than a multiport system because the fuel mixture changes instantaneously. Fuel burns more efficiently since it is atomized as it passes through the cylinder. You will find the sequential fuel injection system in most modern engines.

Fuel Type


Premium fuel, gasoline with an octane level of 91 or greater, is required for LS7 engines. LS3 and L99 engines can also use the same fuel type, but that is not mandatory. They can operate well on regular or mid-grade gasoline. Fuel prices can vary greatly. So, when choosing one of the engines, pick one that runs on the fuel type that is readily available and affordable for you.

Oil System

The three engines have a dry-sump oil lubrication system. It uses two or more oil pumps and a separate oil reservoir to manage the lubricating motor oil throughout the engine block. That is opposed to the conventional wet-sump system that uses just one oil reservoir.


There is no interchangeability between the engines. Comparing LS7 and LS3 and L99, LS7 turns out to be unique with a larger bolt pattern and larger intake ports. That explains why direct swapping of the two is impossible.

LS3 and L99 are closely related, but you cannot swap them. The two engines are designed for different purposes. L99 is best for automatic transmission, while LS3 is suited for manual transmission. You can, however, convert L99 to LS3 and vice versa using special kits. You can interchange the two after conversion. If done correctly, you can get more power and performance.


The GM LS3 6.2L engine costs about $6,500 and L99 about $7,000. LS7 is the most expensive, costing about $12,700. Please note that these costs are just estimates and can significantly change depending on the engine model and year of make. You can check accurate prices of complete engines on eBay and other sellers.


Both LS3 and LS7 come from General Motors, but which one is the most reliable? The engines are powerful and have high longevity. However, LS7 has an advantage with a peak of 505 hp and 470 lb-ft in torque.

The L99 engine is equally high-performing, but it is not as powerful as the first two mentioned. You will have to sacrifice a few horsepower and torque if you choose it over the others.

Common Problems

LS3 has the same faulty rings experienced by all the LS engine series. This problem should be fixed on time before it leads to high oil consumption or engine blow-by. The problematic piston ring issue usually results if you mod the engine.

Also, the small and compact size of the LS3 engine makes it challenging to maintain. Lifters and other replaceable components are inaccessible.

The commonly reported problem of the LS7 engine is associated with the oil system due to cavitation problems. The good news is that you can easily replace it with a new one. Also, swapping LS7 engines can be expensive, especially when looking for a compatible transmission system.

L99 engines have lifter problems due to the displacement on demand (DOD), which usually happens when you convert LS3 to L99.

A video about Chevy LS engine.


Choosing the best engine type for your application can make all the difference. The LS3, L99, and LS7 are closely related but have noticeable differences. 

We’ve looked at how they differ in performance and other attributes. The LS7 turns out to be the best among the engines compared here. You may consider it for high-power applications.

Read more: Stage 1 Tune Vs. Stage 2 Tune Vs. Stage 3 Tune: Similarities And Differences


  • Randy Worner

    My name is Randy Worner and I am the founder of I have been working on cars and trucks for almost 45 years. For the last 36 years I have taught Automotive / Diesel Technology classes for UTI, Snap On Tools, Chrysler, Pepboys, Lone Star College, NAPA and TBC Corporation. I also own a technical writing company known as Supreme Technical Services. It is ASE Gold Seal certified and Blue Seal Certified Author of auto/truck repair information.

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