LS3 vs. LS7 Engine: What’s the Differences ?

The engine is the heart of the car: this is a common saying you will find in the auto scene. Over the years, many standout engine models have been gracing the vehicle manufacturing industry. One of them is General Motors’ LS small-block engine series.  There are several engine models under this series, but our focus lies on the LS3 vs. LS7 subject. It brings to play two high performers, seeking to see which of them is the best.

If you want to know about their features and functionality, hang on as we comprehensively look at each of them.

LS3 Engine

LS3 Engine
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The LS3 engine is a 4th generation small block engine from General Motors. It debuted in 2008 as the base engine for the 2008 Corvette models. The LS3 is the to-go remanufactured engine for most Chevrolet supercars due to its excellent performance. LS3 vs. LS2, is there a relation? Many auto-engineering pundits view the LS3 as an updated version of the LS2. It features an aluminum block like the LS2 but with a larger bore, translating to a higher displacement. Additionally, this engine features a more robust casting, translating to a durable build.

Ever since it came out, it was the standard engine for GM’s high-performance vehicles like the Camaro, Pontiac G8, and Corvette.  The LS3 has a displacement of 6.2 liters, relying on the sequential fuel injection system. When the LS3 graced the scene, it had a horsepower of 430 and 424 pounds per foot in torque. These are potent values, which explain its extensive use in muscle and power cars. Some car manufacturers modified the engine, giving it a power boost. At the moment, you can find varieties of the LS3 with an output of 436 horsepower.

Furthermore, this V8 assembly has high-flow cylinder heads that allow for ample airflow, giving a significant horsepower band. Additionally, it has a high-flow intake manifold for compatibility with the cylinder heads. Its 58X ignition unit sees that the ignition timing is accurate. It works with the crankshaft ring and sensor, giving an accurate reading of the crankshaft position.  The timing precision improves the engine’s performance and fuel economy.

The LS7 Engine

LS7 Engine
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The LS7 has a legendary status in the auto-mechanic scene due to its excellent performance. It is among the few General Motors’ handmade engines, making its debut in 2006, earlier than the LS3. Similar to the LS3, this fourth-generation GM engine is an LS2 update. It has an aluminum block but a larger bore. The bore is quite the same size as the LS7, giving it a higher displacement of 7 liters. Another standout feature of the LS7 is the use of aluminum and cast steel, translating to durability and a light frame.

A look at the LS7 engine in Reddit discussion rooms and you see many enthusiasts describing it as notoriously powerful. Evidence of its immense power is its 505 horsepower and torque of 474 pounds per foot. The LS7 uses racing-derived cylinder heads, which allow for high airflow. There are also the 70cc combustion chambers and computer numerically controlled intake and exhaust outlets. They do away with airflow restrictions, further contributing to this naturally aspirated engine’s power. A high-flow intake manifold works in tandem with the cylinder heads. Acoustic foam and an acoustic shell on the intake manifold help reduce engine noises. The LS7 is excellent when it comes to oil consumption, courtesy of the dry-sump oiling system. This oil system brings about ample lubrication, more so in high RPM conditions.

LS3 vs. LS7 Specification

When comparing the two engines, one critical area to pay attention to is their respective specifications. LS3 and LS7 have several similarities, such as both being derivatives of the LS2 engine. They are updates of the LS2, having an almost similar engine block as their predecessor. They are aluminum builds, with some parts being steel and titanium. It makes them durable and light, crucial features for this car part. Both engines use the 58X ignition system, which comes in handy in ignition timing.

LS7 and LS3 differences include their respective displacements. The former has a 7-liter displacement, while the former has a 6.2-liter value. They share several features with the LS2, more so the design. Among the updates that make them different is the bore size. Both have larger bore sizes than the LS2. The LS3 and LS7 engine bore sizes are almost similar, with the LS7’s being some millimeters thicker.

Another area to look at is the LS3 vs. LS7 hp, where the LS7 is more powerful with 505 horsepower. LS3 has a value of 430 horsepower. An LS3 supercharger fitted during engine mods can boost its horsepower to impressive peaks.

Specs LS 7 Engine LS 3 Engine
Part Number: 19329246 19369326
Camshaft Duration 211° intake / 230° exhaust 204° intake / 211° exhaust
Rocker Arms EX Investment-cast, roller trunnion Investment-cast, roller trunnion
Maximum Recommended rpm 7000 6600
Cylinder Heads CNC ported LS7-style ports; 70-cc CNC combustion chambers Aluminum L92-style port; “as cast” with 68-cc chambers
Engine Type: LS-Series Small-Block V-8 LS-Series Gen-IV Small-Block V-8
Connecting Rods Forged titanium Powdered metal
Reluctor Wheel 58X 58X
Balanced Internal Internal
Recommended Fuel Premium pump Premium pump
Block Cast aluminum with six-bolt steel main bearing caps Cast aluminum with six-bolt, cross-bolted main caps
Rocker Arm Ratio: 1.8:1 (offset, intake only) 1.7:1
Camshaft Hydraulic roller Hydraulic roller
Pistons Hypereutectic aluminum Hypereutectic aluminum
Rocker Arms In Investment-cast, roller trunnion Investment-cast, roller trunnion
Displacement 427 (7.0L) 376 (6.2L)
Valve Size 2.200 titanium intake / 1.610 sodium-filled exhaust 2.165 intake / 1.590 exhaust
Compression Ratio: 11.0:1 10.7:1
Valve Lift 593 intake / .588 exhaust 551 intake / .522 exhaust
Crankshaft Forged steel Nodular iron
Bore x Stroke 4.125 x 4.000 (104.8 x 101.6mm) 4.065 x 3.622 (103.25 x 92 mm)

LS3 vs. LS7 Reliability

The next part of the debate is the LS3 vs. LS7 reliability question. Which of the two is the most reliable? Both engines come from General Motors, a company renowned for making quality parts. It means that the two-car parts are better than most when looking at their reliability. They are light in weight, courtesy of their aluminum build, which also contributes to their durability.

 While they are almost similar, the LS7 has an upper edge when you look at its power. Engine power is a crucial consideration when focusing on reliability. Here, the LS7 takes the top spot as it has a peak of 505 horsepower and 470 pounds per foot in torque.

LS3 vs. LS7 Performance

Like reliability, the performance also looks at the two LS engine’s power output. The LS3 has a displacement of 6.2 liters and 430 horsepower, and a torque of 424 pounds per foot. With modifications, the horsepower can reach 436 horsepower, with a possibility of going higher with a supercharger. On the flip side, the LS7, with a 7-liter displacement, has 505 horsepower.  With mods, it can go up to 570 horsepower.

LS3 vs. LS7 Engine Price

When picking a car part, you should pay attention to the price. While you may want to go for the cheapest component, you should focus on the price. The LS3 engine price is around $7000 to $13000, depending on your dealer.

On the flip side, the LS7 engine price ranges from $14000 to $17000. It is higher than the LS3, probably due to its impressive performance and specs. You can see that the price difference between the two engines is around $4000. If you want the best value, you can overlook the difference and go for the LS7. However, if on a fixed budget, go for the LS3.

A point to note is that you may find cheaper variants of the LS3 and LS7. There are iron types that are way more affordable, though you compromise on lightness and other aluminum attributes.

LS3 Engine Pros

LS engines have many pros, which you will notice in the LS3. A standout advantage is its power of 430 horsepower before any boosting. It is relatively robust, a reason it found prominence in muscle and power cars. Another pro of the LS3 is its aluminum build. Aluminum is strong and light; hence, it transfers these characteristics to the LS3 V8. Other parts are steel builds, which is a sturdy material, further improving the LS3’s durability factor.

This General Motors vehicle part has a wide bore. It translates to a displacement of 6.2 liters. A perk of the increased bore width is a faster response to throttle inputs and a rapid revving rate.  The LS3 is versatile due to its small stature, as it can fit into most vehicles.


A common problem with the LS engine types is piston ring faults. If not responded to, faulty piston rings can lead to high oil consumption or engine blow-by. The piston problem mostly comes about when you decide to mod the engine.  The compact size of the LS3 engines can make maintenance challenging. For example, if you want to replace the lifters, you have to pull out the entire engine for access.

LS7 Engine Pros

A noticeable LS7 engine pro is its high performance of 505 horsepower. This power output makes it suitable for power vehicles, like those in the sporting scene. The engine is light and durable due to its aluminum construction. As such, you do not have to worry about replacing it as it is very sturdy.

Its parts are easy to come by; thus, maintenance, mostly repairs, is a stress-free engagement. The 58X ignition system is critical for accurate ignition timing. The result is enhanced performance and good fuel economy.


An issue that you will encounter on most LS engines is with the oil system due to cavitation issues. The good thing is that you can replace the oil system with a preferred one to check the cavitation problem, which comes in the way of oil supply. LS3 engine swaps can be pretty expensive, especially when getting a compatible transmission system.

On the pros, you should note that there are ample aftermarket parts for the LS3 and LS7. Getting the components is easy and cheaper.

Frequently Asked Questions (FAQs)

Which Is Better, LS3 or LS7?

The LS7 is better if you want a high power output, where it gives you 505 horsepower. With improvements, you can achieve more power, around 570 hp. The LS3 is also great in power output, though, at 430 horsepower, it is lower than the LS7. If you want more power, the LS7 is a good option. For moderately high power discharge, go for the LS3.

What Is The Difference Between LS3 And LS7?

The LS3 and LS7 have several physical differences that can help you know which one you have under your vehicle’s hood. First of all, the LS7 has a larger exhaust port than that of the LS3. The LS7 tubes seem closer to the throttle body, whereas those of the LS3 are thicker and appear to be higher set from the throttle body.

The other variation of these two GM V8 engines is their displacement and output. LS3 has a 6.2-liter displacement and an HP of 430. LS7 is a 7-liter engine with a 505-horsepower value.

Which LS Engine Is The Best?

When looking at the best LS engine, you touch on the LS9 vs. LS7 debate. In this discussion, you realize the LS9 is the best, with a power discharge of over 600 HP. However, many people go for the LS3 as it is moderate and cheaper when opting for swaps.

Can You Put LS7 Heads On An LS3?

Yes, you can fit an LS7 on LS3 heads, and it will perfectly fit. The problem that you may encounter is that the valves may fail to clear, affecting their functionality.

Can LS7 Handle Boost?

Boost refers to the positive pressure from a supercharger or turbocharger that boosts the engine power. The LS7 can handle boost, but to a specific limit, with some motorheads suggesting up to 1000 horsepower. Past that, it may be dangerous due to heating. Some ways to boost LS7 are increasing the bore width, installing a turbocharger or supercharger, and bottom-end upgrades to the rotating assembly.

Final Words

The LS series from General Motors are excellent small-block engines, giving their best output. In this article, we tackle the LS3 vs. LS7 debate to understand each of them better. You can go through this piece to get a clearer picture of these LS builds and the areas they stand out. Pick a suitable engine for your desired driving experience.

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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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