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Ls3 Vs Ls7

Ls3 Vs Ls7: Which Engine Is More Powerful?

Many experts often say the engine is the heart of a car. That’s right, and the engine is the part that helps convert fuel into the driving force that allows the car to move. Without the engine, the car would be useless.

Conversely, the better the machine, the better the car.

Today, let’s learn about two one, LS3 vs LS7. They belong to the LS family – the high-quality and prestigious engine line of General Motors.

Overview Of The LS Engine

LS is the common name for the small-block V8 gen III and gen IV gasoline engines of General Motors. LS was born to replace the traditional small block engines (Gen I and Gen II).

LS1 is the first one of the LS series launched in 1997. Up to now, the LS line includes models: LS1, LS6 of gen III and LS2, LS3, LS7, LS9 supercharged, and LSA supercharged of gen IV. Due to the same line, most Gen III and Gen IV parts are interchangeable.

Standard features of the more advanced LS compared to previous generation engines include:

  • Aluminum blocks for cars and cast iron blocks for most trucks
  • 6-bolts, cross-bolted main bearing caps
  • Bore centers are 4.40 inches wide.
  • Lifter bores 0.842 inches.
  • Increased airflows thanks to long-runner intake manifolds.
  • Improved ignition system: It is to replace the distributor with valve cover mounted ignition coils. As a result, the ECU can control the fuel combustion time through the camshaft and crankshaft position sensor (CKP sensor).
  • Therefore, if these engines vibrate strongly or have difficulty accelerating, you should have the CKP sensor checked and repaired .

However, there are also differences between the LS gen III and IV engines that bring their advantages. Notable differences are:

  • Position of crankshaft position sensor (CKP): Gen IV blocks have CKP in front of the timing cover while Gen III’s CKP is in the top-rear place.
  • Most Generation IV LS feature GM’s Active Fuel Management, which shuts down half of the cylinders under light loads and helps save fuel.

Standard Features Between LS3 Vs LS7

In 2005, automaker GM released the LS2 product, the fourth generation engine of Small blocks V8. After that, GM upgraded the LS2 and introduced the LS7 (2006) and Ls3 (2008) engines to improve performance and fuel economy.

# Source

Both the LS3 and LS7 engines belong to the IV generation LS family of engines. They are all improved models of the LS2 engine, so most of the exterior design is inherited from the original one. However, both machines have more expansive bore centers than the LS2 that helps to vary cylinder volume.

# Material of the engine

Like the LS’ other Gen IV, the LS3 and LS7 are primarily aluminum with a few titanium and steel components. Thanks to the construction of these metals, the LS3 and LS7 engines have solid, durable, and bright construction.

# Ignition system

As mentioned, both the LS3 and LS7 use a 58X combustion system controlled by the ECU via a crankshaft position sensor. This system operates to burn fuel in precise time, helping to increase capacity and save energy.

At the same time, GM also integrated Active Fuel Management into the Ls3 and Ls7 to help save fuel when the vehicle is not carrying heavy loads.

Difference Between Ls3 And Ls7

difference between ls3 and ls7

Despite the exact origin, design, and some technical characteristics, the Ls3 and LS7 have many suitable differences for different uses.

# Specifications

The first difference is the displacement parameter. If the LS7 has a displacement of 7.0L (427 cu-in), the LS3 has a lower displacement of 6.2L (376 cu-in). Furthermore, although the bore centers of LS7 are both larger than LS3, they are similar in size.

# Wattage

Another thing to consider when comparing 2 motors is the power they can produce. The energy from the engine will determine the speed and acceleration time of the vehicle. And the specification of the motor is what determines its output power, which is usually expressed in horsepower (HP).

The cylinder capacity of the LS3 engine is 6.2L, and the power generated is 430 HP. However, if you change a few details of the LS3, the energy output can reach 436 HP and be higher.

Meanwhile, the LS7 engine belongs to a large capacity engine with a power of 505 HP and a cylinder capacity of 7.0L. In addition, the LS7’s intelligent lubrication system also helps reduce friction and increase engine RPM.

# Reliability and durability

Since General Motors both use quality parts to manufacture the LS3 and LS7 engines, the reputation of the two is the same. They are lighter than other iron and steel engines thanks to their aluminum construction while maintaining their strength and durability.

# Price

Two engines with two different capacities and different specifications will certainly have different prices. If the LS3 engine only costs from $ 7000 – $ 13,000, the LS7 engine with better capacity and specifications costs about $ 14,000 – $ 17,000.

If you are looking for a version with sound engineering, then you can choose the LS7. However, if you are looking for an engine line that fits your budget, the LS3 is also an optimal choice.


We have just reviewed the overview and details of 2 engines LS3 and LS7. Because they all belong to GM’s LS Gen IV Small blocks V8 line, you can be assured of quality and prestige.

However, due to the difference in specifications, the two have different capacities and prices. So, consider choosing the right one for your needs and pocket.

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