LS3 vs. LS7 vs. LS9: Which One Is The Best?

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The LS3, LS7, and LS9 are among the most popular engine choices in the market. They all have distinctive features, advantages, and disadvantages, but how do you tell which one suits you best?

This article will compare LS3, LS7, and LS9, and pick the best one out of the three.

Let’s kick off things with a comparison table below.

LS3 vs. LS7 vs. LS9: Comparison Table

LS3LS7LS9
Cylinder Heads68-cc combustion chambers70-cc combustion chambers69.8-cc combustion chambers
BlockCast Aluminum with 6-bolt cross-bolted main capsCast Aluminum with steel 6-bolt steel main bearing caps319-T7 Aluminum
MaterialAluminumAluminum319-T7 Aluminum
RPM660070006600
Horsepower430 hp505 hp638 hp
Torque420-428 ft/lbs470-481 ft/lbs470-481 ft/lbs
ReliabilityYesYesYes
Longevity100,000 miles250,000 miles100,000 miles
Engine TypeGen IV Small-Block V-8LS-Series Small-Block V8Gen IV V8 Small Block
Firing order1-8-7-2-6-5-4-31-8-7-2-6-5-4-31-8-7-2-6-5-4-3
Weight466 lbs454 lbs531 lbs
Fuel efficiency14-17 MPG30-31 MPG22 MPG
Price$7,000 – $13,000$14,000 – $17,000$21,403 – $26,403

LS3 vs. LS7 vs. LS9: Detailed Comparison

Material (Cylinder heads, blocks)

All three engines are made from Aluminum and Steel components. That makes these engines slightly lighter than most others in the market. The Cylinder heads are all (68-70) cc combustion chambers.

All the engines are durable, and you won’t see a part frequently break or wear out.

Performance (Torque, Horsepower, RPM)

An engine’s torque, Revolutions per Minute, and horsepower will be one of the critical determiners when buying a vehicle. They determine what type of work the engine will be capable of withstanding.

Among the three engines, the LS9 comes with the highest horsepower, 638 hp, while the LS3 and LS7 come in at 430hp and 505hp respectively. Well, that’s a solid reason to conclude that the LS9 gives the most reliable performance of the three.

The LS7 and LS9 give 470-481ft/lbs of torque, making them better choices over the LS3. When it comes to RPM (Revolutions Per Minute) the LS7 peaks at 7,000 RPM while both the LS3 and LS9 give a maximum of 6,600 RPM. The LS7 seems to perform work faster. If you need some speed, the LS7 should be your choice.

Reliability & Longevity

Which of the engines is most reliable? Which one can you trust for that consistent output over a long period? Well, let’s find out.

The LS3 has slightly inferior characteristics in power, which is a vital aspect to consider regarding cars’ performance. The LS9 is the most reliable of the three when it comes to power. However, the LS7 goes the furthest when it comes to longevity.

Both the LS3 and LS9 have a lifetime of 100,000 miles, while the LS7 has 250,000 miles. Yeah, you know which engine will be lasting longer. 

Ignition 

The LS3, LS7, and LS9 use an ECU-controlled 58X controlled system via the crankshaft position sensor. The system helps to save energy, increase output capacity, and burn fuel with precise timing. Moreover, GM integrated an Active Fuel Management system for effective fuel management, especially when the car is not dealing with heavy loads.

Engine Type

The LS3 is a 6162cc (376.0 ci) put right behind the crate engine, with a maximum output of 450hp @ 5900 RPM. It succeeds the LS2 6.0L V8 but comes with a more robust casting and slightly larger bores.

The LS7 is a high-power crate engine, which peaks at 570hp and 540 ft-lb of torque. It is among the strongest naturally aspirated engines in the world. 

The LS9 is also a high-performance engine from General Motors. It is a Small Block V8 engine popular for its high peak performance. The LS9 gives a fantastic 638 hp at 6600 RPM.

Firing Order

All LS engines have the same firing orders. The firing order is essential in maintaining a sequential cylinder action and, therefore, preventing vibration of your car. The LS3, LS7, and LS9 all have the 1-8-7-2-6-5-4-3 firing order. It is the order in which the cylinders perform combustion.

Read more: Bilstein 5100 Vs. 5160 Vs. 6112: What Do You Drive?

Weight

The LS7 is the lightest of the three, averaging at 454 pounds. The LS3 comes with 466 lbs, while the LS9 is the heaviest, 531 lbs. However, these engines are lighter than most, thanks to their aluminum compound construction. 

Fuel Efficiency

If you wish to save on fuel, it’s advisable to stay away from the LS7. It consumes a massive average of 30-31 miles per gallon, which is way higher than the other two. The LS3 has the best fuel efficiency, hitting 14-17 MPG on highways. The LS9 averages at 22 MPG, which is slightly more manageable than the LS7.

Even when the LS7’s fuel consumption may be higher than that of the LS9; the latter is more powerful due to its built-in supercharging property.

Price

No matter how impressive an engine’s features are, it won’t be helpful if you can’t afford it. So, you have to consider the financial aspect of the engines.

These three engines have different capacities, specifications, and outputs, automatically translating to different prices. As you’d guess, the newer, more advanced LS9 is more expensive than the other two engines. It costs around $21,403 – $26,403. The LS7 is relatively cheaper, while the LS3 is the cheapest engine at $7000 – $13000. 

LS3 vs. LS7 vs. LS9: Other Specifications

LS3LS7LS9
Displacement6.2L7L6.2L
CamshaftHydraulic RollerHydraulic RollerHydraulic Roller
CrankshaftNodular IronForged SteelForged aluminum alloy
Compression10.7:111.0:19.1:1
Bore/StrokeBore: 4.065 inStroke: 3.622 inBore: 4.125 inStroke: 4.000 inBore: 4.065 in.Stroke: 3.622 in
Exhaust runner volume87cc86cc89cc
Fuel injector flow42 lbs/hr41.74 lbs/hr59 lbs/hr
Rocker Arm Ratio1.72:11.81.7:1.
Valve Size (Diameter)1.590 in.1.61 in.1.590 in.

Which Vehicles Have These Engines?

LS3LS7LS9
+ Camaro Chevrolet Corvette
+ Corvette Grand Sport
+ Pontiac G8 GXP
+ Camaro Z28
+ Chevrolet Corvette Z06
+ Equus Bass 770
+ Chevrolet Corvette ZR1
+ HSV GTSR W1

FAQs

1. How much does it cost to do an LS3 swap?

Swapping your LS3 will cost you around $1500 to $2000. The value might vary due to fluctuations in hourly labor prices in various places. That price will cater for a swap with a standard truck engine, your existing cross-member, rear axle, and factory exhaust manifolds.

If you need to swap with fabricated oil pans, aftermarket cross-members and rear suspension overhauls will cost you more.

2. Can LS engines swap with each other?

Yes! LS engine swaps are made to increase vehicles’ quality, power, and productivity. They are versatile in their ability to ‘accept’ swaps, and it wouldn’t be a problem swapping an LS Engine with another one. However, please swap your LS engine with another one with a higher output – Don’t do it only for the cosmetics.

Sum Up

Which LS engine should you go for? Well, it depends on what you need from it. All engines are masterpieces from General Motors and have their share of strengths. The LS3 is the cheapest engine of the three, while the LS9 is good for power/output. However, the LS7 is the most preferred due to its longevity and lower price compared to the LS9.

Read more: Ford 5.4L vs 4.6L vs 5.0L Engine: Which Is The Best?

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