For any General Motors performance enthusiast, the question of LS versus LT is an old debate.
Both are powerful V8 engine families, and both are from General Motors. Choosing between them requires careful thought about your project, your budget, and what technology you need.
This guide compares the LS and LT engines to help you decide which is best for you. We’ll look at their history, their technical differences, what aftermarket support they have, and what kind of applications each is best for.
Ultimately, the “best” engine will depend on what you need and what your priorities are.
A Brief History of the LS and LT Engine Families
Both the LS and LT engine families have powered a wide range of GM vehicles. Here’s a little background on each.
The Legacy of the LS Engine
The LS engine first appeared in 1997 and quickly became known for its versatility, affordability, and the robust aftermarket support it enjoyed. From Corvettes to trucks, the LS engine family was used in millions of full-size pickups and vans.
Because it was produced for so long and used in so many vehicles, the LS engine remains readily available today.
The Modern LT Engine
As a replacement for the LS engine, the LT engine represents a significant advance in GM’s V8 engine technology. Introduced in 2014, the LT engine is a more modern design that showcases improved performance and efficiency.
Although the LT engine is newer, it’s becoming increasingly available on the market.
Technical Differences: LS vs. LT
While both the LS and LT engine families are based on the same cam-in-block pushrod V8 design, the LT engines incorporate some key improvements.
Key Improvements in the LT Engine
The LT engines have a tougher block, better oiling system, and bigger head bolts, making them sturdier than the LS. They also use direct fuel injection, which improves efficiency and power. Better flow through the heads and variable valve timing (VVT) also contribute to better performance.
LT engines often use aluminum blocks, while LS engines sometimes use iron blocks. The aluminum helps keep the engine lighter.
The advanced variable valve timing (VVT) in LT engines allows for a wider range of camshaft angle adjustments. The LT VVT can adjust the camshaft up to 62 degrees, while the LS can only adjust it up to 20 degrees.
LS Engine Simplicity and Reliability
LS engines generally don’t have some of the advanced features found in LT engines, such as cylinder deactivation (active fuel management) and direct injection. While these features can improve fuel economy, they also add complexity.
The relative simplicity of the LS engine can translate to greater reliability and make it easier to modify. The cam-in-block pushrod V8 design is a core element of both engine families.
Performance: Power and Fuel Economy
LT engines tend to crank out more horsepower and torque than comparable LS engines. For example, the 6.2L LT1 generates around 455 horsepower. The older 5.7L LS1 only made about 350 horsepower.
The direct injection system on LT engines is one of the reasons they’re more fuel-efficient.
But to really see the potential of the LT platform, look at the LT6 in the C8 Corvette Z06. It’s a high-revving, naturally aspirated V8 that proves just how far GM has come with the LT series.
Aftermarket Support and Availability
When it comes to modifying your engine or swapping it into a different vehicle, the availability of parts and expertise is critical.
LS Engine: The King of Aftermarket
The LS engine wins hands-down in this category. Because it was around longer and is so popular, the LS has far greater aftermarket support. You can find LS engines in a dizzying array of configurations, and the number of upgrades and performance parts available is almost limitless.
LT Engine: Catching Up
The LT engine aftermarket is growing, but it still has a ways to go to catch up with the LS. As LT engines become more common, expect aftermarket support to expand.
Institutional Knowledge and Swap Experience
If you’re planning an engine swap, keep in mind that there’s a lot more accumulated knowledge and experience out there for LS engines. That can be a real advantage if you’re tackling a project build.
Frequently Asked Questions
Is a 5.3 an LS or LT?
This is where it gets tricky! The 5.3L engine was initially part of the LS family, specifically the LM7, L33, and LMG variants. However, later versions of the 5.3L, like the L83, transitioned to the LT family. So, it depends on the specific year and application of the 5.3L engine. Always check the engine code to be sure!
What’s the difference with LT and LS?
The core difference lies in their architecture and technology. LS engines are known for their simple, reliable pushrod design. LT engines, on the other hand, incorporate more advanced features like direct injection, Active Fuel Management (AFM), and Variable Valve Timing (VVT) for improved efficiency and power. Think of LS as the classic, proven design, and LT as the modern, technologically advanced evolution.
Is a 6.2 an LS or LT?
Similar to the 5.3L, the 6.2L engine has both LS and LT variants. The LS3 and L99 are LS-based 6.2L engines. Later, the LT1 and LT4 became the LT family versions. Again, engine codes are your friend here! Knowing the specific code is the only way to be 100% certain whether you’re dealing with an LS or LT 6.2L.
Closing Thoughts
Choosing between an LS and an LT engine really comes down to what you want to achieve. Think about your project’s goals and the kind of performance you’re after.
If affordability and lots of customization options are key, the LS engine might be the better bet. But if you’re looking for modern tech, more power, and better efficiency, the LT engine is a strong contender.
Don’t forget to factor in how easy it is to find the engine you want, the availability of aftermarket parts, and, of course, your budget. Keep in mind that modifying either engine family can be tricky and costly, so do your homework.
Knowing the specific tech differences between LS and LT engines is crucial for a successful swap, and the best choice ultimately depends on your individual needs and priorities.