LS vs LT Engine: Which Swap is Better? HP, Specs & Fitment Differences
Difference Between LT and LS Engines
It’s common, though incorrect, that many people tend to lump all GM V8 engines built after 1997 into the “LS” engine descriptor, but this is doing GM’s later LT engines a huge disservice. While the more modern and higher-tech LT engine variants are indeed more expensive and a bit harder to swap in some cases, they shouldn’t be ignored if you’re looking for something interesting under the hood and have the means to make it happen. Seeing an LS3 swapped first gen Camaro is quite common these days at the local cruise night, but spotting an LT4 with factory supercharger from a sixth gen ZL1 Camaro in the same first gen will no doubt have people stopping for a second look.
GM’s LS series of engines was introduced in 1997 in the new C5 Corvette as the Gen III small block Chevy, replacing the Gen II small block. The LS nomenclature comes from the original engine’s “LS1” regular production option (RPO) code. These Gen III, and later Gen IV (’05-’20) LS engines featured aluminum and iron block versions, all with aluminum cylinder heads, a cam-in-block traditional overhead valve valvetrain, and direct port fuel injection. The Gen IV engines offered larger displacements, improved internals, and optional variable valve timing (VVT). Their aftermarket support is extremely robust for LS swap needs.
Debuting in 2014, the Chevy LT engines (technically a Gen V small block) took the LS platform to the next level. Updates included better cylinder heads atop 6.2L displacements in performance applications (other displacements can be found in trucks and SUVs), the continuation of VVT and active fuel management (AFM) with the big news being the move to gas direct injection (GDI). Direct injection (GDI) explained in a nutshell: GDI moves the fuel injectors from before the intake valve to after, right into the combustion chamber, for better efficiency and performance. However, GDI (most simply say “DI”) uses a high pressure fuel system, like a diesel engine, with pressures upwards of 2,000 psi. A revised intake bolt pattern also appeared with the LT engines as well, preventing LS intake manifolds from being compatible without using adapter plates.
LS vs LT Engine Specs & HP
We’ve only touched on the most basic differences between LS and LT engines above. So, let’s dive deeper into each engine family, including their performance numbers, horsepower potential, and tuning abilities. We’ll also discuss the most important factor, which being availability to the average enthusiast via salvage yard finds, newly built crate engines, and more. We’ll also discuss the different LT engine vs LS engine variants GM offered and in what platform they were available in standard or as an optional engine for a specific trim level or package. While we’ll compare LS vs LT engine horsepower, we’re speaking only of factory rated horsepower here. Obviously, there’s more on the table with aftermarket performance parts, often allowing the LS to surpass the LT’s higher factory ratings with just some bolt on parts.
LS vs LT Performance Comparison
The LS series of engines has a lot of power potential with huge aftermarket support. Simple upgrades often will net north of 400 hp on even the smaller displacements. That said, we’re going to focus on factory performance numbers here. Sort of a “buy it and install it in your project” aspect. No big lumpy cam, no ported heads, no aftermarket intake. Just what GM rated it at the factory. The Gen IV LS is where GM really started making steam with the LS. Engines like the LS3 and LSA are highly sought after. The LS7 is no slouch at 505 horsepower, though the factory supercharged LSA and LS9 pump out between 556 and 638 horsepower depending on application and year.
Moving to the Gen V LT-series we start to see some serious factory horsepower numbers coming out of the General’s engine plants. The base LT1 (Camaro SS, GM trucks, and base Corvette) puts out 460 horsepower, which is nothing to sneeze at. Meanwhile, the supercharged LT4 found in the Camaro ZL1, Z06 Corvette, and CTS-V Caddy and the LT5 found exclusively in the Corvette ZR1 pump out 650 and 755 horsepower, respectively. So, the LT engine family certainly can show up and show off with its larger horsepower numbers vs its LS cousins, which is great if you just want to buy an engine and drop it down on the mounts. However, the performance potential of the LS cannot be denied with the vast aftermarket support that can provide the same, if not greater, performance numbers if you’re willing to crack your 5.3 LS open and get your hands dirty installing some 5.3 performance parts.
Availability And Tuning
It’s common knowledge that the Gen III LS, and to some extent the Gen IV LS, are readily available in salvage yards across the country. Yes, some specific models may be a little tougher to find than others or cost you a bit more to drag home. However, they are indeed out there and easy to find. These LS engines, as we’ve mentioned previously, have a large and supportive aftermarket (especially the 5.3 LS engine and 6.0 LS engine) of LS swap bits to fit these engines in not only just about any GM model ever produced, but non-GM rides like Foxbody Mustangs, Porsches, and more. One look at our LS Engine Swap Compatibility Chart will attest to their ease of fitment. Their factory EFI is also easily tuned by any competent dyno shop tuner or take the DIY route with an aftermarket EFI system.
The Gen V LT engine, on the other hand, is a bit of a different animal. Being a newer engine they are less likely to be found in your local salvage yard and when you do find one, they’re going to take more of your engine budget to bring it home with you. The high pressure fuel system with direct injection also complicates things for the home DIY builder. Tuning is a bit more difficult with needing to find a tuner familiar with the LT engine family and a specific LT swap harness. The LT engines are gaining in popularity though. The biggest issue with LT swaps right now is the differences between the LS engine vs LT engine blocks and heads, preventing most LS swap parts like mounts or adapter plates from working. Even the LT1 exhaust manifold bolt pattern is different. This isn’t a big deal if you’re starting with an LT, but if you’re currently running an LS swap in your ride and looking to upgrade to the LT, well then you have some research to do first on GM LS vs LT engine difference when it comes to swaps.
Common LS and LT Engine Variants
LS Engine Variants
Gen III LS Engines (1997-2007)
- LS1 (305-350 HP) – First LS engine; this 5.7L was found in C5 Corvette, Camaro, Firebird, and GTO
- LS6 (385-405 HP) – High-performance version of the 5.7L LS1; used in C5 Z06 and CTS-V
Gen IV LS Engines (2005-2020)
- LS2 (400 HP) – Larger 6.0L version of LS1; found in C6 Corvette, GTO, and Trailblazer SS
- LS3 (430-436 HP) – 6.2L engine with rectangular port heads; used in C6 Corvette, Camaro SS
- LS7 (505 HP) – 7.0L high-revving engine; exclusive to C6 Z06
- LS9 (638 HP, Supercharged) – 6.2L supercharged; found in C6 ZR1
- LSA (556 HP, Supercharged) – 6.2L supercharged; used in CTS-V and Camaro ZL1
Truck/SUV LS Engines (1999-2020)
- LR4/LY2/L20 (255-302 HP) – 4.8L iron-block; used in trucks and SUVs
- LM7 (270-295 HP) – 5.3L iron-block; common in trucks and SUVs
- LQ4/LQ9 (300-345 HP) – 6.0L iron-block; found in heavy-duty trucks and SUVs
- LY6/L76 (350-366 HP) – 6.0L truck engines with VVT and improved heads
- L92 (403 HP) – 6.2L truck engine; basis for the LS3
Gen V LT Engine Variants
- LT1 (460 HP) – 6.2L used in C7 Corvette, Camaro SS, trucks/SUVs
- LT4 (650 HP) – Supercharged 6.2L found in C7 Z06, CTS-V, Camaro ZL1
- LT5 (755 HP) – Supercharged 6.2L; C7 ZR1 exclusive
- L8T (401 HP) – 6.6L iron block/aluminum head for heavy duty trucks
- EcoTec3 L82/L83/L84 (355 HP) – 5.3L Truck/SUV version
- EcoTec3 L86/L87 (420+ HP) – 6.2L truck/SUV versions of LT1 with unique cams and intake
Is LT1 or LS1 better?
The Gen III/Gen IV LS engines and the Gen V LT engines are both popular swap options these days. While the LT engine offers the latest technology and more horsepower from the factory, there is no denying that the LS engine family is the current LS swap champion for a reason (even the 4.8 LS engine is a viable choice for budget builds. From the lower cost of entry, simpler architecture, and vast aftermarket swap support, the LS1 often beats the LT1’s direct injection, VVT, and other OEM features, even if the LT is more efficient due to improved cylinder heads and other factors. So, comparing the LT1 engine vs LS1, many will prefer the LS1. However, this isn’t just an LT1 vs LS1 argument, as there are many options in both LS and LT engines for your build.
Final Verdict: LS for Simplicity and the LT for Advanced Technology
- Choose an LS engine if you want a more affordable, easy-to-modify, and widely available platform. LS swaps are common, and the aftermarket support is massive. Something like an LS swap throttle cable is much less expensive than the LT’s drive by wire setup that requires swapping throttle bodies.
- Choose an LT engine if you want the latest GM technology with better efficiency, power, and reliability. However, swaps are more challenging due to direct injection and electronic complexity.
To summarize, the LS remains the best choice for budget builds, while the LT engine is great for those that want the latest and greatest in GM small blocks and are willing to work through the complexities of the Gen V LT platform.
Is the LT Engine Swap Worth It? Pros & Cons
The LT engine, even with its drive by wire throttle body, direct injection, and high pressure fuel system, is desired by many that want the best of the best innovative technology and performance in their GM small block swap. These are often high end builds that feature custom chassis, suspension, and big brakes along with fully fabricated interiors as well. If you’re willing to work through the LT-specific technology nuances (or pay the going shop labor rate for a shop to handle it) the LT is indeed a wise choice that will net you more performance, efficiency, and reliability, while providing that stop ’em in their tracks ability at the local cruise in. See the chart below for more pros and cons to discuss.
Final Verdict: Is an LT Swap Worth It?
If you’re looking for the hottest GM small block engine offerings to power your ride, then the LT V8 may just be your huckleberry. Provided, of course, you are willing and able to tackle the challenging LT bits like wiring, fuel system, tuning, and of course a smaller selection of swap components available. Significant performance gains are guaranteed with an LT swap, but you’ll have to deal with the complexities of the swap and other issues to succeed. This is why the LS swap is still the primary swap choice for many, as it is cheaper, easier to swap, and has extensive performance and swap product support. To review, you can often get an LS installed and upgrade its performance to LT levels for less than the total cost of an LT swap, including adding a sweet 5.3 LS engine dress up kit to keep ’em guessing!
The LS Engine Swap | A Trusted Classic
It’s easy to see why the venerable LS swap is here to stay. For many swap applications it is simply a matter of mount adapters and an LS transmission adapter to attach your existing transmission Short of wanting to build something with an LT for bragging rights, the LS, all the way back to the original 5.7 LS engine, is still going to be the go-to swap of choice for GM engine enthusiasts. It’s wide availability, low cost of entry, general cam-in-block overhead valve simplicity, and enormous aftermarket performance parts (like the popular LS swap turbo kit) and swap parts support make the LS swap practically a no-brainer for all but perhaps the diehard Ford or Mopar enthusiast. It certainly doesn’t help that the LS engine’s robust architecture allows for some serious power potential that rivals the LT engine’s factory ratings and often exceeds it with a stock bottom end build! It can literally fit in just about anything and our LS mockup block will help your LS swap go that much more smoothly in those “rogue” applications.
Why the LS Swap is Still the Best Choice
- Lower Cost LS engines are widely available and more budget-friendly than LT engines.
- Strong Aftermarket Support A vast selection of parts, upgrades, and swap kits makes modifications straightforward.
- Simpler Fuel & Ignition Systems Without the complexity of direct injection, tuning and maintenance are easier.
- Proven Performance Decades of success in high-horsepower builds demonstrate the LS engine’s reliability.
- Easier Swaps Well-documented installations and plug-and-play solutions simplify the process for various vehicles.
LT’s Advantages & Trade-offs
As we stated previously, the LT engine does provide for more efficient operation and higher horsepower levels (from the factory), but at the cost of added complexity and tuning. Not to mention the LT block is different enough that many LS swap parts we take for granted (engine mount adapters, accessory drives, etc.) simply will not work with the LT. This means higher swap costs and potentially additional fabrication expenses.
Final Verdict
For most builds, the LS engine remains the best all-around choice, offering a balance of power, simplicity, and cost-effectiveness. The LT engine is a viable option for those seeking the latest technology and willing to navigate the additional challenges.
LS vs LT Engine Swap FAQs
Which is better, LS or LT engine?
- LS: More affordable, simpler to swap, vast aftermarket support, and proven reliability.
- LT: Newer tech with direct injection, better efficiency, but more complex to swap.
Is the LS engine reliable?
- Yes, LS engines are known for their proven durability and reliability in performance applications, with many running for hundreds of thousands of miles.
What’s the difference between LT and LS engines?
- LS: Gen III & IV engines with port fuel injection and a simpler design.
- LT: Gen V engines with direct injection, better power efficiency, and more advanced technology.
Can an LT engine fit in an LS swap?
- Not easily. The LT engine requires more custom work due to its newer block design, electronics, and accessory mounting.
Which engine is cheaper, LS or LT?
- LS engines are generally cheaper, with lower initial costs and more affordable swap components compared to LT engines.
Which engine has more aftermarket support, LS or LT?
- LS: Much more aftermarket support due to its long history and widespread use in the performance scene.
- LT: Limited aftermarket support since it is newer and more complex.
What’s better for a swap, LS or LT?
- LS: Best for simplicity, cost, and ease of installation.
- LT: Better for those seeking modern technology, improved fuel economy, and more power potential if willing to tackle complexity.
Do LT engines have better fuel efficiency than LS?
- Yes, LT engines, with their direct injection, offer better fuel efficiency compared to LS engines.
Can I upgrade an LS engine to have direct injection?
- While it's possible with major modifications, it's easier and more efficient to start with an LT engine if direct injection is a priority.
Is an LS engine good for high horsepower builds?
- Yes, LS engines are widely used for high horsepower builds, with extensive aftermarket support to handle enormous power gains.
Which engine is easier to tune, LS or LT?
- LS: Easier to tune due to simpler fuel and ignition systems.
- LT: More complicated tuning due to direct injection and advanced control systems.
Technical content assistance provided by Jerad Flemming
