The Chevrolet LS vs LT Engine Comparison. The Chevy LS is now one of the most infamous engines in practically every motorsport discipline. The LS has shown its flexibility in practically every application imaginable over decades of trial and suffering. It powered two generations of Corvettes and was utilized in a variety of other GM vehicles including the Camaro, Cadillac CTS-V, and Chevy Tahoe. From in 2006, the LS2 was used as the NASCAR Specification Engine in the Camping World Series East and West divisions. It is also a fan favorite in the hot rod, drifting, and endurance racing circles. The LS can do everything.
Nevertheless, the LS is now an outdated format. The original LS1, which started it all, was released in 1997 with the C5 Corvette. A lot has changed in engine technology in the 25 years since the LS was released. Here is where the LT1 engine comes in. The Chevy LT1 engine has a long history and three variations. We’ll be discussing the Gen V Small Block in the context of this essay and what I just mentioned. By this point, the LT1 had taken over from the LS and introduced a slew of controversial new features into the mix.
We’ll go through everything in further detail below, and there’s a lot to discuss. Despite doing similar work, the LS and LT engines share virtually little. To keep this essay from becoming 100 pages long, we’ll compare the LS3 and Gen V LT1, as they’re a good fit.
The History of the Chevrolet LS3
Chevy had already firmly established their upgraded LS small-block formula by the time the LS3 arrived in 2008. The contemporary LS layout was basically a blank sheet design, but it borrowed learned aspects from the 1954 Gen I and Gen II Chevy small blocks. Despite its four-decade delay, the LS family shares a few parts with earlier Gen I and Gen II small-blocks, such as connecting rod bearings and valve lifters.
Chevy had already released four variants of the LS before the LS3, including the LS1, LS6, LS2, and LS7. All of the LS variations are very similar in terms of overall construction. The 1997-released LS1 marked the beginning of a new generation of Chevy small-block design, with notable improvements over the Gen I and Gen II small-blocks such as alluminum block construction (retaining cast iron blocks for trucks and SUVs), a higher flowing cylinder head, a stronger rotating assembly, larger camshafts, and electronic fuel injection, among other things. The LS3 retained and improved on all of the advantages of the original small-block design.
The Chevy LS3 is a Gen IV LS engine that was first featured in the 2008 Corvette. The LS design of Generation III and Generation IV is generally similar, but there are a few important variations between the LS1 and LS3. Displacement is one of the most noticeable changes.
The displacement of the LS1 is 5.7 liters, whereas the displacement of the LS3 is 6.2 liters. This immediately offers the LS3 a performance advantage. Also, on both the intake and exhaust sides, the LS3 has a substantially better flowing head than the LS1. The LS3 also has a new intake manifold with less turbulent intake runners, which increases airflow to the head.
Specs for the Chevy LS3 Engine
The LS3 engine is a really amazing engine in terms of both technology and performance. While older Chevy small-blocks are still popular in many automotive groups, the LS3’s refinement put it in a class of its own. Apart from its tremendous horsepower and torque output, the LS3 incorporates some noticeable strength and rigidity-enhancing characteristics.
The LS3 features a deep skirt design that extends over the crankshaft centerline, increasing stiffness and reducing engine vibration. LS3 engines are 6 bolt main engines, which means that the heads are secured to the cast aluminum block with 6 bolts per cylinder. This is an incredibly sturdy configuration that improves reliability in higher horsepower ranges. Furthermore, the LS3 block includes a structural oil pan, which improves chassis rigidity.
The rotating assembly of the LS3 is particularly sturdy thanks to a solid iron crankshaft and powdered metal connecting rods. They also use flat-top alluminum alloy pistons that are both exceptionally strong and lightweight. The use of lightweight pistons enhances overall throttle response and efficiency.
The LT1’s History
The Chevy LT1 engine, like the LS, has a long (and often complicated) history. The LT1 engine has gone through three revisions so far, with the first appearing in 1970. The first LT-1 (notice the hyphen) engine was a game changer for Chevrolet at the time. It had a displacement of 5.7 liters, an 11:1 compression ratio, and 370 horsepower.
The LT1 (no hyphen) was debuted in the 1992 Corvette, five years into the production lifespan of the Gen II small block. The Gen 2 LT1 preserved a few key features that had been established by the previous edition. The Gen II LT1, like the LT-1, has 5.7 liters of displacement and a four-bolt main block. They also have the same bore spacing, with 4.4-inch bore centers, which is a feature shared by every version of Chevy small block.
While they are identical in many aspects, the Gen II LT1 is undeniably superior to the LT-1. The Gen II uses a reverse-flow cooling system, which cools the cylinder heads before the block. As a result, cylinder temperatures are lower and compression is higher. The Gen II LT1 generates 300 horsepower and 330 pound-feet of torque.
Fast forward 18 years to 2014, the year of the debut of the Gen V LT1. A much changed in engine technology between the Gen II and Gen V LT1 engines throughout the 18-year period. This is immediately reflected in the design of the Gen V. In numerous aspects, the Gen V differs significantly from the Gen II. The Gen V, for example, has a displacement of 6.2 liters, a cast aluminum block, a six-bolt main block, and is direct-injected.
Engine Specs for the Gen V LT1
The Gen V LT1 is the result of what is possibly the most significant small-block Chevy redesign in history. The Gen V LT1 is a blank sheet design from Chevy that borrows legacy staples from prior generations, similar to previous generation leaps. A cam-in-block pushrod construction and 4.400-inch bore centers are two of the most prominent commonalities.
Other from those similarities, there are numerous significant differences/improvements between the LT1 and the Gen V small-block series. In reality, there are so many changes that we can only examine the most notable ones. The addition of PCV-integrated rocker covers, dual-equal cam phasing (variable valve timing), direct injection, and active fuel management are among the notable changes.
Chevrolet LS vs. LT – A Comparison
On the surface, it’s easy to see why the LS vs LT debate exists. In terms of raw stats, the LS3 and LT1 appear to be a relatively even duel. Both engines have 6.2 liters of displacement, aluminum heads and blocks, and identical bore and stroke. Having said that, the differences between Chevy’s Gen IV and Gen V small-block architecture are substantial.
The introduction of a handful of the high-tech features of the Gen V LT1 has been welcomed with skepticism at best and outright contempt at worst. Long-time LS enthusiasts, in particular, despise the introduction of direct injection and active fuel management. They have good arguments for this as well, which we’ll discuss later. Regardless, the LT1 is unquestionably the most technically proficient engine, with some undeniable advancements over the previous generation small block.
LS vs. LT – Block Design
The design of an engine’s block is one of the most significant factors to consider when it comes to power. Chevy’s small-block engines have long been noted for their ability to be tuned and significantly modified without causing too much internal commotion. Both the LS3 and LT1 have incredibly sturdy blocks that are built to take a lot of damage from the factory.
Aluminum cylinder blocks are standard on both the LS3 and LT1. Indeed, the LS and LT platforms have a common block design. While both can handle much more power than stock, the LT1 has a stronger block. A factory LS block is rated for 700 horsepower reliability, whereas the LT1 is rated for 900 horsepower reliability. This is due to the LT1’s innovative aluminum casting technology and the incorporation of gusseted water jackets, which boost cylinder wall strength.
The LT1 additionally has eight under-piston oil sprayers that spray cooling oil on the bottom of each piston and the cylinder wall. This is advantageous for a variety of reasons. The extra oil reduces not only friction but also the temperature inside the combustion chamber. As a result, compression is increased, power is increased, and efficiency is improved.
LS vs. LT – Fuel Injection
The installation of direct injection was one of the most major, and possibly most contentious, alterations made to the LT1. The Gen V small block generation is the first to include direct injection. The Gen IV LS3 has electronic port injection, which appears to be popular among small block aficionados. Carbon buildup on valves in direct injection engines is a prevalent problem, and the LT1 is no exception. Removing the heads to remove carbon buildup is a hassle that you’d prefer to avoid, which is why so many Chevrolet aficionados are averse to it. It also provides tuning challenges for individuals who are accustomed to modifying port-injected engines such as the LS.
Having said that, there are substantial advantages to direct injection as well. Direct injection sprays gasoline directly into the combustion chamber, while the intake valves only provide air. Direct injection is a more exact technique of fuel injection because the spray pattern of the fuel infusion may be better regulated. As a result, the inside of the cylinder burns more thoroughly. This results in higher horsepower and a 15% improvement in fuel efficiency.
Direct injection also necessitates a massive amount of fuel pressure to function. As a result, the LT1 requires a high-pressure fuel pump in addition to the gasoline tank-mounted one. The high-pressure fuel pump of the Gen V is located in the valley between the cylinder heads. This helps reduce noise while simultaneously maintaining the engine’s size to a minimum.
LS vs. LT Heads and Valvetrain
Chevy’s small-block cylinder heads have traditionally been regarded as excellent. The LS3’s racing-derived cylinder head design had unusually high flow figures, which aided its overall performance greatly. To work in tandem with its direct injection technology, the LT1 required a new cylinder head design. As a result, the LT1 has a completely redesigned cylinder head casting. The revised design is intended to support maximum airflow at high rpms while preserving decent torque characteristics at low rpms.
Looking at the changes between the LS3 and LT1 cylinder heads, you’ll notice several obvious differences. The LS3 and LT1 heads’ intake and exhaust valves have been reversed, with the LT’s exhaust valves to the right of the intake valves. For the LS3, the opposite is true. This improved flow slightly on the LT1 and moved the spark plugs to a better location for direct injection.
To compensate for its dished pistons, the Gen V LT1 has a smaller 59.02cc combustion chamber. Each of these characteristics work together to raise the LT1’s compression ratio to 11.5:1. The intake ports on the Gen V were likewise altered to be straight and rectangular. Valve angles were also altered between Generation IV and Generation V.
The LT1 also has a much larger diameter camshaft with a new rear cam bearing. The bigger lobe provides smoother valve action than a smaller cam. It also features an extra “trilobe” that is in charge of running the additional high-pressure fuel pump.
Chevrolet LS vs. LT – VVT (Variable Valve Timing)
While variable valve timing isn’t a new concept for Chevrolet or many other manufacturers, the VVT system found in the Gen V LT1 is the company’s most advanced system to date. Unlike prior generation LS engines, which had binary variable valve timing, the LT1 had continuous variable valve timing. In most cases, variable valve timing is activated at a specific rpm to improve high-rpm performance. That is how Honda’s VTEC and prior generation LS VVT systems work. The LT1, on the other hand, has VVT turned on all the time.
The LT1 accomplishes this through the use of a sophisticated cam phaser. This changes the camshaft angle, advancing or retarding time for any driving situation. At low rpms or at idling, the cam is fully advanced, resulting in a buttery smooth idle. The phaser can retard timing at high rpms to generate maximum airflow and high-rpm power. The continuous system’s beauty is that the phaser can adapt on the fly, always altering the cam position to its best position.
This system produces an incredibly flat torque curve, high specific output without losing engine response, improved overall drivability, and an insanely smooth idle.
Chevrolet LS vs. LT – Dynamic/Active Fuel Management
Another technology found on both the LS and LT1 is active fuel management. The mechanism on the LT1 is, however, more sophisticated and less obtrusive. The system has gone by many different names over the years, but on Gen IV engines it was known as “Active Fuel Management,” and on Gen V engines it is now known as “Dynamic Fuel Management.” To increase total fuel economy, both systems routinely shut down cylinders based on driving circumstances.
Active fuel management was a binary system that was either on or off on LS engines. The active system on LS engines can only run on 4 or 8 cylinders. The small block community rejected this approach since it was obtrusive and far from flawless. The switch was startling since the system would shut down and restart four cylinders at a time.
Many of the hitches in the previous “Active” system have been ironed out with the LT1’s new dynamic fuel management system. The dynamic system, as opposed to the active system, may shut down and reactivate cylinders individually, making the performance shift less dramatic and obvious. The dynamic system reads sensor data 80 times per second to calculate how many cylinders should be running at any given time. It is also more dependable than the previous system because Chevrolet addressed the oil feed difficulties that created problems in the past.
Conclusion: Chevrolet LS vs. LT
The LT1 is a completely redesigned engine, hence there are several differences between it and the LS. Chevy’s Gen V small block is the company’s most advanced design to date. It truly shows when you consider all of its new high-tech features. While the majority of the LT1’s advanced technology is an advantage over the LS3, some believe that it simply adds more things to go wrong.
Generally, the LS platform is well-known and appreciated for its ease of use. Its lack of fancy gadgets is what draws so many fans to it for such a wide range of applications. While Gen III and Gen IV Chevrolet engines are more modern than Gen I and II small blocks, they have many of the same characteristics. Because LS engines have been around for so long, they have a lot of aftermarket support in addition to being straightforward to work on. The Gen V LT1 does not yet have that level of modifiability.
However, the LT1 is a more advanced engine with numerous performance advantages. At its most basic, it has a stronger block and better flowing cylinder heads than the LS3. Constant variable valve timing is a difficult feature to dislike because it enhances performance significantly at all rpms. Those modern features, however, come at a far higher cost than what you’d pay for an LS.
