The Engine Comparison: LS1 vs. LS2

The Engine Comparison: LS1 vs. LS2. Since the LS2 replaced the LS1 in 2005, the LS1 vs LS2 controversy has raged among Corvette and GTO enthusiasts. Some argue that the newer LS2 motor is more capable, while others prefer the older but still strong LS1. We’ve previously discussed the LS1 vs LS3 and LS2 vs LS3 debates, but today we’ll look at the LS1 vs LS2 discussion.

There is no right or wrong answer, but we will examine everything between the LS1 and LS2 to see what the differences and similarities are. We’ll start with an overview of the LS engine’s history, technical specifications, and car applications before delving into the differences in engine design, reliability, performance, and top mods. Let’s get this party started.

The Engine Comparison LS1 vs. LS2

Engine History of the Gen III/Gen IV LS Series

GM/Chevy released their Gen III V8 small blocks, now known informally as the LS series, in 1997. The name comes from the first engine in the series, the LS1. The LS1 was a 5.7 L V8 engine that replaced the Gen II 5.7 L LT1 engine in the Corvette, Camaro, and Firebird. The LS1 was also utilised by GM affiliate Holden. Depending on the automobile, the LS1 produced 305-350 horsepower and 335-365 lb-ft of torque.

When GM/Chevy originally debuted the LS1, it was considered a huge deal in the automotive world. The LS1 was the first GM V8 to use an aluminium block, saving 50-80 pounds over the iron block LT1. It incorporated a lot of new technology from a new ECU while keeping the old school pushrod OHV valve train.

The LS1 was available in the United States from 1997 through 2004, when it was replaced by the bigger Gen IV 6.0 L LS2. The engine shared many similarities with the LS1, but it also included components from the LS6 engine, which was a high-performance variant of the LS1. The LS2 produced 400 horsepower and 400 pound-feet of torque, both of which were significant upgrades over the LS1.

The LS2 engine was produced by GM/Chevy from 2005 to 2009, after which it was replaced by the LS3 and LS7 engines. Many LS1 and LS2 Corvettes, Camaros, Firebirds, and GTOs are still on the road today, and many LS1 and LS2 engines have been used in various “LS swaps.”

While stock, the LS1 and LS2 produce 300-400 horsepower and torque, customised versions have exceeded 1,000 horsepower. The LS1 vs LS2 debate will never die because both engines are more than adequate.

Technical Engine Specifications for Gen III/Gen IV LS

The Engine Comparison: LS1 vs. LS2

Car Applications for LS1 and LS2 Engines

Domestic LS1 Car Applications:


  • 1997–2004 Corvette, Chevrolet
  • Chevrolet Camaro SS & Z28 1998-2002
  • Pontiac Firebird Formula & Trans Am 1998-2002
  • Pontiac GTO 2004

Domestic LS2 Car Applications:

  • 2005–2007 Corvette, Chevrolet
  • SSR Chevrolet 2005-2006
  • GTO 2005-2006 Pontiac
  • Cadillac CTS-V 2006-2007
  • Chevrolet TrailBlazer SS (2006-2009)
  • Saab 9-7X Aero 2008-2009

Basics of LS1 and LS2 Engine Design

The LS1 engine is a 5.7 L V8 with an aluminium block and heads. It has an OHV, 2 valve/cylinder, 16 valve, pushrod-actuated engine with a bore and stroke of 3.898 in x 3.622 in. The LS2 features the same OHV architecture as the LS1, as well as an aluminium block and heads, but is bored out to 4.000 in x 3.622 in for a total displacement of 6.0 L.

The LS1 was designed to produce 305-350 horsepower and 335-365 pound-feet of torque. The LS2 was rated higher for 395-400 horsepower and 390-400 pound-feet of torque.

Compression on the LS1 was marketed at 10.1:1, but it was actually 10.25:1. The LS2 engine features a higher compression ratio of 10.9:1, a higher lift cam, 15% better intake flow, and 20% better exhaust flow than the LS1.

The LS2 retains the LS1’s six-bolt main caps, 4.40 in centre bore, and deep-skirt casing. Both used steel crankshafts and sequential multi-port fuel injection, with the LS2 having 34 pound-per-hour injectors and the LS1 having 30 pound-per-hour injectors. Because of its smaller displacement, the LS1 will achieve higher fuel economy than the LS2.

The aluminium block of the LS2 Corvette weighs 15 lbs lighter than the LS1 Corvette block. The lighter weight is due to a thinner-walled exhaust manifold, a smaller water pump, and a smaller oil pan. The pan’s baffles have been totally modified to maintain oil flowing through the pickup, and it is wingless rather than “gull-wing” in style. Once again, this redesigned oil pan was only for the LS2 Corvette.

Differences in LS Cylinder Heads between Generations III and IV

The LS-cathedral port cylinder heads are found on both the LS1 and LS2. The LS2 cylinder heads overflow the LS1 heads by a considerable margin and are frequently utilised as an LS1 mod. GM/Chevy designed the LS2 heads to be extremely similar to the LS6 heads, which were, as previously said, a high performance version of the LS1. Beginning April 2001, GM/Chevy equipped the LS1 with LS6 heads. The LS2 is the only Gen IV engine with cathedral heads; all others have superior flowing rectangular-port heads.

The walls of the LS2 exhaust manifold are 1mm (30%) narrower than the LS1, yet weigh less and flow 4% better. The LS1 has two throttle control methods: drive-by-wire in the Corvette and drive-by-cable in all other applications. The drive-by-wire throttle system is used in all LS2 powered vehicles. The LS2 also has a redline that is 500 RPM higher than the LS1, at 6,500 RPM.

The LS2 knock sensors are located outside of the cylinder banks to provide more exact readings than the in-bank LS1 sensors. GM also relocated the cam sensors from behind the intake on the LS1 to the front timing cover on the LS2. The LS1 and LS2 pistons are both made of hypereutectic aluminium, and the LS2 pistons include full-floating wrist pins to prevent piston slap, which was a common problem with the LS1.

Engine Reliability: LS1 vs. LS2

We’ve said it before and we’ll say it again: the Chevy LS engine family is known for its dependability. The entire LS-series is virtually bulletproof in every way, and there are no big widespread issues with them. If properly cared for and maintained, a stock LS1 or LS2 will easily exceed 200,000 miles.

Having said that, neither the LS1 nor the LS2 are fully free of minor flaws, even when upgraded. Piston Ring Seals, Water Pump Failure, Bent Pushrods, Piston Slap (Oil Consumption), and Oil Pump Failure are the most common problems with the LS1.

While this may appear to be a lot of problems for a “reliable” engine, these are not prevalent and do not affect a large number of LS1 vehicles. They are, however, worth mentioning. For a detailed discussion of each of these difficulties, see our LS1 5 Most Common Problems Guide.

The LS2’s primary problems include oil hunger, rocker arm bearing failure, and harmonic balancer failure. The oil hunger problem was more prevalent in early LS2 builds from 2005 to 2006, and it was resolved for subsequent years. After 100,000 miles, the rocker arms of the LS2 are prone to premature wear and failure. There have also been some reports of the LS2 harmonic balancers failing prematurely. For a more detailed breakdown, see the Common Problems and Reliability section of our LS2 engine guide.

Overall, the LS1 and LS2 are nearly identical in terms of reliability, albeit the LS2 did address the LS1’s piston difficulties. Both are great power plants for commencing any build and can be relied on for dependability. They are often used in “LS swaps” into many cars as well as for high-powered projects.

LS1 vs. LS2 Performance and Modifications

Now for the fun part: LS1 vs LS2 performance and mods. The LS2 produces significantly more horsepower and torque than the LS1, but both engines can readily be modified beyond factory power levels. The LS2’s higher displacement will eventually allow it to produce more power, and the block is also believed to be stronger.

If you intend to modify an LS1 or LS2, the improvements are very comparable. In fact, almost all LS engines may be manufactured following a similar method, which we’ll detail below. With these modifications, you can expect to achieve 450-500 horsepower, which is roughly the limit of a naturally aspirated LS engine. If you want to get above 500 horsepower, you’ll need to install a supercharger or turbocharger. More information on a forced induction LS build can be found in our LS2 Supercharger upgrade guide.

The Best LS1 and LS2 Mods

Top LS1 and LS2 modifications:

  • Fresh Air Intake
  • Long-tubular headers
  • increased throttle body size
  • Camshaft Improvement
  • Upgraded Cylinder Heads
  • ECU Programming

Cold Air Intake Gen III/IV LS, Long-tube Headers, Throttle Body

A cool air intake is one of the most typical upgrades for every LS setup. A quality cold air intake will add 5-15 horsepower and significantly improve engine performance when combined with other upgrades. Long-tube headers are another excellent investment because they significantly increase airflow. They can provide 25-40 horsepower when combined with an improved cold air intake. For the best Gen IV headers, see our LS2 header guide.

Installing the LS2 throttle body on an LS1 is a pretty popular improvement. The stock throttle body on the LS1 is 78mm, whereas the LS2 is 90mm. Upgrading the LS1 throttle body to an LS2 throttle body adds 5-10 horsepower and works well with a larger LS2 style intake. The LS2 throttle body is also upgraded, and we have a guide to the top LS2 throttle bodies.

Camshafts and Cylinder Heads from Generations III and IV

After improving the bolt-ons indicated above, many people begin making the engine itself more efficient with an updated camshaft and modified cylinder heads. Cams are terrific improvements for increased top-end horsepower and sound great through the exhaust.

As previously stated, both the LS1 and LS2 use the LS cathedral-port cylinder heads. The LS2 heads have more flow than the LS1 heads and are a direct bolt-on fit. The LS6 heads also fit and outflow the LS1, and GM/Chevy actually began putting the LS6 heads on the LS1 in 2001. Upgrading to better flowing and ported cathedral-port heads is an option for both the LS1 and LS2, but the preferable strategy is to use the rectangular style ports used on the LS3 and LS7 series of engines. At higher RPMs, the rectangular ports overflow the cathedrals and are said to provide more power.

If you decide to go with rectangular-port heads, you’ll also need a new intake manifold, making it a costly improvement. If you do it, you will definitely see some solid improvements with new heads and manifold, possibly up to 20-35 horsepower.

Related : The Ultimate LS6 Engine Handbook

ECU Tuning for the LS1 and LS2

The final mod, LS1 and LS2 ECU tuning, is also one of the best. You should absolutely invest in tuning to ensure that your mods are 1) running securely and 2) performing optimally. Tuners can modify the ECU to optimise factors like fueling and ignition timing for the highest horsepower and torque while remaining dependable.

Most people will tell you that your build is only as good as your tune, and they are correct. If you want your LS build to last, have a tuner look it over once you’ve applied your mods.

LS1 vs. LS2 Comparison

Overall, the LS1 and LS2 are two extremely capable engines capable of massive performance. The LS1 was released over a decade before the LS2, and both engines are rated among the best in the LS series. The LS2 produces more horsepower due to its greater displacement, but the LS1 is more fuel efficient while producing comparable output.

The LS1 and LS2 engines were installed in some of the most notable Corvettes of the late 1990s and early 2000s, when they produced some impressive power figures. In almost every manner, the Gen III LS1 and Gen IV LS2 were vast advances over their Gen II predecessors.