The history of Chevy small blocks is more than extensive. Since 1953, the Chevy small block has evolved through countless technical revisions over five distinct generations. Beginning with the third generation of V8 small block, Chevy introduced their LS platform which would go on to be a defining engine series for one of America’s most famous brands.
The LS platform was a new blank sheet design to the Chevy lineup and was characterized by its modular design, pushrod valvetrain, and unparalleled strength. While the Gen III Chevy Small Block was instrumental in establishing the new Chevy V8 formula, the Gen IV platform refined it even further. Two standout engines from the Gen IV era are the 6.0L LS2 and the 6.2L LS3.
The LS2 and LS3 are both fantastic engines in their own right. While they share a similar overall construction, Chevy made some notable improvements to the LS3 that made it the better overall engine. That isn’t to discount the LS2 which is an undeniably great engine in its own right. In this guide, we’ll take a look at the Chevy LS2 vs LS3 debate, highlighting the differences between the two legendary engines.
LS2 vs LS3 Engine Overview
Both the LS2 and LS3 engines are part of Chevy’s Gen IV engine platform, with the LS2 being the first of the bunch. While there wasn’t a whole lot of change between the Gen IV and Gen III platform that preceded it, there were a few notable revisions. The camshaft position sensors and knock sensors were relocated to make room for new technologies. Primary amongst them were the Active-Fuel-Management system and the potential for variable valve timing.
In the two years between the release of the 6.0L LS2 and the 6.2L LS3, some crucial design changes occurred. Most of the differences are directly attributed to increased displacement and higher flow figures from the LS3. The following sections portray how the LS2 vs LS3 battle pans out in terms of history and specs.
Chevy 6.0L V8 LS2 Engine History
As with the LS1 engine that preceded it (not directly, but in spirit), the LS2 was born and bred for the Corvette. The LS1 had been the standard engine for the C5 Corvette since its release in 1996. For the release of the C6 Corvette in 2005, GM wanted to up the power and introduce a more sophisticated powerplant. That’s exactly what they did. As mentioned earlier, the LS2 was the first engine to feature Active-Fuel-Management. Sometimes also called Displacement-On-Demand, the fuel management system had the ability to shut down individual cylinders to only provide enough power for a given situation. This reduced fuel consumption while also infuriating some Corvette purists.
In actuality, the block design of the LS2 didn’t change as much as Chevy had people believe. The Gen IV LS2 block was remarkably similar to the previous Gen III design which made many parts interchangeable between Gen III and LS2 engines. The similarity between engines was a blessing to some in the aftermarket community who were already familiar with the design of older parts.
The LS2 V8 wouldn’t stick around for long, only being offered in the C6 Corvette for 3 years. Outside of the Corvette, the LS2 was also used in Cadillac, Pontiac, and even Saab marks before finally being phased out in 2009 in favor of the LS3.
Chevy LS2 Specs and Applications
|Engine||Chevrolet 6.0L LS2 Engine|
|Displacement||6.0L (364.1 cid)|
|Valvetrain||Pushrod OHV 2 Valves Per Cylinder|
|Bore x Stroke||4.00 inches (101.6 mm) x 3.62 inch (92mm)|
|Weight||Long Block ≈ 400lbs|
|Horsepower||400 hp @ 6,000 RPM|
|Torque (lb-ft)||400 lb-ft @ 4,400 RPM|
As you can see, the LS2 is no slouch of an engine. Producing 400 horsepower and 400 lb-ft of torque, the LS2 puts 50 horsepower on its LS1 predecessor. A lot of that extra power comes from the LS2’s extra 0.3L of displacement. The LS2 also featured new exhaust manifolds which reduced weight and flowed better. To keep overall weight as low as possible, both the LS2 cylinder heads and block were constructed out of aluminum.
In comparison to the LS1, the LS2 also features a larger bore diameter of 4.00 inches compared to a 3.89 inch bore. While it might only seem like a small difference, the increase in bore diameter multiplied by 8 results in 0.3L more displacement. Due to changes in piston design, the LS2 also had a higher compression ratio than the LS1. The 5.7L V8 had a compression ratio of 10.2:1 while the LS2 has a compression ratio of 10.9:1.
What Cars Used The Chevy LS2?
- Chevrolet C6 Corvette (2005-2007)
- Chevrolet SSR (2005-2006)
- Chevrolet Trailblazer SS (2006-2009)
- Cadillac CTS-V (2006-2007)
- Pontiac GTO (2005-2006)
- Saab 9-7X (2008-2009)
Chevy 6.2L V8 LS3 Engine History
When the LS3 took the reigns from the LS2 as the engine in the base C6 Corvette, it came with a lot of promise. The LS3 really acts as a refined and perfected version of the 6.0L V8 that preceded it. In addition to the added displacement, the LS3 also featured key performance design changes. For example, the LS3 switched from the cathedral port design from previous LS engines in favor of a higher flowing rectangular port design.
Other Corvette-specific options played a role in boosting the performance of the LS3 engine. Primary amongst them was the C6’s optional dual-mode exhaust system. The advanced exhaust design acted as a silenced exhaust during low RPM driving but opened up to be unrestricted during performance driving. The upgraded system would yield around 6 horsepower and 4 lb-ft of torque over the standard system.
Compared to the LS2’s lifespan, the LS3 saw continued use from multiple manufacturers for an extended period of time. From the time that the LS3 was first placed in the 2008 C6 Corvette, it would make an appearance in a number of performance vehicles until it was discontinued for use in commercial applications in 2017. Throughout its nearly 10-year run, the LS3 was used in the Corvette, Camaro, Pontiac G8, Chevy SS, and multiple Holden vehicles in Australia. The LS3 can still be purchased new as a crate engine.
Chevy LS3 Specs and Applications
|Engine||Chevrolet 6.2L LS3 Engine|
|Displacement||6.2L (376 cid)|
|Valvetrain||Pushrod OHV 2 Valves Per Cylinder|
|Bore x Stroke||4.06 inches (103.1 mm) x 3.622 inch (92mm)|
|Weight||Long Block ≈ 418 lbs|
|Horsepower||430 /436 hp @ 5,900 RPM|
|Torque (lb-ft)||424 / 428 lb-ft @ 4,600 RPM|
The most immediate change between the LS3 and the LS engines that preceded it (at least in the Corvette) is displacement. Due to the increased 103mm bore diameter, the LS3’s displacement was simultaneously increased by 0.2L. While the overall displacement of the LS3 was increased, compression dropped to 10.7:1 due to differences in cylinder head design.
Speaking of cylinder heads, outside of displacement, that is where the majority of serious differences came into play between the LS2 and LS3. Utilizing cylinder heads sourced from the L92 Vortec truck engine, the LS3 has higher flow figures and features larger intake and exhaust valves. The 6.2L LS3 also features a more aggressive camshaft with increased lift, which also necessitated improved rocker arms and stronger valve springs.
The LS3 followed the LS formula that had been outlined by previous generations and continued to build on it. The LS3 features a slightly stronger block than the LS2, while also making use of the nodular iron crankshaft, hypereutectic aluminum pistons, and six-bolt main construction that have made LS engines synonymous with strength and reliability for decades. As with most engines in the LS family, the LS3 can hold up to serious abuse. Some LS3 owners find that stock-internal LS3 can withstand around 800 horsepower. That’s nearly double their stock output.
What Cars Used The Chevy LS3?
- Chevrolet C6 Corvette (2008-2013)
- Chevrolet SS (2014-2017)
- Chevrolet Camaro SS (2010-2015)
- Pontiac G8 (2009)
LS2 vs LS3 Differences
While the LS formula stayed very similar between engines of the same generation, some obvious and some not-so-obvious changes were made between engines. There are some important distinctions between the LS2 and LS3 that make the LS3 a higher performing and better breathing engine.
Moderate changes were made to the short block of both the 6.0L and 6.2L LS engines, mostly focused on strength and improved piston design. Most of the differences between the LS2 and LS3 can be found in their cylinder head designs. The changes made to the 6.2L LS3 cylinder head allow it to flow better than the LS2, increasing power. A higher performance cam and larger valves were fitted to the LS3 V8, which also improve performance. Chevrolet was also forced to alter the LS3 intake manifold design due to the difference in port design.
LS2 vs LS3 Short Block Differences
While the displacement difference between the LS2 and LS3 is immediately noticeable between the two short blocks, there are other notable changes to the block design, piston design, and crankshaft design.
While still similar to the LS2 block, the LS3 bottom end is actually borrowed from the L92 Vortec truck engine. The L92 used the same deep-skirted, aluminum, six-bolt main design that made the LS platform famous. The main bearing webs of the LS3 were strengthened which contributed to a 20% increase in bottom end strength compared to the LS2.
Both the LS2 and LS3 feature hypereutectic aluminum pistons which are both light and strong. However, there are differences between the two concerning piston and piston ring design. Due to the increased cylinder bore diameter of the LS3, larger pistons were also required. As the LS3 shares a block design with the L92, the pistons are almost identical as well, with the LS3 pistons simply not retaining valve reliefs present on the L92 pistons. LS3 piston rings were also optimized to provide better piston cooling and oil control.
Overall, LS2 and LS3 crankshafts are nearly identical. They are both made from nodular iron making them incredibly strong. The only significant difference between them is a different counterweighting solution as the LS3 crankshaft is heavier.
LS2 vs LS3 Cylinder Heads
A vast majority of differences between the Chevy LS2 and Chevy LS3 can be found in their cylinder head designs. Most of the changes can be distilled into differences between intake and exhaust port shape, location, and volume. These differences make for a higher flowing head on LS3 applications.
While the LS2 featured a cathedral port head design shared with the LS1 and LS6, the LS3 switched to a rectangular design. Chevy achieved this port shape change by relocating the pushrods slightly to allow for a larger surface area for the ports to occupy. The LS3’s rectangular ports are also larger overall, with an intake port volume of 257cc and an exhaust port volume of 86cc.
As a result of the larger ports, the LS3 also utilizes larger intake and exhaust ports. In comparison to the LS2’s 2.0” intake and 1.575” exhaust valve diameters, the LS3s valves are slightly larger at 2.165” and 1.59” respectively. The changes to the LS3’s cylinder head result in a 17% increase in intake port flow and a 6.2% increase in exhaust port flow over the LS2’s.
Outside of the cylinder head port differences, the combustion area of the LS3 head was also changed to improve airflow characteristics while also increasing its size in the process. The increased internal area allows air and fuel to mix better which allows for better combustion, but it is also one of the main contributors to the LS3’s decreased compression compared to the LS2.
Chevy also focused on reliability with the LS3 cylinder head design by strengthening the head structure at the exhaust manifold flanges, improving the water jacket core for better thermal efficiency, and implementing stronger valve seats.
Chevy 6.0L vs 6.2L Cam and Valvetrain Differences
There are also a few changes to the camshaft and valvetrain between the LS2 and LS3. Both the LS2 and LS3 camshaft designs are based on a design that the LS6 introduced. The LS3’s more aggressive 204/211 .551/.525 117 grind makes it the superior performance cam compared to the LS2 or LS6 cams. Lobe separation was increased by a degree to prevent excessive overlap.
Due to the adjusted geometry of the LS3 camshaft, rocker arm placement was also altered slightly. They are slightly offset, which also adjusts the position of the pushrods. The main reason for this was to increase the size and alter the location of the LS3 intake ports. LS3 intake valves were also changed, with a lengthened and hollow stem.
LS2 vs LS3 Intake Manifold
As we discussed in the previous section, Chevy opted to change the intake and exhaust port shape to a rectangular design. They also moved the position of the ports. As a result, the LS3 intake manifold also needed to be changed to accommodate the new port design. While the real differences between the two manifolds aren’t immediately apparent beyond the revised port shape, Chevy did make some other significant changes.
The way to improve an intake manifold is to get rid of as many restrictions as possible. This allows for air to follow an easier path to the head without as much turbulence. That’s exactly what Chevy did with the LS3 head. Restrictions were reduced by around 2-3% which made the LS3 intake manifold flow marginally better than the LS2 intake manifold. The LS3 intake also features a newly designed webbing structure to improve stiffness.
Beyond those differences, the LS2 and LS3 intake manifolds share a very similar overall shape. While it is confirmed that the LS3 intake manifold has better flow figures than the LS2 counterpart, the amount is contested. It is also important to note that LS2 and LS3 intake manifolds aren’t interchangeable. That is unless you opt to swap cylinder heads as well. An LS3 cylinder head will bolt to an LS2 block at which point the intake could also be swapped.
Chevrolet LS2 vs LS3 Engine Summary
While the Chevy LS2 and LS3 are both titans of their time, the design changes made to the LS3 make it the more popular and better-performing option. While the two Chevy engines have more in common than they do differences, the LS3 design changes Outside of the displacement difference, most of the important design changes can be found in the cylinder head design of the LS3, which features a rectangular port design in favor of the previously employed cathedral port design. Many of the changes between the two are directly related to the LS3’s higher displacement. As such, the LS3 required larger pistons and a new intake manifold to work in conjunction with the updated cylinder head design.
In terms of performance potential, at the end of the day, both are LS engines. Both the LS2 and LS3 are capable of producing similar power figures in factory form. With that being said, the LS3 will ultimately outperform the LS2 due to better flow and higher displacement. While the LS3 is the performance choice, it isn’t as budget-friendly as the LS2. Since the LS2 is older and in less demand, it is easier to source one for a lower price. That makes the LS2 a solid option for a budget-conscious build
The LS2 and LS3 are good engines to compare due to the fact that they were released so close to each other. Despite the relatively short duration between the LS2 and LS3s placement in the Corvette, Chevy certainly moved the LS platform forward with the 6.2L LS3.
If you enjoyed this article and are looking for more LS content, check out our LS1 vs LS3 Engine Guide. As always, safe driving!