LS Family Tree
The engine family commonly called the LS series debuted in 1997. General Motors called it the Gen III Small-Block with the iron-block versions in trucks and the all-aluminum LS1 version introduced in the then-new C5 Corvette. A year later, the LS1 replaced the Gen II LT1 Small-Block in Camaros and Firebirds. The LS1 displaced 5.7 liters, similar to the previous-generation small-block, but the cubic-inch measurement differed slightly: 346 for the LS1 versus the traditional 350.
An LS1 5.7-liter Gen III is shown. (Photo Courtesy General Motors)
In 1999, the Gen III platform spawned the higher-performance LS6 that was standard in the Corvette Z06. In 2005, the Gen IV branch of the LS family was born, differing from the Gen III with cast-in provisions for fuel-saving cylinder deactivation, larger displacements, and revised camshaft sensing. The performance versions of the Gen IV include the LS2, LS3, LS9 supercharged, and LS7.
This is an LS3 6.2-liter Gen IV. (Photo Courtesy General Motors)
GM has continued to refer to its modern V-8 engine family as Gen III and Gen IV, but to the enthusiasts who quickly grasped the tremendous performance potential of the engines, every engine based on the platform is nicknamed “LS.” The range of production engines from the LS platform is wide. On the truck side, iron-block engines have included 4.8L and 5.3L versions, as well as all-aluminum 6.0L and 6.2L premium engines. Car engines include 5.3L, 5.7L, 6.0L, 6.2L, and 7.0L displacements, including some configured for front-wheel drive.
Gen III Versus Gen IV
Despite some significant differences between Gen III and Gen IV cylinder blocks, all LS engines share common traits that include:
• 4.400-inch bore centers (matching the original small-block)
• Six-bolt, cross-bolted main bearing caps
• Center main thrust bearing
• 9.240-inch deck height
• Four-bolts-per-cylinder head bolt pattern
• 0.842-inch lifter bores
• Distributorless, coil-near-plug ignition system
The most distinguishing differences between Gen III and Gen IV cylinder blocks are larger bores (on some engines), different camshaft position sensor locations (front timing cover area on Gen IV blocks and top-rear position on Gen III blocks), and on most Gen IV blocks, cast-in provisions for GM’s Active Fuel Management cylinder deactivation system.
There is great interchangeability between all LS engines, including between Gen III and Gen IV versions. Cylinder heads, crankshafts, intake manifolds, and more can be mixed and matched, but the devil is in the details. Not every head matches every intake manifold and not every crankshaft works with every engine combination. Will Handzel’s How to Build High-Performance Chevy LS1/LS6 V-8s is a great reference source that outlines the more specific differences and interchangeability among Gen III-based engines.
LS1/LS6
LS1 5.7L (346-ci) engines were produced between the 1997 and 2004 model years in the United States (Corvette, Camaro, Firebird, and GTO) and stretching into 2005 in other markets (primarily Australia). The LS6 was introduced in 2001 in the Corvette Z06 and was manufactured through 2005, where it also was found in the Cadillac CTS-V. The LS1 and LS6 share a 5.7L displacement, but the LS6 production engine uses a unique block casting with enhanced strength, greater bay-to-bay breathing capability, and other minor differences. The heads, intake manifolds, and camshaft also are unique LS6 parts.
LS2/L76/L77
In 2005, the LS2 6.0L (364-ci) engine and the Gen IV design changes debuted. In GM performance vehicles, it was offered in the Corvette, GTO, and even the heritage-styled SSR roadster. It was the standard engine in the Pontiac G8 GT (L76) and is now the V-8 offered in the Chevrolet Caprice Police Pursuit Vehicle (L77). This engine is one of the most adaptable in the LS family, as LS1, LS6, LS3, and L92/L94 cylinder heads work well on it.
LS3/L99
Introduced on the 2008 Corvette, the LS3 brought LS-based performance to an unprecedented level: 430 hp from 6.2L (376 ci). The LS3 block not only had larger bores than the LS2 but also a strengthened casting to support more powerful applications, including the LS9 supercharged engine of the Corvette ZR1. The LS3 was also the standard engine in the fifth-generation Camaro SS and was offered in the Pontiac G8 GXP. The L99 version was equipped with GM’s fuel-saving Active Fuel Management cylinder deactivation system and was standard on fifth-generation Camaro SS models equipped with an automatic transmission. A unique version of the LS3 used in some C6 Corvette Grand Sport applications incorporated a dry-sump oiling system.
LS4
Perhaps the most unique application of the LS engine in a car, the LS4 was a 5.3L version used in the front-wheel-drive Chevrolet Impala SS and Pontiac Grand Prix GXP. The LS4 had an aluminum block and unique, low-profile front-end accessory system, including a “flattened” water pump, to accommodate the transverse mounting position within the Impala and Grand Prix. It was rated at 303 hp and 323 ft-lbs of torque.
LS7
A legend in its own time. The LS7 was the standard engine in the C6 Corvette Z06 and fifth-generation Camaro Z28. Its 7.0L displacement (427 ci) made it the largest LS engine offered in production vehicles. Unlike LS1/LS6, LS2, and LS3 engines, the LS7 uses a Siamese-bore cylinder block design, which was required for its big 4.125-inch bores. Competition-proven heads and lightweight components, such as titanium rods and intake valves, made the LS7 a street-tuned racing engine with 505 hp. Chevrolet Performance’s crate engine reflects the Camaro Z28 version, which features a unique Tri-Y exhaust manifold design.
LS9
The LS9 was the 6.2L supercharged and charge-cooled engine of the C6 Corvette ZR1, rated at 638 hp. The LS9 used a strengthened 6.2L block with stronger roto-cast cylinder heads and a sixth-generation 2.3L Roots-type supercharger. Like the LS7, it used a dry-sump oiling system.
Pictured is an LSA 6.2-liter supercharged Gen IV. (Photo Courtesy General Motors)
LSA
This supercharged 6.2L engine powered the 2009–2015 Cadillac CTS-V series and the 2012–2015 Camaro ZL1. Although similar to the LS9 in design, it was built with several differences, including hypereutectic pistons versus the LS9’s forged pistons and a smaller 1.9L supercharger. It also has an eight-bolt flywheel versus the LS9’s nine-bolt pattern. The LSA has a unique charge-cooler design on top of the supercharger (with differences between the Cadillac and Camaro ZL1 applications). It was rated at 556 hp in the CTS-V and 580 hp in the Camaro ZL1. Chevrolet Performance’s crate engine reflects the Camaro ZL1 application.
Gen III and Gen IV Vortec Truck Engines
Although performance car engines have typically carried “LS” designations, truck engines built on this platform have been dubbed “Vortec.” They are generally distinguished by iron cylinder blocks and smaller displacements than car engines. Interestingly, a 5.7L Vortec “LS” engine has never been offered. Here’s a quick rundown of production LS truck engines.
4.8L: The smallest-displacement LS engine (293 ci); it uses an iron block with 3.78-inch bores and aluminum heads.
5.3L: The most common LS truck engine, it uses the same iron block with 3.78-inch bores as the 4.8L, but with a larger, 3.62-inch stroke (327 ci). Later versions