induction has been used to boost the power of engines for decades. Hot rodders made it a common practice after World War II, and engine-driven supercharging became popular on street and drag racing cars.
One of the most popular performance engines of today is GM’s “LS” family. As technology progresses, it continues to become an increasingly popular choice for forced induction. Since its introduction in the late 1990s, the GM Gen III/Gen IV engine family (commonly known as LS) has proven itself as a capable foundation for high-performance engines. By relying on a conventional, cam-in-block configuration with the benefit of exceptionally high-flowing cylinder heads, the LS engine delivers tremendous torque at low RPM and great power at the upper rev range.
General Motors experimented with turbocharging in the early 1960s and perfected it in the mid-1980s by combining it with electronic fuel injection. The turbocharged and intercooled V-6 engine of the 1986–1987 Buick Grand National outperformed most V-8s when new.
Forced induction was attempted with early LS engines, often with mixed results. Early adopters of supercharging and turbocharging typically encountered tuning trouble when they tried to work around the factory engine-control system and crank-triggered ignition system. That, and the greater airflow capability of the LS heads, made it difficult to match a supercharger or turbocharger to the engine. Often, the blowers ran out of breath.
In the early 1990s, General Motors adopted supercharging for a number of V-6-powered midsize and large passenger cars, including the Pontiac Grand Prix. The automaker used a Roots-blown 3.8L engine with a supercharger supplied by Eaton. The engines proved exceptionally robust and powerful, spawning a cult of enthusiasts who continue to modify and race the vehicles.
But much has changed in the years since tuners first experimented with supercharging the LS engine. Properly sized superchargers and turbochargers, relatively easy tuning, and other elements have made supercharging or turbocharging an LS-powered vehicle a simple, yet highly effective, method of generating a dramatic increase in power.
Of course, General Motors itself has adopted supercharging as a regular production method of building big power. The C6 Corvette ZR1’s LS9 engine and the Gen II Cadillac CTS-V’s LSA engine used Roots-type superchargers to make 638 hp and 556 hp, respectively. The engines were also designed with specific components to support forced induction.
GM’s relationship with Eaton superchargers reached its zenith in 2009 with the introduction of the factory-blown Corvette ZR1. With its sixth-generation supercharger atop its 6.2L V-8, the ZR1 is rated at 638 hp. It is the most powerful production car ever produced by General Motors. (Photo Courtesy General Motors)
Along with the Corvette ZR1, General Motors launched another factory-supercharged car in 2009: the Cadillac CTS-V. Like the ZR1, it featured a sixth-generation Eaton supercharger on a 6.2L engine, but the supercharger was smaller, resulting in only 556 hp. (Photo Courtesy General Motors)
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
