How to Supercharge & Turbocharge GM LS-Series Engines - Revised Edition

INTRODUCTION

A longtime cliché of the automotive world is the phrase they don’t build ’em like they used to. When it comes to the performance capability of the General Motors Gen III/Gen IV engines (commonly known as LS engines), that old adage couldn’t be truer—but not in the traditional sense.

The LS engines aren’t built like the old small-blocks, and that’s a good thing. They’ve proven to be very durable and, with their exceptional airflow capabilities, they are capable of tremendous power with comparatively little work. Add a supercharger or turbo system to one of these compact powerhouses and the dyno numbers go through the roof. In fact, the only factor that holds back an LS engine from making astronomical horsepower is the amount of boost that can be safely shoved through it.

I first encountered the LS engine when the rest of the performance public did in the late 1990s. I was shooting stories at a variety of tuning shops and was, frankly, suspicious of the chassis dyno numbers that were being generated by LS1-powered F-Body cars and Corvettes with bolt-on superchargers. Compared to what the previous GM LT1 engines produced and the amount of time and money the Mustang guys were spending to get power out of their 4.6-liter pony cars, the ease at which 500 rear-wheel horsepower was spitting out of the LS-powered vehicles raised more than a few eyebrows. But, as time progressed and GM increased the displacement and performance range of its well-engineered new engine family, big power has become the norm. In fact, street cars pushing 900 hp and more are not hard to find.

Of course, there’s more than one key required to unlock such supercharged performance. The high-flow attributes of the cylinder heads are tailor-made for big power, but it wouldn’t be possible without easily adjustable factory controllers that enable tuning that are the envy of the Mustang and Hemi camps. The controllers, however, are mostly limited to the fuel they can direct into the engine and, in most cases, that ceiling is around the 1,000-hp level. After that, special injector requirements typically mean a stand-alone aftermarket controller that can handle them. But even then, the engine can still be tuned for streetable, pump-gas drivability.

This book outlines the basics of supercharging and turbocharging, as they’re applied to LS engines. It doesn’t suggest either method of forced induction is better than the other but points out the performance differences, installation challenges, and cost implications between them. There are also great tips for building an engine to support higher-boost combinations.

Whether you’re looking for a simple bolt-on blower kit on an otherwise-stock fifth-generation Camaro or a custom-fabricated twin-turbo system for a Corvette Z06, you’ll find plenty of ideas to ponder within these pages. And you’ll see everything from a $46,000 turbo-kit installation to a homemade turbo system built with cast-off and salvage-yard parts.

If you’re new to the performance world or, more specifically, the corner of it that involves forced induction, do yourself a favor and start browsing the online message boards and forums for ideas, and ask around for recommendations on knowledgeable and reputable tuning shops. Before you spend what will minimally be several thousand dollars on a blower or turbo system for your vehicle(s), you’ll want to know unequivocally that it’s going to deliver the performance you’re seeking.

There’s another old automotive saying: Speed costs money; how fast do you want to go? I believe that can be rewritten for the LS engine this way: Horsepower requires boost; how much can you afford?

Whatever your answer, a little forethought and some careful planning will ensure you’ll come away satisfied when that boost-gauge needle swings into positive manifold pressure territory.

A Note about GM LT Engines

Although architecturally similar to the LS family of engines, the GM Gen V LT engines are not covered in this book. At the time this updated edition was published, aftermarket forced-induction support was mostly limited to bolt-on supercharger kits for popular applications such as the Camaro, the Corvette, and full-size trucks. And while many of the same general theories apply to LT engines, tuning support for them was also somewhat limited at the time of this writing. For these reasons, the author’s focus is strictly on the LS-series.

CHAPTER 1

LS ENGINES AND FORCED INDUCTION

In general terms, and assuming everything else is equal, an internal combustion engine with larger displacement flows more air than a smaller-displacement engine. The engine with the greater airflow makes more power.

Forcing more air into an engine than it naturally draws can substantially increase the output of a smaller engine and give it the power of a larger engine. The forced or ambient air is delivered to the intake manifold at a pressure greater than the outside. It is denser, delivering more oxygen to the combustion chamber. When mixed with the appropriate ratio of additional fuel, the result is a more powerful combustion. That’s the essence of supercharging; whether through an engine-driven supercharger or exhaust-driven turbocharger.

The technology for forced induction supercharging and turbocharging internal combustion engines has been around since the early 20th century, with automotive manufacturers employing the power-boosting effects for more than 80 years. Both supercharging and turbocharging are currently used on dozens of regular production automobiles, and they have been staples of the high-performance world since the close of World War II.

Forced 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 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 equipped for Active Fuel Management and 2010-and-newer versions feature variable valve timing (cam phasing). Manufactured with iron and aluminum cylinder blocks.

6.0L: Used primarily in 3/4-ton and 1-ton trucks, the 6.0L (364 ci) uses an iron block (LY6 or L96) or aluminum block (L76) and aluminum heads with provisions for Active Fuel Management; some are equipped with variable valve timing.

6.2L: Commonly referred to by its L92, L9H, or L94 engine codes, the 6.2L (376-ci) engine uses an aluminum block and heads and incorporates advanced technology, including variable valve timing. The L92 was used primarily as a high-performance engine for the Cadillac Escalade and GMC Yukon Denali.

More About the Vortec 5.3L

With more than 10 years in service in millions of Chevy and GMC trucks, vans, and SUVs, the Vortec 5.3L engine is poised to become the classic 350 small-block of the LS engine family. They are readily available and affordable on the used engine market. Most feature iron cylinder blocks, but some have an aluminum engine block that is about 80 pounds lighter.

Adapting a 5.3L to a hot rod project is easier with Chevrolet Performance’s 5.3L controller kit (part number 19256514), which is tailored to retrofit installations by turning off some of the production features that are unnecessary for a vintage car, including the cylinder-deactivating Active Fuel Management. It covers 2007–2009 applications (non-cam-phased) with the following engine codes:

•  LC9 (2007–2009)

•  LMG (2007–2009)

•  LY5 (2007–2009)

•  LH8 (2008–2009)

•  LMF (2008–2009)

An L94 Vortec 6.2L Gen IV is shown. (Photo Courtesy General Motors)

Chevrolet Performance LS and LSX High-Performance Crate Engines

Chevrolet Performance has offered a number of LS high-performance crate engines based on production LS engines or the racing-oriented LSX series of components, including the cast-iron LSX Bowtie Block. They include:

LS376/515: Based on the LS3, it features the ASA Hot Cam to help push output to 525 hp and 477 ft-lbs of torque. It is designed for a carburetor.

LS376/525: Similar to the LS376/515, this version also uses the ASA Hot Cam, along with an LS3-based induction system and port fuel injection.

LSX376-B8: An economical crate engine that uses the LSX block, LS3 rotating parts, and the LS3 cylinder heads. It is offered without an oil pan or induction system, so that it can be tailored for the project vehicle.

LSX376-B15: Designed to accommodate additional power adders, or boost up to 15 psi, includes forged pistons, forged crank, and six-bolt LSX-LS3 cylinder heads.

LSX454: The displacement of the classic big-block with an all-forged rotating assembly and LSX-LS7 six-bolt cylinder heads. It is rated at 627 hp with a carburetor and 580 with an LS7 fuel-injection system.

Excellent airflow characteristics of the basic LS cylinder head design greatly exploit the benefits of forced induction, as air is easily and quickly moved through the engine. Because of this, a higher-capacity supercharger or larger turbo is often used, when compared to older, previous-generation Chevy small-block designs, to fulfill the airflow capability of a free-flowing LS engine.

LSX454R: A high-compression (13.1:1) version of the LSX454 designed for drag racing, featuring a mechanical roller cam, high-rise intake, and more. It is capable of more than 750 hp.

Supercharging Versus Turbocharging

At their most basic, turbochargers and superchargers are air pumps but with different pumping characteristics. The turbocharger is an exhaust-driven pump that saps no engine power when not making boost. A supercharger is an engine-driven pump that is essentially another component on the accessory drive system and requires a modicum of power to drive, even when it’s not producing much or any boost.

The thermal efficiency, also known as adiabatic efficiency (the amount of combustion energy that is converted to power), is generally greater with a turbocharger system than a supercharger because it recycles a significant amount of exhaust energy to spin the compressor. That exhaust energy is lost to the exhaust system in normally aspirated and supercharged engines. That said, centrifugal and Lysholm (screw-type) superchargers can be up to 85-percent efficient, for comparable efficiency with a turbocharger.

In general terms, superchargers deliver greater power and torque at low- and mid-range RPM levels with nearly full boost available immediately at wide open throttle (WOT). A supercharger’s effectiveness tends to trail off at higher RPM, while turbochargers typically deliver their greatest power contribution at mid- to high-RPM levels, with boost building progressively in line with an increase of engine speed. Turbochargers are also very good at building mid-range torque, and when properly sized, can deliver excellent low-end power too.

There are a number of factors to consider before purchasing a bolt-on system. The performance requirements and engine demands for custom combinations and racing applications are different, but for the enthusiast seeking to add a forced-induction system to his or her vehicle, the following points are the most relevant.

Superchargers (particularly Roots and screw-type blowers) are excellent at delivering low-RPM power, as they are always making at least a minimal amount of boost when the engine is running. That’s because the supercharger is directly linked to the crankshaft via the drive belt. That connection also requires a small amount of horsepower to simply turn the supercharger.

Power Projections

Generally speaking, a supercharger will produce about 6 percent greater horsepower for every pound (0.07 bar) of boost, while a turbocharger will produce about 7 percent greater power for every pound. The turbo’s advantage there is due to the parasitic loss of the supercharger’s drive system. It simply costs some power for the crankshaft to drive the blower. The exhaust-driven turbocharger doesn’t have such a drag.

Turbochargers require no engine power to drive and, therefore, are considerably more efficient than an engine-driven supercharger. However, boost only occurs when the engine RPM rises. At low speeds, particularly off idle, the turbocharger provides no horsepower increase.

The advantage of turbocharging in a racing application is clearly illustrated in this partially constructed fourth-generation Firebird, as two very large turbochargers were adapted to an LS engine. Except for the older, 71-series superchargers used in Top Fuel, Top Alcohol,