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