The essence of this book is to provide the performance car enthusiast interested in supercharging with a body of information that can be used to evaluate system designs, whether of a factory supercharger system or an aftermarket kit. This book is also intended as a design guide for the hobbyist who wants to build his own supercharger system. Three viable methods exist to acquire a supercharged vehicle:

• buy an OEM-supercharged automobile• buy an aftermarket kit, if available, for your specific application• build your own supercharger system

The rationale behind the decision that suits your needs and requirements best is no more than a logical summary of the following:

• What is the intended use of the vehicle?• What is the legality with respect to state and federal law and the year

of the car?• How much power is required?• Is fear of a failure such that a factory warranty is required?• Can you make a reasonable judgment with respect to the engineer-

ing of an aftermarket kit?• Do you have the skills, time, patience, and equipment to build your own?

The serious driver of supercharged machinery, of less than six-digit means, has not been catered to by the OEMs of today. While performance abounds in automobiles from Camaros and BMWs to Volvos and Vipers, only Mercedes sees fit to produce an affordable supercharged sports car. One can purchase Buicks and Pontiacs and Millenias sporting blowers, but these vehicles do not meet the author’s idea of exhilarating motoring. True, there are blown V-8 Aston Martins and Jaguars, but these are largely unattainable vehicles. Therefore, although they are technically interesting, their presence in the motoring world is of no value to us middle-class leadfoots. Unless your tastes lie along the lines of a mildly rapid family hack, enjoy-ing the fun of a supercharged automobile will tend to push you in directions other than the offerings of the OEMs.

If you buy a supercharged OEM vehicle and want to go fast, the first step in pursuing more performance is a complete analysis of the system design. Chapter

2 Acquiring a Supercharged Vehicle

13

OEM-Supercharged Automobile

14 supercharged!

16, Testing the System, is your starting point. With those data accumulated and analyzed and the weak links identified, you can set out to find the necessary com-ponents to improve the system. Keep in mind that the issue here is to improve the system’s efficiency, thereby opening up the potential for huge gains in power. Increasing boost pressure is also a consideration, but without improvements to the system’s efficiency, this path to power is fraught with serious mechanical risk.

Once the system has been tested and the merit of each feature has been determined, start the improvement process with the weakest link. Here is where foresight becomes important. For example, an intercooler that loses only 2 psi at the factory-rated boost can be judged okay. It is okay, but only for the factory-rated boost. Likely it will lose 3 or 4 psi at any significantly increased airflow. That kind of loss is not acceptable.

Fig. 2-2: The Eaton super-charger integrated into a Chevy small-block intake manifold by Magnuson shows the simplicity of the basic hardware—augment-ed by the self-lubricating Eaton blower.

Fig. 2-1: For decades, the classic blown street rod has enjoyed the combo of a B&M Roots blower, Holley carbs, and the small-block Chevy.

Here’s where the action is taking place. Those Camaros, Vipers, BMWs, Mustangs and even little Mazda Miatas have a plethora of kits and components available for mild to wild performance. The ten- and eleven-second street car can be built today from components engineered in the aftermarket.

The purchase of an aftermarket supercharger system is an ideal occasion to employ this book as the guide it is intended to be. An investigation is necessary to determine the system that will meet your needs. Determine your objectives, then decide what type of supercharger most closely meets those needs.

Before a reasonable decision can be made, answers to a variety of questions must be both sought and understood. The following samples will get you on the right track:

Does the system provide a correct air/fuel ratio at all operational conditions?

The air/fuel ratio is a basic building block of a supercharger system. It needs to be maintained over the boost range that the manufacturer claims for the kit. It is not to be expected that the air/fuel ratio will stay correct if the system’s design limits are exceeded. In all circumstances, it is necessary to avoid discussing “fuel enrichment.” Either an air/fuel ratio is correct or it isn’t—no “enrichment” required.

chapter2:acquiringasuperchargedvehicle 15

Fig. 2-3: This Vortech sys-tem for the 2-valve ’96–97 Mustang illustrates the vari-ety of components needed to call a kit “complete.”

Aftermarket Supercharger Kit

Fig. 2-4: The early produc-tion Rotrex blowers were specifically for small-dis-placement engines, like this four-cylinder, 2.0-liter VW.

16 supercharged!

Does the system provide a margin of safety on detonation?

The attempt here is to determine whether the system installed and operated per instructions will yield useful boost and not be subject to detonation problems.

Does the system provide the necessary thermal controls to operate at the stated boost pressures?

Ask for a description and explanation of these controls.

What efforts are extended toward quality control?

Fit and finish are obvious. Material selections, methods of welding, surface finishes, and other fabrication procedures should also be checked out.

Do the components carry a reasonable warranty?

Although warranties on performance-oriented components are fre-quently subject to severe limitations, the buyer cannot be hung out to dry. It is useful to discuss with the kit maker the warranty limitations and procedures necessary to establish the best warranty terms.

Are proper instructions offered with the system?

Instructions should provide all the necessary information to install, check out, and subsequently operate and service the supercharged vehicle.

Will consulting be provided after the sale?

This is where the maturity of a supercharger system manufacturer will truly show.

If the system is to be used on a public highway, is it designed with all emis-sions-related equipment in proper order, and/or is the system on EPA- or CARB exemption-order status?

In all states, the emission question will be the most important one.

When the answers to the above questions are satisfactory, it is time to get down to the fun details, such as compressor efficiency with respect to the system flow rates and boost pressures.

Fig. 2-5: The Kenne Bell shops produced this very OEM-appearing Ford F150 twin-screw assembly.

All kit makers will try to represent their systems as the most powerful. The accuracy of these claims is a different story. The advent of the chassis dyno made it look, for a short period, as though manufacturers would publish legitimate power curves. Unfortunately, in some cases, these have evolved into just another way of stretching a point. For example, a dyno graph may show a blower run at 15 psi when the kit is sold to run at 6 psi. And there are many more clever tricks than just running the wrong boost pressure.

Any reasonably able fabricator should have no serious difficulty designing and building his own supercharger system. Forethought, planning, calculating, sketch-ing, and measuring, all done in considerable detail, will be the keys to the success of the project.

Perhaps the single greatest problem facing the do-it-yourselfer is avoiding get-ting stuck. Getting stuck is the phenomenon of “You can’t get there from here.” For example, you can’t ever hope for an emissions-clean 10-second street car if you build a draw-through carb type. Trying to adapt a used blower from a 3.8-liter Buick to a 454 big-block will decidedly put you in a position where you are stuck. Avoid going down these paths leading to “stuck.”

The first requirement is to determine the power level desired. Translate that figure into a boost pressure necessary to get the job done. That, in itself, will determine the equipment needed. The remainder of the project is the sum of the experience contained in this book.

chapter2:acquiringasuperchargedvehicle 17

Fig. 2-6: Centrifugal blow-ers can easily be adapted to older, carbureted engines. This ATI system is intended for blow-through carb applications.

Building Your Own Supercharger System

Fig. 2-7: This compact design integrates the super-charger into the intake manifold for the six-cylinder Jeep 4.0.

18 supercharged!

What is a reasonable price to pay for a supercharger system?

The lowest-priced system that offers: • a correctly sized supercharger • a correct air/fuel ratio under boost • proper ignition timing • proper thermal controls • a margin of safety on detonation • quality componentsSuch a system can put together a good argument for being the best value. It is popular to believe that you get what you pay for, but there are super-charger kits costing nearly $7,000 that do not have a correct air/fuel ratio. Conversely, well-designed kits are available for less than $2500. A reasonable price? This must remain the prospective buyer’s decision, based on a thorough knowledge of what he gets for his money.

What paperwork should be included with a supercharger kit?

Instructions and warranty are self-explanatory. Cautions and operating procedures must be well detailed and conservative.

What are the warranty implications of installing a supercharger in a new automobile?

All factory warranty on drivetrain components will be voided. There are, however, several circumstances to consider. You can purchase an after-market warranty to cover your vehicle for all non-supercharger-induced or -related problems. It is currently in vogue to sell these policies with supercharger systems under the intended misconception that your drive-train is warranted against “supercharger-induced” failures. Not so.If one breaks his supercharged engine, it is not going to be paid for by anyone’s warranty—exactly the same situation as waiting until the fac-tory warranty expires and then adding the supercharger. Which means that waiting out the factory warranty before installing a supercharger accomplishes nothing except insuring that the mechanism is one-third used up pre-supercharger. Furthermore, it eliminates the fun of ever owning a nice new automobile with enhanced power.

And Furthermore . . .

Fig. 2-8: A Dodge V-10 kit from Carroll Supercharging

It is rare for a modern automobile to have an engine/drivetrain prob-lem within the warranty duration. Those problems that do appear are generally minor and will likely cost under a hundred dollars to repair. To preserve the warranty for many thousands of miles to avoid a pos-sible hundred-dollar component failure rather than enjoying the extra performance seems to me the poorer choice. To assuage your concerns, call the car maker’s regional office and discuss with a service rep the areas of the drivetrain that have been a warranty problem.

Will I have to buy anything else to supplement the supercharger?

Wow, what a loaded question. What this usually boils down to is the difference between a system that’s “complete” and one that’s “com-prehensive.” In the world of supercharger kits, “complete” means that all the parts arrive in the box, so you don’t have to make any trips to the hardware store or call the maker about missing pieces. You’d be surprised how often this happens. Whether the kit was designed with the components to do the job is another story. “Comprehensive” means that the kit includes a fuel sys-tem, detonation controls, and boost gauge. If a kit advertised as “complete” arrives minus a few pieces, this is a tragedy that can be set right in a few days at most. But if the kit is poorly designed, having all the pieces and more is no consolation.

chapter2:acquiringasuperchargedvehicle 19

established 1950Automotive Reference™

Bentley Publishers, 1734 Massachusetts Avenue, Cambridge, MA 02138-1804 USATel: 617-547-4170 • Toll Free: 800-423-4595 • Fax: 617-876-9235http://www.bentleypublishers.com/contact-us

SuperchargedDesigning, Testing and Installation ofSupercharger Systems

by Corky Bell

Price: $34.95Bentley Stock Number: GSUPPublication Date: 2001.11.01ISBN: 978-0-8376-0168-7Softcover, 7 7/8 in. x 10-3/8 in.Case quantity: 10346 pages, 165 photos, illustrations and diagrams

Corky Bell, the author of the best selling Maximum Boost, has done it again with the publication of Supercharged! Design, Testing and Installation of Supercharger Systems. Superchargers have become one of the most popular performance bolt-on products for all engine sizes-from the diminutive, but powerful, Honda and other import four cylinder engines, to Porsche and BMW engines, and Detroit’s V6s and V8s. However, bolting a system on that works to the enthusiast’s expectations and at the same time is reliable has been a “mystic art.” No longer!

In this book, Corky gets down to the hands-on application of his information. In the chapter “Implementing the Design” he takes us step by step through the calculations, design, installation, and testing of an original supercharger system for a BMW Z3 that ends up producing 10 more horsepower than originally estimated to propel the car down the drag strip in the mid-14 second range. In the next chapter, “Installing a Supercharger Kit,” he shows us how to install and dyno check a Toyota off-the-shelf factory system on a Toyota pick-up truck. A suppliers list and glossary are also included at the end of the book.

The supercharger has become the most powerful piece of bolt-on performance equipment. For anyone interested in installing a supercharger system, or just in learning about them, Supercharged! Designing, Testing, and Installing Supercharger Systems is a must have book!

Table of Contents

1. The Purpose of Supercharging2. Acquiring a Supercharger Vehicle3. The Physics of producing Power4. The Balance of Heat5. The Roots Supercharger6. The Centrifugal Supercharger7. The Screw Compressor Supercharger8. Intercooling9. Intake Manifold10. Electronic Fuel Injection11. Events in the Chamber12. Secondary Components13. Mounting the Supercharger14. Drive Mechanisms15. Preparing the Engine16. Testing the System17. The Outer Limits of Power18. Designing a Supercharger System19. Implementing the Design20. Installing a Supercharger Kit

Fig.16-1: The five points of interest for temperature and pressure measurement.Chapter 16: Testing the System

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Fig. 6-12: The good, the bad, and the ugly: where the intersection of the pressure-ratio and airflow lines should (and shouldn’t) fall for highest thermal efficiency.Chapter 6: The Centrifugal Supercharger