The 2005 Specialty Equipment Market Association (SEMA) show in Las Vegas may be over for another year, but its impact in the automotive repair market is expected to carry on through 2006. Earlier this month, future automotive technology and the industry’s hottest automotive trends were unveiled to more than 2,000 manufacturers in categories ranging from racing and performance to mobile electronics and restyling at the Las Vegas Convention Center. And, after nearly 40 years of SEMA shows, the event continues to be an industry barometer for consumer tastes that may ultimately filter into your shop.

“The notion of personalization and customization has started to take hold among mainstream automotive consumers,” said Peter MacGillivray, SEMA vice president of marketing and communications, adding that “the $31 billion industry is driven by enthusiast-based businesses that utilize the show to attract attention to their new products.”

In this article, we’re going to look at the induction system upgrades that can give your customers’ small engines a big increase in power and probably yield more bang for their buck than internal engine modifications. The kind of upgrades we’re talking about are bolt-on supercharger and turbocharger kits, along with intake manifolds, oversized throttle bodies, cold air intakes and nitrous oxide systems. Cruising through the SEMA show, these items can be found from a wide range of aftermarket suppliers and manufacturers. The best part is that these components can add profits for shops that are geared up to install them for their customers.

Know Your Market
Unlike the traditional repair business where you have to wait for parts to wear out on your customers’ vehicles before you can replace anything, the supercharging performance market offers immediate service opportunities. Owners who want to squeeze more power out of their four-cylinder and V6 engines don’t want to wait until the engine needs major repairs. They want more power now and are willing to pay someone like you big bucks to install the kind of performance products that will transform their anemic little economy car into a rip-snorting street screamer.

However, making performance engine modifications obviously requires two things: experience and interest. If you’re not into racing, have had no firsthand experience modifying engines and have never gone through the learning curve of all the things that can go wrong when modifying an engine, this market may not be for you. On the other hand, if your traditional repair business has been lackluster and you’re looking for a new profit center or specialty that could attract new customers and generate additional revenue, installing high-performance engine parts might be the answer. Most shops that promote this type of work are booked solid.

Heavy Breather
A naturally aspirated engine can suck in only so much air with every intake stroke of its pistons. As rpm increases, the volume of air ingested by the engine goes up, but breathing efficiency starts to drop off due to restrictions in the intake plumbing, heads and valves. The amount of power produced by the engine ultimately depends on how much air it takes in and how efficiently it breathes.

Since four-cylinder engines don’t have a lot of displacement, a couple of liters aren’t a lot to work with. One way to make a little engine breathe big is to give it a bigger set of lungs with a blower. Forcing air into the engine under boost pressure increases air flow and breathing efficiency.

It doesn’t take much boost to make a big difference in horsepower and torque. Six or seven pounds of boost pressure generated by a supercharger will typically boost an engine’s power output 40% to 50% or more! Want more power? Just turn up the boost pressure.

One aftermarket supplier of Honda supercharger kits we interviewed said their bolt-on system takes a stock 1999 Honda Civic Si from 160 hp up to 277 hp measured at the flywheel. That’s an improvement of more than 100 horsepower using seven to eight pounds of boost and an air-to-water aftercooler on an otherwise stock engine.

The main difference between superchargers and turbochargers is the way they are driven. Superchargers are belt driven and create boost (as needed) at all engine speeds. Consequently, low-end torque is greatly improved and throttle response is excellent. Turbochargers, on the other hand, are spun by hot exhaust gas. It’s a free ride, so to speak, because there’s no drive belt and no parasitic load on the engine. But a turbo takes time to spool up. This creates a certain amount of throttle lag and doesn’t produce much extra power until the engine passes 2,500 to 3,000 rpm. Decreasing the size of the turbocharger improves throttle response, but the trade-off is less boost and power at high rpm. That’s why some V6 engines run twin-turbos instead of a single larger turbo. It gives them better throttle response as well as high-end power.

Full of Hot Air?
When air is compressed, it gets hot whether it’s being pumped by a supercharger or turbocharger. Turbos obviously run a lot hotter because they are exhaust driven. Hot air is less dense and doesn’t fill the engine’s cylinders as efficiently as cooler air. One way to overcome this effect is to route the air through an “intercooler” or “aftercooler” after it exits the compressor. This special heat exchanger may be an air-to-air cooler mounted in front of the radiator, or a smaller and more compact air-to-water cooler attached to the cooling system. You’ll find both varieties employed on factory turbocharged and supercharged vehicles.

Increasing boost pressure increases effective compression. This, in turn, increases the risk of detonation with low-octane gasoline. Premium fuel is recommended and, on some engines with high static compression ratios (over 10:1), it may be necessary to reduce the compression ratio to a more blower-friendly level.

Superchargers Explained
The most common type of supercharger is the positive displacement “Roots” style blower. Many aftermarket supercharger kits use an Eaton blower, which is identical to the Eaton blowers used on many factory supercharged cars. Inside the compact blower are two counter-rotating helical rotors with three lobes each. The rotor bearings are lubricated by a self-contained oil supply, so no external oil lines are needed.

There are also centrifugal superchargers that function more like a belt-driven turbocharger. Like a turbo, a centrifugal blower needs to be revved up to produce boost pressure. It also requires an external oil supply line for lubrication. A centrifugal blower is about the size of a large alternator and can be mounted in any location where there is enough space.

Kit Concerns
The term “bolt-on” may be a bit misleading; there’s more to installing a supercharger or turbocharger kit than just bolting on a blower. Increased air flow means the engine will also need more fuel and recalibrated spark timing. The stock fuel injectors on most engines do not have enough extra capacity to handle a big increase in air flow. Most aftermarket supercharger and turbocharger kits include larger replacement injectors or a parallel set of injectors to add more fuel to the engine.

Many kits also include add-on electronics to help the engine management system properly handle the increased air flow. The add-ons may include an “interface” module that goes in the wiring harness between the PCM and engine, or a whole new PCM that has been recalibrated to compensate for the added boost pressure. An interface module essentially tricks the PCM into adding fuel or changing timing advance by modifying the sensor input signals to the PCM.

Most of the supercharger and turbocharger kits that are currently available in the aftermarket are emissions legal and CARB-certified for all 50 states. This is an important consideration for any kind of street performance application. Trying to cobble together a kit of your own using parts and pieces from a variety of different suppliers can be a time-consuming, trial-and-error process – and, when you’re done, there’s no guarantee the engine will meet emissions. That’s why kits are a smart way to go. You get everything you need in one box, and all the dyno tuning and emissions testing has already been done for you.

Cash for Kits
But kits aren’t cheap. Retail prices for complete aftermarket bolt-on supercharger and turbocharger kits typically run in the $3,000 to $5,000 range. They’re a bargain, though, when you consider what it takes in time and effort to duplicate the same thing from scratch. You might be able to get the parts for less from various sources, but you’d still have to fabricate your own brackets and hoses – and spend hours developing the right boost pressure, fuel and ignition curves for a customer’s engine.

That’s okay if you’re building a one-of-a-kind race motor for a customer with deep pockets, but for the kind of customer these kits are designed for, the ready-to-go variety is more affordable. Most kits also come with a warranty on the parts. One supplier we spoke with said they offer a two-year or 100,000-mile guarantee on all the parts in their kit.

What’s In It For You?
Installation of a complete kit typically takes about a day to a day and a half depending on the complexity of the kit and your level of expertise. Some shops that do a lot of kit installations have it down to four or five hours flat.

You should easily make $800 to $1,500 on the parts and labor. Usually, no cutting, drilling or welding is required, but there is a lot of disassembly and rerouting of hoses. Mounting brackets are provided, so all you have to do is follow the instructions and put everything together. If the kit includes a cold-air intake system (or if the customer wants one) you may have to cut an opening to reposition the air intake on some applications.

The only drawback with kits is limited availability. There are a variety of aftermarket supercharger and turbocharger kits available today for the Honda Civic, CRX, del Sol, Prelude and S2000; Acura Integra GSR, LS and Type R; and Mazda Miata, but not much for other makes and models. More are under development, but it’s all a numbers game. If the demand isn’t there, a supplier won’t invest the time and money in a kit that won’t sell.

One of the reasons why Hondas have been so hot in the street performance compact car scene is because they’re easy to modify. Honda owners also seem to be the most performance-minded among import vehicle owners. And, as more and more aftermarket performance products become available for Hondas, it fuels the demand even further.

Cold-Air Systems
Another bolt-on modification that is popular these days is a cold-air intake system. The cold-air intake replaces the stock intake hose and air cleaner box with a large (usually chrome-plated) tube and low-restriction air filter. The modification is done as much for looks as it is for improved breathing.

The better kits will include enough plumbing to locate the air filter in a cool location under or outside the engine compartment. The “shortie” kits that just mount under the hood will suck in heat from the radiator. For maximum performance (and detonation resistance), cool air works much better.

Manifold Mentions
Some supercharger kits include a new manifold to mount the blower. Naturally aspirated engines can also find more horsepower and torque by replacing a stock restrictive manifold with an aftermarket performance manifold. As is the case with turbo and blower kits, availability is mostly limited to a few Honda engines.

The manifolds we’ve seen, which are available with a polished or satin finish, retail for around $160 to $200. The street-legal versions are designed to improve throttle response as well as power across all rpm ranges. The manifolds also include extra bosses for adding nitrous oxide.

Extra Boost
If you have a customer who’s looking for something that will give him a real kick in the seat of the pants when he floors the throttle, a nitrous oxide kit is the way to go. Nitrous oxide systems use laughing gas to add more oxygen to the combustion process. It’s an on-off kind of boost to performance, but one that gives more bang for the buck than almost any other performance add-on.

Professional drag racers use nitrous oxide systems to squeeze incredible amounts of power out of their engines. Movies like The Fast and the Furious also show how street racers use it to give themselves an extra edge.

A simple bolt-on “wet” nitrous oxide system for a four- or six-cylinder engine can easily add 35 to 75 horsepower, depending on how big a shot of nitrous is sprayed into the engine when the throttle is floored. Installation is relatively easy and takes four to six hours, depending on where the bottle and plumbing are mounted and how much drilling and tapping is required to mount the spray nozzle(s).

“Universal” nitrous kits are available with various nozzle calibrations that can be installed on almost any engine. A typical kit includes a 10-lb. nitrous bottle, nozzles, solenoids, wiring and plumbing, and costs $600 to $900. Nitrous costs about $4 per pound and is available from a network of dealers across the country.

The only drawbacks with nitrous are (1) it is not street legal, and (2) it must be used properly otherwise there is a risk of damaging the engine. Some states have actually passed laws making it illegal to have the nitrous bottle connected or the valve on when a vehicle is being driven on the street. Giving an engine a big shot of nitrous also means the engine needs extra fuel, so there’s a danger of leaning out the mixture and burning a piston if the system isn’t calibrated properly.

Did You Know? The aftermarket car parts industry has been growing an average 8% a year during the last 10 years, with 9% growth in 2004, according to the Specialty Equipment Market Association (SEMA).

Did You Know? You don’t have to install an intercooler or aftercooler with a supercharger or turbocharger kit, but doing so allows you to run more boost pressure and make more horsepower (typically 10-15% over a non-intercooled blower or turbo). Intercooling also helps reduce the risk of engine-damaging detonation under high load, which is a major concern with forced induction systems.