Tech Feature: Power Your Profits with Performance Mods

Tech Feature: Power Your Profits with Performance Mods

The sport compact car market is certainly a good place to be these days. One of the advantages of doing import performance modifications and upgrades is that you don't have to wait for cars to break to get business. The people who drive these cars spend money on performance modifications regardless of the age, mileage or condition of their vehicles.

By Larry Carley
Technical Editor

The sport compact car market is certainly a good place to be these days. One of the advantages of doing import performance modifications and upgrades is that you don’t have to wait for cars to break to get business. The people who drive these cars spend money on performance modifications regardless of the age, mileage or condition of their vehicles.

Another plus is that you don’t have as much competition as you do in the regular repair business if you specialize in performance work. It’s a specialized niche market, and you can often charge top dollar for your labor and expertise.

Performance work can be a very profitable niche, if you have the customer base to support a full-time business. It can be fun, too, especially if you’re into racing yourself, or own a modified sport compact car, truck or SUV.

The reason why more shops are not into this kind of work is that it takes specialized know-how and a completely different mindset than what is usually required to operate a repair shop.

When your focus is on general repair work, you usually don’t see customers until something goes wrong with their vehicle or if it needs maintenance. You make your money by turning as many repair jobs as you can, trying to maximize your labor hours and keep your technicians productive.

With performance work, it’s a different scenario. First of all, your customers may come to you and ask for your opinion about a particular upgrade. They’ve heard about a new aftermarket cylinder head for their Honda and wonder how much you would charge to install it. Or maybe they want a bigger turbocharger on their engine, or a nitrous oxide system, or both, and want to know if their engine can handle it. So the first step in doing performance engine work is often selling the job to the customer. You need to discuss their needs, their hopes and, most importantly, how much they are willing to spend. Then it’s up to you to figure out the best approach to help them achieve their goal, to list the modifications you recommend and to give them an estimate.

In recent years, there has been an explosion of aftermarket performance parts for the sport compact car market, as well as for import trucks, crossover vehicles and SUVs. Pick up any magazine that caters to this audience, and you’ll see page after page of advertisements for bolt-on cold air systems, engine dress-up accessories, exhaust systems, coil-over suspension kits, spoilers, wings, air dams, ground effects body kits, wheels, tires — you name it.

A lot of these products are aimed at the DIY market and don’t require much skill or expertise to install. But there has also been an increase in serious performance parts, too, such as trick aftermarket cylinder heads, engine blocks, camshafts, induction systems, turbocharger and supercharger kits, even complete crate engines for those who are serious about realizing significant performance gains.

Though many of these engine parts were initially designed for a handful of professional racers, the demand for serious engine performance parts for import cars has been growing steadily. Several aftermarket engine remanufacturers are now offering performance crate engines for Honda and Acura, with other applications planned for future release. The volumes are relatively small compared to what’s being sold for domestic V8s, but it’s growing.

Bolt-on goodies such as cold air intake systems, exhaust headers, low-restriction exhaust systems and mufflers all provide some improvement over stock, but they won’t deliver the kind of performance many vehicle owners really want. Adding 20, 30 or 40 additional horsepower doesn’t deliver the same kind of kick in the seat of the pants that adding 100, 200 or 400 horsepower will. That’s where the need for performance experience and installation know-how come into play.

Anybody can order simple bolt-on goodies from a catalog or online. Some DIYers have the tools and wherewithal to rebuild a stock engine, but few have the knowledge, experience or specialized equipment to do serious performance work.

We’re talking things like flow-testing cylinder heads, match-porting an intake manifold to a cylinder head, cc combustion chambers, advancing or retarding a camshaft, modifying the valvetrain for more lift, modifying compression ratios, reprogramming or modifying the fuel and ignition curves in an engine computer, setting up a turbocharger, supercharger or nitrous oxide system so detonation or preignition doesn’t destroy the engine, etc.

These types of jobs require specialized skills, experience and equipment. If your shop has it all, the business can be yours for the asking.

Small engines don’t have a lot of displacement to make power, so they have to breathe efficiently. That’s why many OEM heads have four valves per cylinder. More valve area increases airflow at higher rpm.

Engine modifications that can increase airflow include installing a higher lift, longer duration performance camshaft, enlarging and smoothing the ports in the cylinder head to optimize airflow (which requires using a flow bench), installing larger valves, replacing the stock intake manifold with a larger, higher velocity manifold, or bolting on a forced induction system such as a supercharger or turbocharger.

Computer numeric controlled (CNC) machined heads have become popular in recent years because they are an affordable alternative to hand-porting heads. Once a port profile has been developed on a flow bench for a particular application, it can be mapped and duplicated by a CNC machine. The result is greater consistency and less time-consuming hand-porting work.

Other head modifications may include narrowing the valve guide boss, shortening the amount of guide that protrudes into the port, and installing performance valves that have undercut stems just above the valve head. Removing metal in the combustion chamber to unshroud the valves improves breathing, too, and polishing the chambers can minimize carbon buildup and the risk of detonation.

Additional gains in airflow can also be found by carefully matching and blending the intake and exhaust ports in the cylinder head with the intake and exhaust manifolds.

Another performance trick that’s often recommended is “blueprinting” the engine. This involves measuring and equalizing the volume of the combustion chambers (“ccing” the head) to ensure equal compression and power output cylinder-to-cylinder.

Valve lift, duration and seat angles also play a big role in airflow. The combustion chambers in most Asian vehicle 4-valve heads are pretty cramped so there’s not a lot of room to make changes. Even so, blending the bowl area to the seats and ports can improve airflow, as can using a 3- or 5-angle cut on the valves and seats.

To achieve higher rpm, stiffer valve springs are a must along with lightweight titanium retainers. Titanium valves can also reduce valvetrain weight, but are very expensive for a street engine. But if a customer has deep pockets and wants the best, why not?

Installing a turbocharger or supercharger on a naturally aspirated engine can often add 50% or more power. Likewise, replacing a factory turbocharger with a larger aftermarket turbo can add considerable power to any engine. Power output becomes a matter of how much boost the engine can safely handle. It’s not unusual to see street turbocharged Hondas putting out upward of 400 to 500 horsepower these days. A few are even making 800-plus horsepower!

Installing aftermarket turbo kits on a customer’s car typically takes about two to three days with a well-engineered kit. Many of these kits retail in the $3,500 to $5,000 range, and include all the plumbing and parts needed to make the changeover. Some even include larger flow fuel injectors and a computer module.

As power goes up, reliability goes down. Force-feeding an otherwise stock engine with a blower or turbo, or boosting power with a shot of nitrous, increases combustion temperatures and pressures to the point where detonation and preignition become a serious concern. If there’s too much spark advance or the fuel mixture goes lean at high rpm, your customer will probably fry a piston. The stock head gasket may also be unable to contain the additional pressure, and may have to be replaced with a high-performance gasket or copper head gasket.

Higher combustion pressures also increase the load on the pistons, connecting rods, crankshafts, bearings and block. Stronger forged or hypereutectic pistons may have to be substituted for stock cast pistons. Stronger chrome moly steel rods may have to be substituted for stock cast iron rods. Bearing clearances may have to be changed to improve oil pressure and lubrication. The crankshaft may have to be balanced and polished for higher rpm durability. If the engine has been fitted with a stroker crank to increase displacement and torque, there will be more load on the crank throws. Consequently, the journal fillets may have to be enlarged to reduce stress and the risk of breakage.

In addition to the engine, the rest of the drivetrain will have to be beefed up to handle the greater power output. The stock clutch will have to be replaced with a higher capacity clutch, and the disc with one that is faced with ceramic, metallic or carbon facings to handle the heat.

The cooling capacity of the cooling system may also have to be upgraded by installing a larger or thicker radiator, and/or a larger or additional cooling fan to handle the heat. An add-on oil cooler for the engine oil isn’t a bad idea, as is a larger or more efficient cooler for the transmission.

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