Performance Upgrades: Tuning, Tweaking & Boosting Your Way to New Profits

Performance Upgrades: Tuning, Tweaking & Boosting Your Way to New Profits

The import performance market offers a unique service opportunity for you. Import vehicle owners are accessorizing their vehicles like never before, and many are buying aftermarket performance parts in record numbers. Though many of these parts are sold to people who can install the parts themselves (things like wings, spoilers, lights, big bore mufflers, etc.), some parts require a much higher level of expertise to install, as well as special tools and equipment that the typical DIYer doesn’t have.

We’re talking serious performance parts such as camshafts and cylinder heads, stroker cranks and engine kits, and turbocharger and supercharger kits. Some DIYers may be able to install their own struts, coil-overs, springs and other chassis components, but it’s very unlikely they’ll have any means of realigning the suspension once their vehicle has been modified. As a result, there is a growing demand for import specialists who can do this kind of performance work for their customers.

The best thing about performance work is that customers actually “want” (rather than need) to spend money on their vehicles. They’ll gladly pay you to remove perfectly good parts from their vehicles so aftermarket performance parts can be installed in their place. With performance work, there’s no waiting until the vehicle is out of warranty to get the customer’s business. And there’s no waiting six, eight or even 10 or more years for the original parts to wear out. The work is available right now for those who are willing to do it.

Performance work, however, requires a somewhat different attitude and approach than ordinary repair work. For one thing, you’re not racing the clock to beat flat rate. You’re billing the customer for the actual labor time that goes into the job – which can sometimes be rather lengthy depending on the type of parts you’re installing. Hanging a turbocharger on a naturally aspirated engine can easily be an all-day undertaking that may even stretch into a couple of days, depending on how well the kit is designed for the application and how much modification work is needed to make it fit. Once you’ve done more of this kind of work, you’ll have a better idea of how much time it usually takes and how to price it.

The customer’s attitude is also different. The typical performance customer is anxious to spend money and is anticipating a lot of bang for his buck. The typical repair customer, on the other hand, is reluctant to spend money and usually complains about every nickel and dime he’s asked to spend on repairs or maintenance. You want to make both types of customers happy, obviously, but it’s easier with the performance customer because you’re giving him something he didn’t have before. With a repair customer, you’re only fixing his problem.

Another nice thing about doing performance work is that you usually own your customers from that point on, once you’ve worked on their vehicle. Why? Because you’re the one who installed the parts, so you’re the one they’re going to come back to every time they want to make more modifications – or when they break something (which tends to happen quite often with these types of vehicles).

You usually don’t have to worry about a competitor stealing your customer because you probably won’t have much competition. Performance work is usually done by specialists, not the retailers, chain stores, new car dealers or general repair garages, who are all competing against you for repair and maintenance work.

Less competition means you can charge more for your labor and earn a better return on your time. Margins on aftermarket performance parts also tend to be more generous than those you typically get from traditional components. So it all adds up to a profitable niche that can grow your business and expand your customer base.

Serious engine modifications have always required a high level of expertise, combined with racing experience. But this kind of work is getting easier thanks to the increased availability of aftermarket cylinder heads, blocks, stroker cranks, performance engine kits and even complete preassembled, ready-to-install crate engines.

Installing an aftermarket performance cam is a fairly straightforward swap for the stock cam, but may also require replacing the stock valve springs with stronger springs. As a rule, the original valve springs should not be reused because they lose tension with age. The higher the mileage on the springs, the less tension they’ll exert against the valves. For an ordinary stock engine, this may not be an issue. But for a high-revving performance engine, strong valve springs are an absolute must to maximize the engine’s rpm potential and to minimize the risk of valve float or a valve hitting a piston.

Since most import engines have overhead cams, you don’t have to worry much about the changes in valvetrain geometry that typically require changing pushrod lengths in pushrod engines. In most cases, all you have to do is replace the stock cam(s), install a new timing belt or chain (highly recommended for reliability), line up the timing marks and button up the engine.

Most street cams have several degrees of advance built in to improve low-speed torque (advancing cam timing improves low rpm power, while retarding cam timing boosts top-end power). Depending on the application, though, you may want to “degree” the cam and advance or retard the timing a few degrees one way or the other to move the engine’s torque curve up or down the rpm scale.

If you’re overhauling an engine, chances are the block will require minimal machine work. The hard alloy blocks that are typically used in many Japanese engines usually show little cylinder wear even at high mileage. Even so, if the cylinders show taper wear or are damaged, the block will have to be bored to oversize.

Increasing the bore size adds displacement (which is good for more power) but it also increases compression. In a naturally aspirated engine, a half a percentage point increase in compression is usually no big deal. But in a turbocharged or supercharged engine, it increases the risk of engine-damaging detonation. It may, therefore, be necessary to compensate for the increased bore size by shaving the tops of the pistons, or using a thicker head gasket to offset the increase in compression. Changing the installed height of an OHC cylinder head, though, affects valve timing, so that may require additional changes in cam timing. See how one modification usually affects something else? That’s why you have to know what you’re doing when you start making performance modifications to an engine.

The bottom end of most import engines is fairly strong, so other than turning the crank and/or installing a new set of bearings, the bottom end probably needs little else done to it. The stock crank in many of these engines is forged, and the stock rods and pistons are more than adequate to handle a hotter cam and induction system.

If your customer has a couple of thousand bucks to spend and wants a significant increase in both torque and power, you can replace the stock crankshaft with an aftermarket stroker crank. Stroker cranks are available for many of the more popular engines, and are usually sold as complete kits that include new pistons, rings, connecting rods and bearings. A stroker crank delivers a lot of bang for the buck. A 5 mm stroker crank that increases stroke from 89 mm to 94 mm in a 2,400 cc engine will increase the engine’s displacement approximately 440 cc. The extra displacement alone is typically good for up to a 30% increase in torque throughout the rpm range, and 40 to 50 more horsepower in an otherwise stock engine. These kinds of numbers mean more off-the-line power, faster acceleration (especially at lower rpm) and better driveability (especially with longer-duration camshafts).

Another area where significant horsepower gains can be found is in the cylinder head. Stock heads are typically engineered to deliver a good compromise between torque, driveability, emissions and power. Smaller port sizes increase air velocity, which is good for low rpm power, emissions and driveability, but limits the head’s ability to breathe and make power at high rpm. Larger ports and valves increase airflow and the potential to make power, but may sacrifice low-speed torque and driveability.

So what kind of head configuration works best on a given engine application will depend on the engine’s displacement, power range, gearing and how the vehicle will be used (street or racing). An all-out 800-hp, turbocharged racing engine may run great on the drag strip but would probably not be a very driveable street engine.

Until recently, reworking cylinder heads required considerable expertise and experience. Anybody with a die grinder can rework an aluminum cylinder head. But hogging out the ports without any understanding of how it changes airflow can often do more harm than good. Porting requires a lot of development time on a flow bench as well as the race track. Big flow numbers alone aren’t necessarily the goal to aim for if the modified ports end up creating unwanted turbulence in the combustion chambers that causes the air/fuel mixture to separate. That’s why head porting is best left to people who know what they’re doing.

One of the biggest advances in head porting in recent years has been computer-controlled numeric (CNC) machining. Once a winning head port configuration has been developed, it can be digitally mapped and duplicated by CNC equipment over and over again on stock or aftermarket castings. CNC machining is a much faster and more accurate method of porting heads than hand grinding. It’s also cheaper because it takes minimal labor. Even so, it can still cost hundreds of dollars to CNC machine a head because of the expensive high-tech equipment that’s required and the R&D development work that has gone into it.

The easiest way to pick up horsepower in the cylinder head is to replace the stock head with an aftermarket performance head. Aftermarket heads take the guesswork out of making modifications, and are essentially bolt-on installations. The ports are cast or CNC machined with an optimal profile, and the heads typically have oversized valves with a multi-angle valve job to enhance breathing. The head may also feature better materials in the seats and guides, and come preassembled with performance springs and valve retainers.

If you don’t want to overhaul engines or replace heads in your shop, another alternative is to simply swap the stock engine for a performance crate engine. Several companies now offer preassembled Honda and Mitsubishi crate engines that are built to give your customer 270 to 300 horsepower right out of the box. Crate engines like these typically retail for $10,000 to $12,000 and come with a 12-month, 12,000-mile warranty.

The popularity of crate engines has really grown in recent years for a number of reasons. There’s no guesswork in choosing parts because the parts that go into a crate engine are properly matched and chosen to deliver a certain level of performance. There’s no waiting for custom machine work or searching for a machine shop with the skill to do this kind of work. Most crate engines are sold outright, so there are no exchange hassles (plus the old engine can be sold to someone else if it’s still good). And there’s no risk of misassembly because the engine comes assembled, pre-tested and ready-to-install. All you have to do install the intake plumbing, ignition system and exhaust, and do the final tuning.

The most difficult aspect of modifying late-model computer-controlled engines has always been tuning. Any changes that affect compression, the air/fuel mixture or airflow through the engine (such as increasing boost pressure, changing the cam or cylinder head, or even modifying the exhaust system) affects how the computer controls fuel delivery and ignition timing. The oxygen sensor and feedback fuel control loop can compensate to some extent for modifications that affect the air/fuel mixture, but not spark timing. The engine’s knock sensor will retard timing if it detects vibrations that tell it the engine is experiencing detonation, but it may not be enough or may have an adverse effect on performance.

Recalibrating a powertrain control module (PCM) isn’t easy because it takes special software and a scan tool to hack into the PCM so you can alter the stock fuel mixture and timing settings. On some older vehicles, the PCM can be tweaked to boost performance by replacing the stock Program Read Only Memory (PROM) chip with an aftermarket chip (or installing a special “piggyback module” between the stock PCM and the engine) that allows a slightly richer air/fuel mixture and/or more spark advance under certain operating conditions. On newer vehicles, Electronically Erasable Read Only Memory (EEPROM) chips are used to allow the PCM to be easily reprogrammed with new instructions.

Several aftermarket companies now sell special “tuner” scan tools that almost anyone can use to change a vehicle’s PCM settings for more performance. These tools can be used to disable the rpm and speed limiter, increase boost pressure on a turbocharged engine, change the air/fuel mixture and spark timing, recalibrate the speedometer for changes in gearing or tire/wheel sizes, change the shift points of an automatic transmission, and download and install custom tuning programs from the internet that various people have developed for specific engine applications and modifications. Some of these tools can also read DTCs, and even capture and reset the PCM back to its original stock settings, if there is a reason to do so at a later date.

The new generation of tuner scan tools make it much easier to play around with the PCM settings – and also to screw things up if you don’t know what you’re doing. Too much spark advance increases the risk of engine-damaging detonation and pre-ignition. Raising or disabling the rev limiter increases the risk of valve float and damage if the stock valvetrain can’t handle the increased rpm. Raising or disabling the speed limiter with no consideration for the speed rating of the tires is asking for trouble. As with any other kind of performance modification, changing the PCM settings takes know-how and experience.

What goes in has to come out, so any engine that’s being modified to make more power needs a less-restrictive exhaust system. Replacing the stock muffler with some type of performance muffler is always good for a few extra horsepower. Install a whole new free-flowing exhaust system, and you’ll pick up even more power. Ceramic/metallic coated headers cost more than plain headers but more than pay for themselves by providing years of rust-free durability on street-driven vehicles.

Replacing a clutch on a front-wheel-drive car is not a job most do-it-yourselfers are willing or even able to undertake. It can be done in a garage or backyard, but it’s a lot easier in a service bay with a lift, engine support and proper tools. Replacing the clutch is something that will be necessary sooner or later if the engine has been modified to make more power. The combination of increased power and aggressive driving will demand a stronger clutch.

An aftermarket performance clutch can provide both increased pressure (less slip) and better durability than a stock clutch. On many applications, you can install a larger diameter clutch to increase the surface area of the clutch disc. You can also use a clutch disc with better friction materials such as ceramic/metallic that offer improved heat and wear resistance.

As for suspension modifications, it depends on what kind of handling performance your customer wants. A lower, stiffer suspension means better handling and cornering on smooth pavement, but also a rougher ride when the road isn’t so smooth. The stock suspensions on most sport compacts aren’t bad, but there’s always room for improvement.

Replacing the stock shocks/struts with aftermarket monotube or twin-tube gas dampers can reduce shock lag and fade. Adjustable shocks/struts are a good choice for vehicles that may be raced on the weekend but used for daily transportation the rest of the week. A complete suspension package that includes performance shocks/struts and springs (or coilovers), plus a stiffer sway bar and suspension bushings, will usually provide the best results.

You May Also Like

The Do’s and Don’ts of Installing Spark Plugs

This article discusses the “conscious” steps you should perform during spark plug replacement.

Spark plug replacement is often considered one of the least complicated tasks at a shop. But, ignorance of what you are dealing with can get you into trouble before, during and after the new plugs are installed.

Blindly removing and replacing components without inspection can cause your shop to fall into a diagnostic black hole trying to find the cause of a misfire that was not there before.

Beyond the Warranty

What does it take to keep a car going for 120,000, 180,000 or 250,000 miles? The key is maintenance and inspection. 

Misfire Codes P0300, P0301-P0312 and P0313+P0314

The only way to clear the code is to use a crankshaft position relearn with a scan tool.

What Caused The Turbo To Fail?

Up to 50% of turbocharger failures are due to oiling problems.

Valve Lifter Technology

Hydraulic lifters are precision-fit assemblies.

Other Posts
Auxiliary Water Pump Diagnostics

A car or truck comes into your shop with a complaint of poor heater performance- the issue may be the auxiliary water pump.

Supercharger Pros And Cons

Customers generally look to superchargers for the instant throttle response, not fuel economy.

It’s Got Spark!

Why can’t you trust some spark tests?

Belts and Pulley Alignment

A misalignment of the plane of the belt can occur when a pulley is not parallel to the other pulleys on the belt drive system.