Even though your sport utility's engine currently sends plenty of power to the wheels, there are always ways of getting more juice out of the powerplant. There are many methods that can be used to accomplish this, some more obvious than others. Many of the best-known methods involve increasing the airflow, fuel flow, and removal of spent gases. While the list of products that add extra pulling power can be fairly easy to name, it's the others that require a little more digging. Sometimes making the engine perform more efficiently can be the best way to improve throttle response and acceleration. This guide covers both aspects of improving performance in your sport utility. We picked 20 of our favorite bolt-on performance items to show you. The guide will show a little of what is involved in the installation, and explain what the components generally do to make the engine perform. At the end of the story are sources for more information about these items.
Air Induction
With any engine modification, improving airflow or fuel flow into the engine, or improving the flow of exhaust gases out of the engine, will result in increased power. Air induction kits, also known as air intakes, were designed to provide optimal airflow. Each system uses a tube that provides reduced restriction to the flow of air, which increases the amount of air that can be brought into the engine. These kits use a two-pronged approach to increasing airflow: They straighten out the path the air takes, and they have a filter made to provide more surface area for the air to flow through. Another method that is used in some air induction kits is the use of cold air. The theory behind cold-air intakes is that cold air is more dense with oxygen than warm air, meaning that you can actually get more oxygen in a given amount of space if it is at a cooler temperature. When the SUV's computer senses the increased air, it adds more fuel and spark to accommodate it, thus creating more power.
Spark Plugs and Spark Plug Wires
Plug wires can make an ignition system work to its full potential. Installing a new set of spark plugs and plug wires won't give the vehicle more horsepower and torque, but it will improve the way your ignition system functions, and therefore will make the engine run better. By replacing these items with aftermarket plugs and wires, the ignition's spark will be made more consistent, and will help ensure the ignition of the air/fuel mixture every time. Also, high-quality spark plugs will remove heat from the combustion chamber while remaining resistant to heat. Some plugs have been designed to create a larger spark as well. When it comes to spark plug wires, a good set will be built with the durability to resist wear from heat and will provide low resistance for the best possible transfer from the plugs.
Throttle Body - Throttle Body Spacer
Throttle bodies also work to bring air into the engine, and installing a larger throttle body will bring more air in. Adding a throttle body spacer to the mix doesn't increase airflow, but allows the engine to make better use of the air that's being brought in. The AIRAID throttle body spacer shown here has a design that causes the incoming air to spin. The spinning action continues into the combustion chamber, which affects the air/fuel mixture itself. These items can increase airflow by 25 percent or more, depending on the vehicle, and can improve power by 5 to 10 hp.
Replacement Air Filters
It's likely that the air filter that came with your sport utility is made of paper, and you'll need to replace it within a couple of years. Air filters made of paper are not the best material for filtration, and will not last very long. Vehicle manufacturers like them because they are affordable and there are thousands of applications they work with. A good, easy way to add power is by replacing this filter with a reusable filter. These filters have multiple-layer elements with more pleats than the OE filter, meaning there is more surface area to improve airflow. Some filters also have an extra layer of oil or synthetic material to filter smaller particulates. These filters can be good for as long as 50,000 miles, can improve fuel economy by 10 percent, and can provide as much as a 15hp increase, depending on the vehicle.
Catalytic Converter
Removing spent exhaust gases from the engine is only part of what your SUV's exhaust system does. Another role it plays is that of emissions reducer -- the catalytic converter, in particular, exists to make sure that fewer harmful emissions pollute the air. It does this by converting the toxins into safe emissions. Over time, the converter can become clogged, and not only does it function poorly, but the entire exhaust system can be compromised as well. When a catalytic converter wears out, replacing it with an aftermarket catalytic converter can get the exhaust as good as or in some cases, better than new. Many aftermarket catalytic converters have a higher flow rate than stock, so the replacement can provide even more power. Some states do not allow you to replace your catalytic converter until it is worn out or has significant mileage on it. As we would recommend with all of the modifications in this story, make sure installing these components on your SUV is legal in your state.
Exhaust System
On the other side of the engine, the exhaust system is designed to get spent exhaust gases out of the engine, and out of the vehicle. Aftermarket exhausts are made to provide the quickest route for the gases, with the fewest restrictions possible. Improving flow on this side of the process means that air/fuel combustion can be done more quickly and efficiently. Once spent gases are out of the way, there is room for new air and fuel to come in. In addition, OE mufflers are made to reduce sound, and the components used to do this can cause a loss of performance. After-cat exhausts can improve performance by 10 hp and much, much more, depending on the system you choose.
Fuel Pump
Installing a better-designed or higher-pressure fuel pump can increase the flow of fuel to your engine. Even though more flow can be advantageous, when choosing a new fuel pump it is important to select one that provides the right flow for your needs. A race-ready pump, while it provides incredible flow and pressure, would most likely be too much pump for your sport utility. A new fuel pump is almost a necessity after a new supercharger has been installed, and many supercharger systems include a new pump. There are two types of fuel pumps, in-tank and inline, that are either electric or mechanical designs. The inline pumps can be installed in more locations on the vehicle than the in-tank design but are farther from the source of fuel. Mechanical pumps are found mostly on older vehicles, and electric pumps are the common type for newer SUVs.
Ignition Upgrades
A new ignition system can help improve throttle response, power, and fuel economy, and can smooth out your SUV's idle. Aftermarket ignition systems, especially multiple-sparking units, provide more spark than standard ignition systems under a specific rpm, and emit a single spark above that rpm. These sparks also last longer. The combination of the two means more of the air/fuel mixture will be burned, providing more power to the engine and reducing the amount of wasted materials. The ignition system can make the engine operate much more efficiently. There are many types of aftermarket ignitions that can make a difference on your vehicle; the trick is finding the right one for you. There are some that are ideal for towing, off-road, and heavy-duty applications, some specifically for supercharged engines, and others for normal daily driving. Other things you can do to improve the ignition system include replacing the distributor (if your SUV is so equipped) and adding a rev control system, which can save your engine from damage if the driveline fails.
Engine Programmer/Chips
The theory behind modifying the vehicle's computer is that an aftermarket chip will customize the air/fuel ratio, ignition advance, and transmission shift points to fit your SUV's needs. For stock vehicles, it can optimize these functions, and for modified vehicles, it will change the ratio, ignition advance, and shift points to best match the needs of the new components. While you can purchase a programmer or chip and a thermostat separately, it is recommended that you install both at the same time, and some power packages come with a new thermostat. According to the manufacturers, these computer modifiers can increase power by as much as 30 hp.
Thermostat
Replacing your SUV's thermostat with a lower-temperature model causes the engine's fan to come on sooner than it does with the OE thermostat. This reduced engine temperature can cause the motor to operate more efficiently. The only people who should think twice about replacing their vehicle's thermostats with low-temperature units are those who live in cold climates, where heat is necessary to counter the cold weather. Choosing the right thermostat is not simply a matter of picking the lowest-temperature unit. Engines do like some heat, and if you choose one that causes the fan to come on at too low a temperature, it will start to have less of an effect on the overall cooling of the engine.
MAF Sensors
Mass airflow sensore (MAF) directly airflow, via the sensing element in the air intake. By measuring the airflow at the source, it knows exactly how much air is going into the engine, and can react quickly to changes in flow. As it notes changes in airflow, it sends a signal to ensure the proper fuel and sparl are added to the air to keep the mix correct. Because the mixture is much more accurate and changes with the situation, performance can be improved by 10 hp to 15 hp.
Headers
When you bought your sport utility from the dealer, it came with exhaust manifolds, two for V-configured engines and one for inlines. These manifolds remove exhaust gases from each cylinder, but are not necessarily the most efficient parts to do the job. Headers, which replace the stock exhaust manifolds, efficiently pull, or scavenge the exhaust gases and draw in the next fuel charge. By doing this, headers reduce the pressure that is caused by gas buildup, and make sure that the air/fuel mix is clean. Headers can increase horsepower by 35 and torque by 75 lb-ft, and can improve fuel economy. There are several styles and protective coatings available, and different headers will improve your SUV's power at different points in the rpm range.
Fuel Injectors
Again, flow is a very important part of improving the performance of your sport utility. Increasing the capability of the fuel system to provide fuel for the mix makes it easier to add more air and spark for more power. Aftermarket injectors do just that. If you add a component that increases the volume or pressure of air that enters the combustion chamber, aftermarket injectors can ensure that the fuel side of the combination will be there and will provide the fuel that is needed. Larger injectors are especially worthwhile if your SUV has a supercharger or other high-performance modifications.
Intake Manifold
When you begin to look at making modifications to the key components of the engine to improve power, it is important to look at the entire engine for these improvements. For example, replacing the cam can make a difference in power, but there will be more horsepower and torque if you also replace the intake manifold. Just as replacing exhaust manifolds with headers means a more efficient method of moving gases, replacing OE intake manifolds with aftermarket items means better airflow into the engine. Good aftermarket intake manifolds are application specific and are built to provide the best amount of air in for that application. This is done by reducing restrictions and by making the design of the manifold best fit the design of that specific engine.
Pulleys
There are many reasons why replacing your engine's pulleys can improve the motor's power. If the new pulleys are made from durable materials, they will last longer than the originals, providing less belt slippage and improved contact with the serpentine belt. Smaller pulleys can increase engine cooling by speeding up both water flow and engine fan speed. Using smaller pulleys can also mean a significant increase in power. This change slows the serpentine's belt speed by 25 percent, causing fuel efficiency to increase, and power to go up by 8 to 10 hp. All pulleys, except the alternator pulley, are commonly replaced.
Electric Fan
An electric fan is a more efficient design than the standard pulley-driven fan. Electric fans are made to work more precisely with the engine's needs, turning on and off when the situation calls for it. While the engine fan is more necessary during idle and in heavy traffic, and less necessary on the open highway, the stock fan is less capable of accurately working with changing driving circumstances. Electric fans can also pull in much more air than standard fans. This type of fan can increase horsepower and torque and can make tow vehicles perform better.
Nitrous
Nitrous oxide systems started out as an added boost used in racing but have since been translated to street performance applications. Nitrous systems inject additional air and cool the air that enters the combustion chamber. This process adds as much as 150 hp in an instant, but it is only meant to be used for brief amounts of time. It is a power upgrade that can make getting on the freeway a lot of fun, but it isn't something that will give your SUV long-term improved performance or efficiency. This is a modification that is safe when done at a trustworthy shop by knowledgeable technicians but can be dangerous without the proper safety precautions.
Engine Work
When it gets right down to it, the most complex (and one of the most effective) ways to get more power out of your engine is by optimizing the engine's design. Replacing the cam and the cylinder heads can make the engine dramatically more efficient and can cause the creation of more power from the air/fuel mixture. Four-stroke engines use exhaust and intake valves. The exhaust valves remove spent gases, making room for new air and fuel. The intake valves bring in the next charge. When the camshaft rotates, it causes the valves to open and close, and the timing of this process can make the most out of the air/fuel mixture that powers your SUV. Replacing the cam can mean improved high-rpm performance for better low-rpm performance, depending on the unit you choose. New cylinder heads can mean an increase in the amount of air coming in to the engine, increasing power.
High-Output Alternator
A high-output alternator will make your entire engine run better by providing the right power to make the electrical system work properly. With many SUVs in today's world, there are entertainment features and electronics goodies installed on-board to keep passengers happy while on the road. Unfortunately, these devices can put a load on the engine, and if the alternator is not a high-output model, it probably can't take the load. If you've sat at a red light and noticed your headlights dimmed when you lowered the power windows, your alternator is not providing enough juice to the system. Adding extra batteries has been the common solution to the power problem, but the truth is the alternator is the device that powers your mobile electronics system, off-road lights, and electric fan. If your alternator can't handle the demand, the power can be drawn from the battery. High-output alternators can do a better job of powering these accessories and are built to withstand the heat created by your vehicle's engine.
Superchargers
The biggest, most readily noticeable modification you can do to give your SUV more power is to have a supercharger installed. A supercharger can safely increase power by 75 to 100 hp, while dramatically improving torque. While there are several different supercharger designs, they generally push pressurized air into the combustion chamber, essentially putting a lot more air in the same amount of space. Some add that air straight into the chamber, while others force the added breathing in before the throttle body. As the technology advances, and more automakers become comfortable with the long-term reliability of superchargers, they will become more and more available from the showroom. In fact, while some vehicles come from the factory with superchargers, there is a growing trend of the option of superchargers as dealer-added items, which fall under the vehicle's original warranty. A supercharger installation is a worthwhile all-day process, not recommended for the novice do-it-yourselfer.*
Here are some good sources for the components in this story. There are many other sources, but this is a sampling of some of the companies you can contact.
Advanced Engine Management (AEM)
Dept. TSUV
2205 126th St., Ste. A
Hawthorne, CA 90250
(310) 484-2322
www.aempower.com
Air filter and intake
AIRAID/Poweraid
Dept. TSUV
14840 N. 74th St.
Scottsdale, AZ 85260
(800) 498-6951
www.airaid.com
Air filter and throttle body spacer
Car Sound Exhaust
Dept. TSUV
22961 Arroyo Vista
Rancho Santa Margarita, CA 92688
(800) 824-8664
www.car-sound.com
Catalytic converter and exhaust
Competition Cams Inc.
Dept. TSUV
3406 Democrat Rd.
Memphis, TN 38118
(800) 365-9145
www.compcams.com
Camshaft
Dealers Sport Truck
Dept. TSUV
3938 Cerritos Ave.
Los Alamitos, CA 90720
(562) 936-1230
www.dealersportruck.com
SUV components
Edelbrock Corp.
Dept. TSUV
2700 California St.
Torrance, CA 90503
(310) 781-2222
www.edelbrock.com
Intake manifold
Flex-a-lite
Dept. TSUV
P.O. Box 580
Milton, WA 98354
(800) 851-1510
www.flex-a-lite.com
Electric fan
Granatelli Motorsports Inc.
Dept. TSUV
1000 Yarnell Pl.
Oxnard, CA 93033
(805) 486-6644
www.granatellimotorsports.com
MAF sensor
Holley Performance Products
Dept. TSUV
1801 Russellville Rd.
Bowling Green, KY 42101
(270) 782-2900
www.holley.com
Fuel injectors and fuel pump
Hypertech Inc.
Dept. TSUV
3215 Appling Rd.
Bartlett, TN 38133
(901) 382-8888
www.hypertech-inc.com
Engine programmer and thermostat
JBA Headers
Dept. TSUV
7149 Mission Gorge Rd., Ste. D
San Diego, CA 92120
(619) 229-7797
www.jbaheaders.com
Exhaust, headers, and spark plug wires
K&N Engineering Inc.
Dept. TSUV
1455 Citrus Ave.
Riverside, CA 92507
(800) 858-3333
www.knfilters.com
Air intake and replacement air filter
MAC Products
Dept. TSUV
43214 Blackdeer Loop
Temecula, CA 92590
(800) 367-4486
www.macperformance.com
Air intake and exhaust
March Performance
Dept. TSUV
6020 Hix Rd.
Westland, MI 48185
(734) 729-9070
www.marchperf.com
Pulleys
MSD Ignition
Dept. TSUV
1490 Henry Brennan Dr.
El Paso, TX 79936
(915) 857-5200
www.msdignition.com
Ignition
NitrousWorks
Dept. TSUV
1450 McDonald Rd.
Dahlonega, GA 30533
(706) 864-7009
www.barrygrant.com
Nitrous oxide system
Paxton
Dept. TSUV
1650 Pacific Ave.
Channel Islands, CA 93033
(888) 9-PAXTON (972-9866)
www.paxtonauto.com
Supercharger
Powermaster
Dept. TSUV
2401 Dutch Valley Rd.
Knoxville, TN 37918
(865) 688-5953
www.powermastermotorsports.com
Alternator