Boating World

Trailering: Big Boost

Need more oomph? Know what key parts are needed to ensure your tow vehicle doesn't run out on you.

by Randy Scott

A tow vehicle can do double-duty. When it’s not towing the boat, it can be used to run errands around town. While it may perform admirably for everyday driving, sometimes it’ll labor when a boat and trailer are attached. If you want more “oomph” from your tow vehicle, there are a number of things you can do to increase its performance.

Take A Deep Breath

Like people, engines breathe, and the better they breathe, the better they operate. For instance, an asthmatic generally can’t run as well as a non-asthmatic. The same principle applies to an engine. Fortunately, there are a number of ways to enhance an engine’s breathing to achieve better performance.

An engine’s inhaling and exhaling process is referred to as “intake” and “exhaust.” If an engine has a restricted intake system, it can’t inhale enough air to generate a lot of power. To alleviate the problem, you can install a number of less-restrictive intake components. The most obvious is the air filter, which strains out particles like dirt before they reach the motor. Replacing your standard-issue air filter with a high-flow design can improve air intake by as much as 50 percent in some applications. When purchasing a high-flow air filter, it’s best to invest in one that can be cleaned and reused.

To get the most from your new air filter, however, you should consider purchasing the filter in a kit that includes a larger air box (where the filter is housed) and a larger intake tract that leads from the filter to the engine’s throttle body. Replacing all of these components with higher-flow capacity parts will increase your engine’s horsepower and torque, which is a real asset when towing. In many cases, it also improves fuel efficiency. Be sure, however, that the system you purchase is smog-legal according to the laws of whatever state you live in.

A high-flow air filter can increase a tow rig's intake by 50 percent.

Build Up Breathing

To further improve your tow vehicle’s breathing capacity, you can give attention to the throttle body, which is where the air is directed next. Here, a sensor detects the amount of air headed toward the engine so the vehicle’s computer can react by supplying the appropriate amount of fuel. This way, you’re assured of having a proper air/fuel ratio for optimum combustion. Because your new air filter system is now routing more air up to this point, installing a larger-diameter throttle body will ensure it doesn’t get restricted. Also available are aftermarket throttle body enhancers, which use specially designed spacers to cause the air to spin, so it enters the throttle body at a faster velocity. The “charged” air is said to better atomize the fuel in the combustion chamber for a more efficient burn.

From the throttle body, the air goes through the intake manifold, which is the next area where you can improve your engine’s breathing and performance. High-performance intake manifolds allow for a greater volume of airflow. They’re also designed with less twists and turns than many stock manifolds, which allows for less-restricted airflow. Some intake manifolds even “tune” the airflow so it produces more power at a given engine speed.

Finally, you can also improve your engine’s performance by upgrading standard cylinder heads with units that provide better airflow and better combustion of the air/fuel mixture. Your cylinder heads are where the air mixes with fuel and is ignited. Obviously, cylinder heads that provide a more complete combustion produce more power and less waste. If you have performed the previous airflow steps, upgrading to high-performance cylinder heads will bring all your efforts to fruition. The result is an engine that delivers more power, better performance and improved fuel economy.

You may see performance gains by carrying out any one of the foregoing procedures, but for the greatest benefit, it’s best to do them all. If you do, it’s possible you’ll have so much improved airflow to the engine that the fuel delivery system will need help to keep pace with it. In that case, you may need to replace the factory fuel pump with a high-performance unit. You might also find it beneficial to change to larger fuel injectors that spray more fuel into the engine for optimal air/fuel mix.

Wait To Exhale

After an engine burns the air and fuel mixture in the combustion chamber, the breathing process continues. It now needs to exhale gases resulting from combustion, via the vehicle’s exhaust system. Exhaust gases leaving the cylinder head now enter an exhaust manifold. As with the intake manifold, many exhaust manifolds supplied by the factory restrict airflow unnecessarily, which hampers the engine’s performance potential. This restriction is compounded if airflow has increased through the various intake enhancements described earlier. Switching to an aftermarket exhaust manifold can also increase your engine’s performance, because it facilitates larger volumes of spent gas and even provides them with a smoother exit route.

From the exhaust manifold, exhaust gases are routed through a catalytic converter. Here, a series of internal catalysts convert harmful chemicals — like carbon monoxide, hydrocarbons and nitrogen oxides — into less harmful emissions. Laws prohibit tampering with and replacing properly functioning catalytic converters, so there’s not much you can do here. If it doesn’t work properly (the smell of rotten eggs is a telltale sign), you can replace it with a high-flow design rather than the stock unit provided by the manufacturer.

Having done its job, the catalytic converter sends the exhaust to the muffler(s). As the name implies, this exhaust component muffles the noise as the emissions pass through a series of baffles and sound-deadening materials. While mufflers are designed to prevent back-pressure buildup, by their nature, they somewhat restrict the exhaust flow. Nonetheless, there are many patented high-performance mufflers that use sophisticated sound-abating technologies to increase your vehicle’s power output. Many of them also allow you to select the particular tone or sound desired.

Cat-back exhaust systems provide another alternative. These high-performance systems replace all the components behind the catalytic converter (hence the name “cat-back”) — the exhaust pipe running from the converter to the muffler, the muffler itself, and the tailpipe. Most cat-back systems use larger-diameter pipes designed for better flow and increased performance. The pipes are also usually manufactured from a higher grade of metal to better fight corrosion.

There’s no question about it: A vehicle that breathes better performs better. This is especially true when it has to do extra work, like towing a boat and trailer. If your tow rig has lackluster performance, these tips can help considerably. All the improvements described here can be done in stages, but your best results will come if you begin each process at the initial stage and gradually complete the entire process. In many cases, you’ll not only achieve more power, but you’ll also get better gas mileage.

Installing a cat-back exhaust system improves air flow and overall performance,
and since it's made of a high-grade material, it even prevents corrosion.

Power Booster

Steps to improve your engine’s power through better airflow:

Air Intake
1) Install a high-flow air filter kit.
2) Attach the air filter kit onto a larger-diameter throttle body.
3) Replace stock intake manifolds with non-restrictive, high-flow ones.
4) Swap out the base cylinder heads with a set of high-performance heads.

Exhaust
1) Replace factory exhaust manifolds with high-performance units.
2) When it’s time to replace your catalytic converter, go with a high-flow design.
3) Purchase a high-performance muffler.
4) Consider a complete cat-back system.

Sources

K&N Filters www.knfilters.com
AirAid www.airaidsales.com or autotrucktoys.com
Flowmaster Mufflers www.flowmastermufflers.com
Edelbrock Automotive www.edelbrock.com
Borla Performance Industries www.borla.com