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More Horsepower. Less Fuel.

®

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   Charge Air Cooler

 

A VERY IMPORTANT COMPONENT TO OVERALL ENGINE EFFICIENCY

The charge-air cooler and turbocharger are part of a high tech induction system that increases engine combustion efficiency. The turbocharger uses exhaust gases to compress air before it enters the charge-air cooler.

 

The compressed air going through the charge-air cooler is then cooled by the ambient air flowing across the cooler fins. The cooled air is more dense than warm air. So when it flows into the intake side of the engine, the increased density improves horsepower, fuel economy and reduces emissions. The following illustration provides a clear view of the components associated with the charge-air-cooler and how the air flows through the system:

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Leaks in Your Charge-Air-Cooler Can be Costly

 

Charge-air coolers can develop leaks and can fail if not caught soon enough. A leaking charge-air-cooler can cause the engine to lose up to ½ mpg in fuel economy. To maintain engine power and engine and fuel efficiency, it is important to properly test all charge-air coolers periodically.

 

Causes that contribute to failures (in order of probability) are:

 

           - Heat stress (most common)

           - Vehicle vibration

           - Turbocharger failure

           - Accidents

           - Improper testing methods

 

Charge-Air Cooler Construction

 

Charge-Air-Coolers come in many different sizes and configurations depending on the vehicle application they are used. No matter what    application, the basic components of the unit are the same. These components consist of:

 

        - Inlet and Outlet tanks, or manifolds as they are sometimes called

        - The main core consisting of the internal fins, external fins, and tubes

        - The header plate that is welded to the core and used to attach the tanks

        - The brackets that are used to secure the charge-air-cooler to the vehicle

        - Finally, the top and bottom plates

 

Please refer to the diagram below to see how these components are combined to produce the complete charge-air-cooler.

 

Although same model coolers may look the same, there can be many differences in the quality of the materials used, the brazing processes to attach each component, and the type of core construction used. We will discuss these differences in detail in the next section.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

      Choosing the Best Core

 

Although cores look alike to the average eye, there are vast differences that have a tremendous impact on overall performance and durability. The three main areas of the construction are:

 

            - Overall design of the core

            -Brazing process used in tube to header construction

            - Quality and strength of the materials used to build the core and header plates

 

Tube Design:

There are two types of tube designs – extruded tube and the folded/weld seam design. The walls of the tube should be thicker to withstand burning out from excessive heat, especially the top and bottom tubes. In addition, the thicker walls will protect the tube better against corrosion. Due to the fact of having no potential seam failure and the ability to use higher quality alloys in the production stage, we find the extruded tubes to be stronger and more efficient.

 

The inner fins of the tube are critical to air flow and cooling. The number of fins per inch, position and spacing of these fins will determine the most efficient flow of air through the cooler.

 

 

Brazing Process:

How well the tubes are brazed (joined) to the header plate will affect air leakage, and impact overall performance of the unit. Some manufacturers will use a temporary red sealant called RTV to seal leaks that are caused in the brazing process. This sealant will usually break down in time due to heat conditions. When this occurs, tube to header leaks will begin. An example of this method is shown at the right.

 

Materials:

Fleets are ordering trucks with higher horsepower engines. As the horsepower goes up, the charge-air-coolers are forced to take higher heat loads. However, the OEM coolers being put on the higher horsepower trucks were designed for those with much lower horsepower. The quality and strength of the materials used to produce the core are critical in the core’s ability to stand up against these increased pressures and operating temperatures generated by those engines. The header plate may crack when lightweight materials are used, top and bottom tubes with thin walls may burn out from excessive heat. In addition, thin walled tubes are much more susceptible to damage from corrosion.

 

Picture A is that of a standard OEM core. Picture B shows a heavier duty core that we use for our Turbo-Max coolers. If you look at the header plate and the tube walls, you will see a noticeable difference in the materials used.

 

A

B

 

 

 

   The Final Test

 

We recently had some tests performed on the cores we use versus others. We wanted to test the cores to see how much pressure they took before failure. Here are the results:

 

Standard OEM Core A

 

We are showing you three pictures of the test on this core because it shows failures in three critical areas:

 

   There are only two types of tanks used in CAC construction.

 

          1. Permanent Mold Tanks - Excellent                               2. Sand Cast Tanks - Inferior

 

Some of our competitors will take a new core and use the Sand Cast tank to sell the complete unit as new. In our effort to provide the highest quality products, Fleet Air uses only Permanent Mold tanks. To show you why we use Permanent Mold tanks, the differences in tank construction are shown below:

 

1. Permanent Mold Tanks – these are made from a permanent steel mold and are usually built for and owned by the specific OEM truck manufacturer.

 

Characteristics

 

The combination of the permanent mold and using virgin aluminum allows for a better pour in the molding process. This results in a tank with much tighter tolerances, greater strength, no chance for leaks, and much stronger brackets.

 

We know that tanks made with this process are much easier to repair, and provide a more solid bond when welding the tank to a new core.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

2. Sand Cast Tanks – these tanks are made in sand cast molds and are produced for the replacement market. They are reversed engineered using 99% recycled aluminum materials. This results in a much greater risk of leaks due to high porosity, lower quality weld because of excessive contamination, and improper bracket alignment due to low-grade materials and inconsistent pour.

 

Characteristics:

Sand Cast tanks are porous, inferior to permanent steel mold tanks, and are sold only as an aftermarket item.

At 100 psig the header

plate separated from

the top plate.

At 120 psig a tube cracked.

At 120 psig, there was also a distortion at the header plate.

Standard OEM Core A

Non-Fleet Air

Replacement Core

 

These results are credible evidence that not all cores are built alike. They show failures at pressures ranging from 100 psig to 560 psig. When choosing a company to provide you with charge-air-cooler cores for your truck or fleet, be sure to get the most specific details possible regarding core construction.

 

At 250 psig, an audible popping caused by fins breaking away from tubesFinal failure occurred at 300 psig with the tubes visually ballooning.

At 500 psig audible popping began, which was caused by the fins breaking away from the tubesFinal tube failure occurred at 560 psig.

 

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