In our Intercooler Guide (Part 1) post, we covered the differences in air-to-air and liquid-to-air intercoolers and provided some general advice from Mishimoto about which might be right for you. Once you’re done making that choice, you’ve still got some important decisions to make.
In Part 2 of our guide, we’ll show you how construction can influence the effectiveness of an intercooler and further help you make good decisions for your application. With help from our friends at Mishimoto, we’ll cover the three main areas of an intercooler: core, end tanks, and piping. Each one of these areas plays a key role in the effectiveness of the intercooler.
Selecting a good quality core is essential when choosing an intercooler for your ride.
There are two main types of intercooler core designs: tube-and-fin, and bar-and-plate. Tube-and-fin cores are common on stock intercoolers, but not on performance aftermarket intercoolers. That’s because these types of intercoolers are prone to heat soak in hot engine bays or when repeated pulls cause the intercooler to overheat. This heat soak can result in power losses as the ECU adjusts for the higher intake temperatures.
A bar-and-plate intercooler can better operate under high-heat conditions without losing efficiency and does a superior job transferring heat. The inherent design of a bar-and-plate core promotes better heat transfer and is better at handling high-boost applications than a tube-and-fin core. The ability of a bar-and-plate core to handle high boost is determined by the thickness of the braze sheets, fins, side bars and top plate. Another benefit of a bar-and-plate design is its ability to withstand the potential abuse from being mounted at the front of a vehicle. The drawbacks to bar-and-plate intercoolers are added weight (compared to tube-and-fin) and higher costs.
But then again, you get what you pay for.
Here’s a quick comparison, courtesy of Mishimoto:
Fin style and density also play a part in the performance of an intercooler. More fins equal better heat exchange; however, high fin density will reduce airflow through the intercooler. Finding the right balance can be a challenge, but intercooler manufacturers use a variety of equations and testing to come up with the optimal solution for each application. This often includes experimenting with the pitch and overall height of the fins to create the right amount of surface area.
Another consideration is core size. The bottom line is bigger is not always better when it comes to intercooler core size. A properly sized intercooler will deliver efficient cooling without impacting boost lag.
Mishimoto put together a handy chart to match core size to your vehicle’s horsepower.
In the chart, the “high-density core measurement” of an intercooler can be determined by using a couple of equations.
Core Area (in²) = Core Length (in.) x Bar Height (in.) x # of Bars
For example, a 22-inch long core with 12 bars that measure .3 inches will equate to:
Core Flow Area = 22 x .03 x 12
Core Flow Area = 79.2 in²
Once you know the Core Flow Area, you divide that number by .45 to determine the Charge-Air Surface Area.
Charge-Air Surface Area (in²) = Core Flow Area (in²) /.45
For our example, that means we have:
Charge-Air Surface Area = 79.2 in² / .45
Charge-Air Surface Area = 176 in²
Lastly, you divided the Charge-Air Surface Area by the core thickness to determine the Internal Flow Area, which is denoted as the “high density core” measurement in the chart.
Internal Flow Area (in²) = Charge-Air Surface Area (176 in²) / Core Thickness (3.75-inch)
Internal Flow Area = 47 in²
According to the chart, this intercooler would be effective up to 500 horsepower.
The right end tank is a major factor in the longevity of your heat exchanger and have a big effect on the airflow through the core. There are four common materials used for end tank construction: plastic, stamped aluminum, cut-and-weld aluminum, and cast aluminum.
Plastic end tanks are used on stock intercoolers, but they are not ideal for performance applications. These end tanks are not well equipped to handle increased performance or higher boost levels. As a result, they can outright fail during high-boost pulls.
Aluminum tanks are recommend for performance applications. Stamped aluminum tanks are the most budget-friendly aluminum option and can easily handle high-boost applications. However, you’ll most commonly find stamped aluminum end tanks paired with standard tube-and-fin intercoolers. Cut-and-weld aluminum end tanks are considered a step up from stamped tanks. A well made cut-and-weld tank provides fantastic durability; however, since it incorporates multiple pieces of aluminum welded together, proper testing and precision welding is required.
Cast aluminum end tanks are at the top of the spectrum. These tanks offer the best combination of reliability and smooth airflow. Because there are no welds, there are no potential failure points. And since the internal structure is smoother than cut-and-weld tanks, engineers can optimize the airflow to the entire length of the core.
You will have to match your piping to the outlets on your intercooler. Therefore, the size of the outlets are important, especially when you consider the effect of intercooler pipe size on performance. It really is a delicate balance between airflow and horsepower output. For example, piping too large will require greater flow to produce boost, causing lag. Conversely, piping too small will limit the power output.
Mishimoto recommends you run the smallest piping possible without causing restrictions. The company offers this chart to make the choice a little easier.
As you can see, a three-inch pipe is capable of handling in excess of 800 horsepower—adequate for many performance setups.
Armed with this information, you’re well on your way to choosing the right intercooler for your vehicle.
Happy intercooler shopping!