The following info applies to air to air applications.
Remember that there's a balancing act between cooling and airflow restriction within the core. The more densely packed turbulators are within a bar and plate core the more cooling will be done as the air passes through, but the greater flow is restricted. Alternatively, air blowing straight through a pipe isn't restricted or cooled much at all.
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On this page, you will learn nearly everything about intercoolers and how they function.. We will explain everything from the basic design, tube types, internal design and upsides and downsides of each. At the end we describe Extreme Turbo Systems intercooler design.
Tube Design: First we will discuss the two main types of tube design, square tube and oval tube. The square tube is used in bar & plate core, and the oval tube are used in the tube and fin and hybrid fin cores. The following two pictures show the tube design as if you were looking down the length of the core. Usually when looking at an intercooler that is installed on a vehicle, you see the front/back side of the tubes, either the flat end of the bar and plate, or the rounded nose of the tube and fin. Cores are usually rated based on height, where there is usually one tube per inch of height and rated in cfm. Square Tube:
Oval Tube: Bar
Ambient Airflow: Between the two tube designs, external ambient airflow through the core is different. With the square nose design of the bar and plate, the flow of ambient air through the core is slightly worse than the tube and fin due to wind deflection off of the square face. Usually this is not an issue on core thicknesses up to 4" thick. In some cases with thicker cores, the bar and plate may cause some vehicles to run a couple degrees hotter at low speed. At higher speeds above 40 mph there is rarely an issue. Square Tube Ambient Airflow
Oval Tube Ambient Airflow Bar Airflow
Internal Tube Design: Next we will discuss the 3 main types of core design--bar and plate, extruded tube and fin, and hybrid fin.
Bar and Plate: The bar and plate design uses a square tube with a fine internal fin packing. This fine internal fin packing allows this type of core to be very efficient but due to the turbulence caused by the larger amount of fins, flow is slightly sacrificed. Since the square tube has a larger internal area compared to a oval tube of the same thickness this core still flows more air per tube compared to the other two designs.. The upsides of this core is the high efficiency and it is available in thicknesses from 3" to 5". The downside is that due to the square nose design, ambient airflow through the core is somewhat sacrificed.
Extruded Tube & Fin: Extruded Tube and fin design uses a oval tube with an extruded fin that is molded into the tube when it is built. The fin packing is not very dense which lowers the efficiency of the core but allows it to flow more air through each tube because there is less turbulence caused by the internal fins. A lot of the time the air charge will nto contact any of the fins as it travels through the core. There are several types of extruded tube and fin designs, but it is usually the least desirable since it has the lowest efficiency therefore the lowest temperature drop across the core. This can commonly lead to heat soak. The upside to this type of core is that due to the oval nose design it allows more ambient airflow through the core compared to the bar and plate and because the fin packing is not as dense, it flows well through the core (internally). The downside is that the core design is very inefficient.
Hybrid Fin: This design is a hybrid between the bar and plate and tube and fin. This type of tube uses the oval tube like the tube and fin and the dense internal fin packing like the bar and plate. The upside to this design is that it is nearly as efficient as the bar and plate, and allows more ambient airflow through the core (external airflow). The downside of this type of core is that the thickest core that is usually offered in this type is between 2.5" to 3" thick and becoming difficult to find. Griffin uses a hybrid fin type core, but the tubes are taller than average which flow well, but since the heat has to travel so far from the center of the fin to the tube wall it slightly lowers the efficiency but with the larger tube, improves airflow through the core. Bar and Plate
Tube and Fin
Hybrid Fin Bar & Plate
Fin Packing: Here we talk about the fin packing, internal and external design. For the intercoolers that use a fine internal fin packing there are two configurations. There is the standard packing and there is the staggered fin packing. In the standard fin packing all of the fins are in-line. If you look down the tube of this design you will usually see light through the other end. In the staggered fin packing the fins are staggered so more of the air comes into contact with the fins. If you look down the tube in this design you will rarely see any light from the other end. This design is superior because it is more efficient from the air coming into contact with more fins, but will slightly hinder flow but not significantly unless it very densly packed. There are some companies that use a very dense fin packing which is one of the most efficient on the market, but also flows the least because of it. The same applies for the external fin packing between each tube. The external fin packing is usually heavier since they are exposed to oncoming objects such as rocks and debris found on the road.
Fin Design: Another factor that affects efficiency is the fin design. Fins are commonly just thin, flat pieces of aluminum. In some cases these fins are "louvered", similar to what a cheese grater would look like. These little louvers help catch the air and direct it through the fin and improve efficiency allowing the air to contact more of the fins surface area instead of just the leading edge of the fin. Standard Fin Packing
Staggered Fin Packing Inline Fins
Core Configuration: There are two configurations for air to air intercoolers. Crossflow and Vertical Flow. In the pictures below, the tubes are shown in light gray with the fin packing between each tube. The crossflow are the better design because of the effiency of the longer core. Because of the longer core the air stays in the core longer allowing it to draw more heat out of the air charge. Since the crossflow is shorter in height (ie less amount of tubes) it does not flow as much as a Vertical flow core. The vertical flow core, since it has more tubes it flows significantly more air, but because the core is shorter in length, the air doesn't stay in the core long enough to draw a lot of heat out of the air charge. Vertical flow cores work well with very high horsepower applications and is usually recommended for supercharged applications. Crossflow Core (7 Long Tubes)
Vertical Flow Core (19 Short Tubes) Crossflow Core
Vertical Flow Core
Internal Airflow: As airflow travels through an intercooler it chooses the shortest path through the core. In the diagram below it shows a core with 7 tubes, lets say each tube flows 100cfm for a total of 700cfm. If you are only flowing 300 cfm through the core you are really only using 3 of the tubes, the ones directly between the inlet and outlet. As flow increases, it will begin using the upper tubes. This will also help when mounting the intercooler. If the bottom rows were covered by the bumper and the upper tubes were exposed you would not be receiving the maximum performance possible from the intercooler. Internal Airflow @ 300cfm
Extreme Turbo Systems Core: In our quest to develop the best core possible, we tried and tested many cores on the market. In the end we've come to a final product that offers maximum efficiency and maximum flow without making large sacrifices of either one. We took features of some of the better cores on the market and created our own design which we believe is the best on the market.
Our Internal Fin Design: We created an internal fin packing that is staggered and louvered. We were careful to make sure the packing didn't become too dense, sacraficing airflow, but not too light and lowering the efficiency. We found the perfect medium.
Our External Fin Design: Many companies use the same size fin throughout the external fin packing. We created an external fin packing that resists damage from debris yet also increase efficiency. Our core uses heavy duty fins near the front and back of the intercooler core, but as you get closer to the center of the core the fin packing becomes finer and more dense. These small fins transfer heat faster. The combo of these fine external fins and fine internal fins allow our core to be highly efficient internally AND externally.
Intercooler Tanks: With our intercooler assemblies comes a limited lifetime warranty against manufacturer defects. We use heavy duty aluminum on our custom fabricated tanks. Since the weakest point of the intercooler assembly is commonly the welds, we double welded the tanks at the seams on the inside AND outside. The inlet and outlets are hand ported to make sure there is a smooth transition into the itank and then beadrolled so that a hose can be clamped on securely. In some cases we have cast aluminum tanks where the only weld is where the tank is welded to the core.
Final Product: After each intercooler is built we pressure test the whole assembly to 35psi to make sure there are no leaks. All of the welds are inspected to assure they are all up to our quality standards and are visually appealing. The final product is inspected twice for quality, once by a shop team member and once by the owner of Extreme Turbo Systems before it is boxed and shipped to the customer. </poem>