For many car fans, the intercooler in the front bumper is a coveted modification part and an indispensable symbol of performance, just like the sound of the pressure relief valve. However, what is the knowledge behind the various intercoolers that appear to be the same on the outside? If you want to upgrade or install, what should you pay attention to? The above questions will be answered one by one in this unit.
The installation purpose of the intercooler is mainly to reduce the intake air temperature. Readers may ask: Why do we need to lower the intake air temperature? This brings us to the principle of turbocharging. The working principle of turbocharging is simply to use the exhaust gas from the engine to impact the exhaust blades, and then drive the intake blades on the other side to force compress the air and send it to the combustion chamber. Since the temperature of the exhaust gas is usually as high as 8 or 9 Baidu, which also puts the turbine body at an extremely high temperature, which will increase the temperature of the air flowing through the intake turbine end, and the compressed air will also generate heat (because the distance between the compressed air molecules becomes smaller, it will If this high-temperature gas enters the cylinder without being cooled, it will easily cause the engine combustion temperature to be too high, which will then cause the gasoline to pre-combust and cause knocking, causing the engine temperature to rise even more. The volume of compressed air will also greatly reduce the oxygen content due to thermal expansion, which will reduce the supercharging efficiency and naturally cannot produce the desired power output. In addition, high temperature is also a hidden killer of the engine. If you do not try to lower the operating temperature, once you encounter a hot environment or drive for a long time, it is easy to increase the chance of engine failure, so it is necessary to install an intercooler. to reduce the intake air temperature. After knowing the function of the intercooler, let's discuss its structure and heat dissipation principle.
The intercooler is mainly composed of two parts. The first part is called Tube. Its function is to provide a channel to accommodate the compressed air to flow through. Therefore, the Tube must be a closed space so that the compressed air will not leak pressure. The shape of the Tube is also divided into square and oval. The difference lies in the trade-off between wind resistance and cooling efficiency. The second part is called Fin, which is also commonly known as fin. It is usually located between the upper and lower layers of Tube and is tightly bonded to the Tube. Its function is to dissipate heat, because when the compressed hot air flows through the Tube, it will dissipate heat. It is transmitted to the fins through the outer wall of the tube. At this time, if air with a lower outside temperature flows through the fins, the heat can be taken away to achieve the purpose of cooling the intake air temperature. After the above two parts are continuously overlapped together, the structure up to 10 to 20 layers is called Core, and this part is the so-called main body of the intercooler. In addition, in order to allow the compressed gas from the turbine to have space for buffering and accumulating pressure before entering the Core, and to increase the air flow rate after exiting the Core, parts called Tanks are usually installed on both sides of the Core. It is shaped like a funnel, and there will be a circular inlet and outlet on it to facilitate the connection of the silicone tube, and the intercooler is composed of the above four parts. As for the heat dissipation principle of the intercooler, it is as mentioned just now. It uses numerous horizontal tubes to divide the compressed air, and then the direct cold air from the outside at the front of the car passes through the heat dissipation fins connected to the tubes to cool the compressed air. The purpose is to make the intake air temperature closer to the outside temperature. Therefore, if you want to increase the heat dissipation efficiency of the intercooler, you only need to increase its area and thickness to increase the number, length and cooling fins of the tube, etc., to achieve this goal. But is it that easy? In fact, this is not the case, because the longer and larger the intercooler is, the easier it is to cause the problem of intake pressure loss, and this is also one of the main issues discussed in this unit. Why does pressure loss occur?
For an intercooler that emphasizes performance, in addition to having good heat dissipation capabilities, the reduction of pressure loss must also be taken into consideration. However, suppressing pressure loss and improving cooling efficiency are completely opposite in terms of skills. For example, an intercooler with the same volume and size must If the intercooler is designed based entirely on heat dissipation, the tube inside will need to be made thinner and the number of fins will be increased, which will increase air resistance; but if it is designed to maintain the pressure level, the tube and tube must be thicker. Reducing the fins will result in poorer heat exchange efficiency, so the modification of the intercooler is by no means as simple as we imagined. Therefore, to balance cooling efficiency and pressure maintenance methods, most people will start with the tube and fins.
Next is the fin part. The fins of a general intercooler are usually straight in shape without any openings. The fins are as long as the width of the intercooler is. However, since the fins are in the entire center In the intercooler, it plays the main role in the heat dissipation function. Therefore, as long as the area exposed to the cold air is increased, the heat exchange power can be improved. Therefore, many intercooler fins are designed in various forms, including wavy or Fins commonly known as louver designs are the most popular. However, in terms of heat dissipation efficiency, overlapping heat dissipation fins are the best, but the amount of wind resistance generated is also the most obvious, so it is more common on Japanese D1 racing cars, because these racing cars are not fast, but they need good Cooling effect to protect the engine running at high speeds. Perform intercooler modification. [2]
Depends on turbine capacity
After talking about the various theories of intercooler modification, what are the things that need to be paid attention to during actual modification. Generally speaking, intercoolers for modification are mostly divided into original replacement types and large-capacity kits that require significant changes in pipeline configuration. The specifications of the direct exchange type are similar to those of the original factory. The only difference is that the internal tube and fin design are different and the thickness is slightly wider. This kit is suitable for vehicles that have not been modified by the original factory, or where the modification is not extensive. It can replace the original engine potential is unleashed. As for large-capacity intercoolers, in addition to increasing the windward area to enhance heat dissipation, the thickness will also be increased to ensure constant temperature. Taking the intercooler produced by Haoyang as an example, the general type is about 5.5 to 7.5 centimeters (suitable for (for vehicles with 1.6 to 2.0 liters), the reinforced type is about 8 to 105 centimeters (for vehicles with 2.5 liters and above), and a large funnel-shaped air storage tank will be used to minimize the resistance to air flow. Of course, the use of enhanced intercoolers is more suitable when equipped with medium and large turbines. For example, it is not recommended for engines below the No. 6 turbine, because the lag will be more serious and is not conducive to low-speed boost response. However, in vehicles modified from NA to Turbo, it is better to have a larger intercooler, because the cooling efficiency of the original design may not be enough. In addition, even at low boost settings, the intercooler cannot be omitted. After all, the air intake is relatively low. Temperature can not only extend the durability of the engine, but also help stabilize the power output.
On the other hand, in addition to using air for heat dissipation, the intercooler also uses water cooling. The Toyota Mingji 3S-GTE is an example. Its main advantage is that the Cooler body is located just in front of the throttle, so the intake pipeline is extremely short. The characteristics of high response, coupled with the very high constant temperature of water itself, are also very helpful to the stability of the intake air temperature, especially when there is no wind impact at the front of the car, such as a traffic jam. However, since it requires a separate dedicated water pump and water tank radiator, and the temperature reduction is not as great as direct air cooling, air-cooled intercoolers are still the mainstream. [2]
Prioritize linearization
As for the installation position of the intercooler, it is generally divided into two types: front-mounted type and top-mounted type. In terms of heat dissipation, the front-mounted type located in the front bumper is of course better, but when it comes to reactivity, it is the upper type. The front-mounted intercooler is cheaper, which is the direct effect of supercharging caused by its short pipeline. For example, in order to shorten the pipeline of the front intercooler, the Impreza WRCar reverses the throttle to reduce the pressure loss caused by the too long pipeline. , it is not difficult to imagine that the overall matching of the intake pipe is also the key point that must be paid attention to when modifying the intercooler. Therefore, when upgrading or installing an intercooler, in addition to paying attention to the size of the intercooler, the length of the pipeline should be shortened as much as possible and straightened to reduce bends, welding points, etc., which are all ways to increase the air flow rate , because if there are too many solder joints and corners, the smoothness of the air flow will definitely be poor and pressure loss will occur.
Secondly, just like the principle of the intercooler discussed earlier, if the tube of the intercooler is too thin, it will easily increase the resistance and affect the reaction, and the temperature in the tube wall will be higher. Similarly, slightly thickening the diameter of the intake pipe is also a good method. As for this The matching of pipe diameter mainly depends on the diameter of the turbine outlet and throttle. It is worth mentioning that the diameter of the inlet and outlet pipes before and after the intercooler should be about 10% thicker after the outlet than before the inlet. The reason is that the larger outlet pipe diameter can allow the cooling air of the Core to escape. Passing through the intercooler at a faster speed can positively help increase the flow rate. As for the material part of the intercooler, it is usually made of aluminum alloy. It not only adds texture and improves the appearance, but also increases the heat dissipation effect due to the high thermal conductivity of aluminum. In addition, it has the advantage of being lightweight, so aluminum alloy is also chosen. One of the main reasons. As for the rubber connecting pipe between metal pipes, it is recommended that you use silicone rubber products covered with three or five layers as much as possible. This kind of silicone pipe has excellent ductility, can withstand high temperatures and high pressures, and will not harden, so it can be used as small as vacuum pipes, Medium-sized water pipes and large-sized air intake pipes are very good original replacements. They are very suitable for use in high-heat turbine engines. Coupled with the fixation of wide-type clamping stainless steel bundle rings, they can avoid pipe bursting or air leakage. The problem arises, and it is different from the original black color, which is of great help in improving the combat atmosphere of the vehicle, so that the car owner can drive the car with confidence. [2]
Setting selection
I believe that when upgrading the turbine, many Impreza owners wonder whether it is better to use the original factory upper-mounted enlarged intercooler design, or directly switch to a front-mounted intercooler? To solve this problem, it needs to be determined by the number of upgraded turbines. Since the exhaust head section of the horizontally opposed engine is longer than that of the straight engine, it also makes the low-speed boost response slower. Therefore, the original manufacturer will design an upper-mounted intercooler to reduce the problem of turbo lag. If it is upgraded When the turbine number does not exceed No. 6 and the displacement is less than 2.2 liters, the author does not recommend switching to a front-mounted intercooler, because the extended pipeline and enlarged intercooler will make the lag problem more serious. However, when you meet the above conditions, you can consider switching to a front-mounted intercooler. On the one hand, the cooling efficiency of the top-mounted intercooler is no longer sufficient, and on the other hand, the large turbine air supply volume and flow rate are large. It is faster and the impact on the extended pipeline can be minimized, so it is more suitable to use a front-mounted intercooler.