In car engines that are either supercharged or turbocharged, whenever the boost pressure is raised, the air being fed to the engine also gets hotter. This causes problems because hot air is less dense than colder air. When there is less dense air, there is less oxygen, which is needed to burn the fuel that is being used. Additionally, when the cylinders are filled with hot air, the risks that the gas can catch on fire increase. This can also be a problem for vehicles that use diesel fuel. There are ways to prevent this problem. Many people turn to inter coolers to lower the temperatures of the pressurized air. Depending on the heat exchanger design, the cooling happens with either cool air or cool liquid. The air that has been pressurized is forced through the temperature controllers, the air is cooled. This makes the air denser, which prevents many of the heat-related problems.
You may be asking yourself, “What are inter coolers?” That is a good question. Traditionally, these were heat exchangers that were placed in between different stages of the compression process in engines. One example is military aircraft where intercoolers are put in between the turbocharger and supercharger. Times have changed, however, and today when people refer to inter coolers, they are talking about any heat exchanger that uses an air-to-air system.
When you look at inter coolers that use the air-to-air, you can see that the main difference between them and radiators is that the radiators have coolant. Air-to-air units do not need anything but air. Typically, a charge is put through the unit and the coolant. Here that coolant is just air that goes through the fins of the unit. When the cool air enters the engine, it is denser than the hotter air.
These kinds of inter coolers do need to have access to fresh, cool air. When they are used in vehicles where the engine is in the front, they are usually placed either in front of the radiator or next to it. Some car manufacturers place them on the top of the radiator.
For vehicles that have their engine in the back, the intercooler is placed behind the radiator. Ducts are then installed to move the cooler air where it needs to be. There are cars with engines in the rear that use an inter cooler that has been placed on top.
In a number of cases where the engine is located at the rear of the vehicle, the heat exchanger’s power is increased by spraying nitrous oxide, carbon dioxide, or water to lower the temperature. When any liquid is added, when it moves from the liquid state to a gaseous one, the cooling effect is augmented.
There are other kinds of inter coolers. Some use a system, called charge-cooling. This term generally refers to cooling where rather than using an air-to-air system, a liquid-to-air method is employed. Most of the time, the liquid in question is water. This liquid is moved through the heat exchanger system. This lowers the air temperature going into the engine.
Systems that use water to cool the air in the engine may be more complex but there are great reasons to consider this option. They can be a lot easier to put into the engine bay. Parts of this system can be placed in another area. The downsides to this option are that it does cost more to get a liquid system and they are heavier, which will mean it takes more fuel to move your vehicle. There are ways to improve the cooling power.
There are vehicles for which inter coolers really do not make much sense. For example, if your vehicle is aspirated naturally, you may not see any difference once you have installed a heat exchanger. Because of the inherent cooling that happens with engines in these kinds of vehicles, there really is no need to add a separate accessory to cool the air further. Another reason is that these vehicles already cool the air in the engine to the temperature of the air around the vehicle. Even the most powerful heat exchanger cannot get air to be cooler than the air around it.