Intercoolers cut down the engine oil temperature when connected to the forced induction system.
The modern engines are powered by different techniques to increase power from the same displacement. The turbocharged and supercharged engines usually increase the engine pressure during the combustion process hence the internal engine temperature increases drastically.
The turbochargers and superchargers heat up the air going into the engine to ease the combustion system. This process works far differently from the conventional and naturally aspirated engines as this system drastically reduces the air density which clearly means less oxygen to burn in the combustion chambers.
Less oxygen means bad combustion which leads to restricted power production. The reduced power ultimately decreases the performance of the engine and eliminates the benefits linked to the power delivery.
This is where a need of turbochargers arises to forcefully induce the air into the combustion chambers. The air flowing into the combustion chambers through the turbochargers or superchargers passes very close to exhaust ways as this is the exhaust gases driving the turbochargers, they increase the air temperature.
This hot air further increases the chance of detonation and even pre-ignition in petrol engines. This practice is usually not admired in the petrol engines however, diesel engines can also face problems by increased air temperatures and internal engine temperature by ramping up the thermal loads on the engine parts and the induced air also reduces the engine power.
This is where the need for air conditioning arises and in order to avoid the issues, charged air cooling devices are used and these devices called intercoolers. These intercoolers as their name explains cools the air and reduce the temperature of the pressurized air charge.
The intercoolers cool the air through outside air or liquids. There are two types of intercoolers used in the engines, one is called air cooler and the other is called oil cooler. It is all about the thermal treatment in an engine and it increases the density of the air by reducing the thermal stresses.
What is an intercooler?
The intercooler is a device that reduces the temperature of the air or the gasses flowing into the combustion chambers of the engine. Historically these parts were called heat exchangers and were positioned between compression stages.
In the turbocharged or supercharged bigger engines, air flows from turbochargers to intercoolers and then to the superchargers. Generally, the term intercooler applies to an air to air heat exchanger.
How does an intercooler work?
The intercoolers work in the same way as the radiators work in the engines, radiators reduce the heat of the engine block through liquids and thus the intercoolers reduce the temperature of the air flowing into the engine.
Conventionally, the forced air fed into the intercoolers and the cooling mediums e.g. ambient air cools the internal air by passing through the fins of the intercoolers. This way, the charge and the temperature both decreases and the density of the air increases.
There are different sources used to cool the internal air, the air to air intercoolers use fresh air to stabilize the temperature and usually mounted in front of the radiators. This way same air passing through the radiator passes through the intercooler and cools the air.
If the cars have different engine positions e.g. in Subaru and Mini, the intercoolers mounted on the top of the engine and you can clearly see an air inlet on the top of the bonnet. This configuration is easier to handle and safer then intercooler.
Similarly, in the rear and mid-engine cars, intercoolers usually fitted in the rear wings. The air ducts supply the fresh air to the intercooler to work properly. Some of the later models like Porsche 930s have same configurations.
Some larger vehicles have an outbound larger duct to suck the air into the intercoolers and engine as well. The performance of the intercooler can be increased by spraying the water into the airways or spraying the nitrous oxide or carbon dioxide over the air ducts. These practices can reduce the air temperature even swiftly and rapidly.
What about a water-to-air intercooler?
This technique of cooling air in the combustion systems sometimes is called charge cooling system. The word charge is used because the system uses water to reduce the temperature of the induced air going into the system.
Usually, water is pumped through the waterways around the air ducts. The waterways around the air ducts dramatically decrease the temperature of the air and increase the density. This water then passes through the radiator which actually uses the ambient air to cool the entire system.
The water-cooled intercoolers are relatively easy to be used in the engines and the cooling system offers more benefits than the air-cooled intercoolers. At the same time, these intercoolers are even heavier and costly as well but the performance leaves everything behind.
The air to air intercoolers can be tweaked for boosted performance by adding chilling chambers into the system.
Common types of intercoolers
As discussed in the past passages, there are two major types of intercoolers used in the majority of vehicles these days, where an air to air intercooler and a water to air intercooler is most common.
A pressurized charge passes through the heat treatment exchangers and the ambient air cools the system and air flowing inside it. This system although a commonly used system but has limited performance compared to the water to air cooled system.
The second type of water to air cooling system is more effective and reliable as it cools the air through the liquid. Heat transferred to the water and hot water pumped into the radiator for further cooling. Radiators itself cooled by the massive suction of the air.
Can an intercooler be used on a naturally aspirated engine?
It is not an impossible thing to do but keep in mind the working of an intercooler that it is just used to decrease the air temperature flowing into the combustion chambers. The air only got heated when compressed by the turbochargers and intercoolers reduce the temperature by cooling the air.
In naturally aspirated engines, the ambient air is going into the engine so there is no reason left to use an intercooler. It would not increase the performance of the engine at all. A conventional intercooler doesn’t have the ability to cool the air below ambient air temperature thus there would not be any benefits.
Anthony Arnold is an automotive expert and loves to share his experiences. For the last ten years he is in used and reconditioned engines business.