Intercooler: how does it work and why does your car need one?

If you have a car with a turbo engine, either gasoline or diesel, it will almost certainly have an intercooler. I say almost certainly because there are also cars with supercharged engines that do not have an intercooler. In fact, in the decade of 80s and 90s, it was even used as an advertising claim, and there were cars that “boasted” with the anagrams “Turbo Intercooler”, just like those of “16V” or “GTI” were used.

What is the function of the intercooler?

An intercooler is a radiator, which is used in supercharged engines, either using a turbo or a compressor. The function of the intercooler is to cool the air that the supercharger system sends compressed to the intake.

Why is this done? Well, because the air, due to the compression of the turbo, heats up, increasing its temperature a lot, which causes its density to decrease. In other words: if the air compressed by the supercharging system goes directly to the intake without going through the intercooler, it has less oxygen than if its temperature is reduced; And remember, the principle of the supercharger system is to introduce more air than the engine can naturally draw in, so that combustion occurs with more oxygen, thus improving performance.

Types of intercooler

There are two types of intercoolers, air intercoolers, in which cool moving air from outside is used to reduce the temperature of the compressed air. And the water intercoolers, in which the heat transfer system is a coolant.

The advantage of the former is that they are simpler, while the latter is more efficient (water has a greater cooling capacity than air) and can be smaller.

Where is the intercooler placed?

Audi Intercooler

The intercooler is always placed in the circuit that the exhaust gases travel from the turbocharger to the intake. The engineers look for the best possible compromise so that the path of the gas flow is as short as possible, and that the radiator is positioned in the most favorable way to receive the outside air.

The location in the engine compartment will depend on the type of engine (number and arrangement of cylinders) and the type of intercooler (air or water). The air ones need to be installed in the front part to receive the highest possible flow of outside air. The water pumps can be installed anywhere in the engine compartment, but they also need to receive external airflow.

As an illustration of how the placement of the intercooler affects the performance of the engine, I remember years ago measurements on the power bank of cars with the intercooler placed in a horizontal position, which received the air through an intake in the hood. As on a roller bench with the car stopped it was difficult to achieve an equivalent airflow based on fans, to get more “real” power measurements it was necessary to place ice just above the intercooler.

Intercooler

You also have to know that an engine can have several intercoolers. For example, one for each row of cylinders in V-engines, or two smaller cylinders in parallel (instead of just one larger one) to increase efficiency in in-line engines where there is little space.

Maintenance and breakdowns

Normally an intercooler does not need maintenance beyond checking that there are no leaks in the pipes.

A “silly” fault that is easy to solve is the looseness of one of the hoses that are connected to the intercooler, usually due to deterioration of the flange that holds it. The symptoms are a sudden and distinct loss of engine power and the appearance of a perceptible “hiss” when accelerating. If there are no other associated problems, simply reconnect the sleeve and use a new flange. The sleeves themselves can also show aging cracks.

An intercooler can also lose efficiency if the radiator fins are damaged, for example by the impact of stones. In case of problems with the turbocharger, it is necessary to check the intercooler, which can be contaminated by the effect of oil leaking through the damaged gaskets of the turbocharger.

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