What Does an Intercooler Do?

Turbochargers heat up the air, and hot air is not suitable for power production for a very good reason, so it needs to be cooled down before getting to the engine

Compress a gas and it heats up. Pump up a bicycle tire with a handheld pump and it gets hot. This is because all the air molecules are being pushed together and that heats them up.

It’s the same with a turbo blowing air into an engine, and since hot air contains fewer gas molecules than cool air, this essentially means the engine isn’t getting as much oxygen as it should produce power.

How does an Intercooler Work?

An intercooler solves this by sitting between the turbo and the engine air intake. The hot air from the turbo passes through the intercooler, which is basically a big radiator, and cools down. The air becomes denser, so there’s more oxygen in any given volume, which is what burns in the engine and makes the power. One BAR, or 14.7PSI of boost increases the air temperature by approximately 60 degrees Celsius, while every 37.8 degrees Celcius reduction in air temperature increases air density 12-13 percent.

What Intercoolers are Available?

The most common intercoolers are air to air – with intake air running through the bars. They are light and simple, but you can get air to fluid intercoolers, where fluid runs through the bars and then runs through a separate radiator that the intake air is running through. These are obviously much more expensive though and are really only used in very extreme conditions.

Is a Bigger Intercooler Better?

The size of the intercooler is important – if it is too big for the turbo will take a long time to fill the intercooler with air and throttle response will be delayed. Positioning is also important. Front mount intercoolers are the best for efficiency, where they can get a good flow of cooling air right through the front bumper.

Top mount intercoolers as on Subaru Impreza WRXs are not ideal as heat soak from the engine can degrade the intercoolers’ function. Top mount intercoolers do have one advantage though because they are located close to the engine and don’t require long connecting pipes that can also degrade throttle response.

Where Should an Intercooler Go?

The best place for an intercooler, in terms of power production, is behind the front grille of the car. Many performance car owners simply remove the air conditioning radiator and replace it with an intercooler. Every turbo set-up should include an intercooler, otherwise, potential power is simply being wasted. The good thing is that you can find intercoolers at any performance shop, usually already made for specific models of cars.