When gas is compressed it heats up, because all the molecules are being pushed together it heats them up.

It's the same with a turbo blowing air into an engine, but because hot air contains fewer molecules than cool air, this essentially means the engine isn't getting as much oxygen as it needs to produce power.

An intercooler is situated 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 works by cooling the air down.

As the air cools it becomes denser, meaning 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.

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.

How does an Intercooler Work?

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