Internal combustion engine
When using forced induction, the air temperature rises dramatically. To cool the air at higher temperatures, an intercooler is needed. An intercooler cools the air before it enters the cylinder (combustion chamber) using air or water. When hot air enters the combustion chamber, it decreases the fuel efficiency as warm air holds less oxygen than cool air. An air to air intercooler uses the cool air from outside to cool the existing hot air as it enters the intercooler. The more surface area the intercooler has the cooler the air can get. There are 2 types of air to air intercooler, the bar and plate intercooler and the tube and fin intercooler. Bar and plate intercoolers can cool the air to lower temperature but a tube and fin intercooler can cost less and also weight less. In air to water intercoolers, instead of using air from outside, it uses a cool liquid to cool the air as it passes though and then uses a radiator to cool the cooling liquid. Air to water intercooler are more complex, heavier and more expensive than air to water intercoolers but can be more efficient than them.