How a Cold Air Intake Improves Horsepower

April 19, 2013

When looking for ways to improve the performance of your vehicle, cold air intakes are a common first step due to their reasonable costs and ease of installation. Most notable and most easily recognized are the AEM intake and K&N intake systems due to their extensive history and market share. These units are attractive and well designed and can be installed in as little as an hour. While these reasons may show why they are so popular, understanding how they go about improving power takes a bit of explanation.

Power Through Colder Air

Just as the name implies, cold air intakes improve power primarily due to where they get their airflow. Cooler air, such as air from the inner fender is more dense than hot air found in the engine bay, and as such, contains more oxygen, which combined with additional fuel, makes more power. In addition to denser more oxygen rich air, a cooler intake charge has additional benefits when it comes to ignition timing. Cooler intake air temperatures are less likely to cause detonation so on most modern fuel injected engines, the computer will allow more advanced ignition timing, which can improve power in naturally aspirated engines, and reduce lag in turbocharged engines.

Improved Airflow

Factory intake systems are designed with several goals in mind aside from power production. To appeal to the widest range of customers possible, factory intake systems are designed to be as quiet as possible and to operate is as many environmental conditions as possible to minimize warranty concerns. The problem is that quiet intake systems generally achieve this subdued volume by designing in restrictions which can reduce potential power in favor of avoiding induction noise and intake honk. In addition, concerns about water ingestion rank very high on the manufacturerÂ?s list of design parameters. So often times, a source of cooler air may be overlooked in favor of a safer location. Cold air intakes generally have a much more direct path for airflow that draws its air from colder locations to maximize power.

Resistance to Thermal Contamination

Cold air is only one part of the puzzle when it comes to improving performance. While air may be cool and dense when it enters the intake, poor design and poor insulation may heat the air as it makes its way to the engine. Any heating of the intake air largely defeats the purpose of a cold air intake to begin with, so many well designed units will incorporate a variety of methods for combating this thermal contamination. These methods may range from the use of a material that resists heat transfer, such as some types of plastic or composite, to coating the intake with a zirconium or ceramic based thermal barrier. All of these methods help to keep the air as cold as it was when it entered the intake.

Aside from an increased risk of water ingestion during heavy rainfall, most intakes offer improved performance with almost no downsides other than increased engine noise. If you are just getting started with automotive performance, consider trying a cold air intake, as they can add substantial performance without commanding a heavy price tag or intimidating installation directions.