Cold air intake
|
|
A cold air intake is a system to bring down the temperature of the air going into a car for the purpose of increasing the power of the internal-combustion engine. A secondary goal is to increase the appeal of a car by changing the apperarance of a car's engine bay and creating an attractive intake noise. These aftermarket parts come in many different colors and many different sizes, and are an inexpensive way to increase performance.
All cold air intakes operate on the principal of increasing the amount of oxygen available for combustion with fuel. Because cooler air has more oxygen for a given volume, cold air intakes generally work by providing cooler air from outside the hot engine bay. However, the term "cold air intake" is often used to describe other methods of increasing oxygen to an engine, which may even increase the temperature of the air coming into an engine.
Some strategies used in designing cold-air intakes are:
- increasing the diameter of the air intake, allowing increased airflow.
- smoothing the interior of the intake to reduce air resistance.
- providing a more direct route to the air intake.
- tuning the length of the intake to provide the most airflow at certain RPMs.
- using a more efficient air filter
The most basic cold air intake replaces the stock airbox with a short metal pipe leading to a conical air filter, called a Short ram air intake. The power gained by this method is usually minimal. The placement of the filter is usually directly in the engine compartment, allowing heated air to enter the engine, reducing performance. This may be offset by an increased volume of air, however, and the overall gain or loss in performance depends on the specific application. Power may be lost at certain engine speeds, only to be gained at others. Because of the increased airflow and reduced covering, intake noise is usually increased. This effect is usually amplified as this method removes the resonator, a part intended to reduce intake noise.
Better designed intakes use heat shields to isolate the conical filter from the rest of the engine compartment, providing cooler air from the front or side of the engine bay. Carbon fiber can be used for the piping instead of metal, lowering weight and insulating the air from the engine bay somewhat.
The most extreme designs route air from outside the engine bay, usually from the wheel wells, front grill, or a hood scoop. The intake can be placed such that the forward motion of the car pressurises the air coming in, creating a ram-air intake
The best cold-air intakes are optimized for a specific engine application, providing increased airflow at ambient temperature and raising power at all engine speeds.