A short ram intake installed in a 2.0L 4-cylinder engine

A cold air intake is a system used 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 appearance of a car's engine bay and creating an attractive intake noise. These aftermarket parts come in many different colors and many different sizes. For other uses, see System (disambiguation). ... For other uses, see Temperature (disambiguation). ... Look up air in Wiktionary, the free dictionary. ... Car redirects here. ... An internal combustion engine is an engine that is powered by the expansion of hot combustion products of fuel directly acting within an engine. ... Aftermarket is an umbrella term for the collective network of vendors who design and sell vehicular components that are intended to replace the stock manufacturers parts in order to alter the appearance or performance of the vehicle. ...

History

The aftermarket company K&N Engineering first offered air intake systems in the late 1980s. Those intakes consisted of rotationally-molded plastic intake tubes and a conical, cotton gauze air filter. In the late 1990s a proliferation of intake manufacturers such as Injen, AEM, Airaid, True Flow, AFE and Volant entered the fray. In addition, oversea manufacturers imported their designs lending to the popularity of Japan domestic market (JDM) air intakes in sport compact markets. K&N and many of the other intake companies now offer intake systems in metal tube designs, allowing a greater degree of customization (the tubes can be powder-coated or painted to match a vehicle). K&N air filter and recharge kit K&N Air Filter is an automotive air filter constructed of cotton gauze material, sandwiched between aluminum wire mesh. ... JDM is an abbreviation or initialism that may refer to: Java Data Mining Juvenile dermatomyositis Japan Domestic Market This is a disambiguation page — a navigational aid which lists pages that might otherwise share the same title. ...

Mechanics

All cold air intakes operate on the principle of increasing the amount of oxygen available for combustion with fuel. Because cooler air has more density for a given volume, cold air intakes generally work by introducing 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. This article is about the chemical element and its most stable form, or dioxygen. ... This article is about the chemical reaction combustion. ... For other uses, see Fuel (disambiguation). ...

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 maximum airflow at certain engine speeds (RPM).
• using a more efficient, less restricting air filter.

Air filter in an Opel Astra car, top side=clean side Air filter in an Opel Astra car, bottom side=dust side Automotive air filter clogged with dust and debris. ...

Application

Intake systems come in many different styles and can be constructed from plastic, metal, rubber (silicone) or composite materials (fiberglass, carbon fiber or kevlar). Due to the limited time air actually remains inside the intake tubing, the materials often do not impact a kit's ability to deliver cool air. The most efficient intake systems utilize an airbox which is sized to compliment the engine and will extend the powerband of the engine. The intake snorkel (opening for the intake air to enter the system) must be large enough to ensure sufficient air is available to the engine under all conditions from idle to full throttle. If the intake opening has an unrestricted opening - no screens or other obstructions - the opening need not be larger than the inside diameter of the engine's throttle body, airhorn, or carburetor throat. Under some conditions Intake system efficiency can be lost if the intake opening for the airbox is too large.

The most basic cold air intake replaces the stock airbox with a short metal or plastic tube leading to a conical air filter, called a Short ram air intake. The power gained by this method can vary depending on how restrictive the factory airbox is. The placement of the filter is usually directly in the engine compartment. The overall benefits depend on the specific application. Power may be lost at certain engine speeds, and gained at others. Because of the increased airflow and reduced covering, intake noise is usually increased. This effect is usually amplified on applications where a resonator, a part intended to reduce intake noise on some vehicles, is replaced by the intake. The introduction of this article does not provide enough context for readers unfamiliar with the subject. ...

Well designed intakes use heat shields to isolate the air 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, reducing weight and insulating the air from the engine bay in some cases. Carbon fiber and other advanced composites (such as Kevlar) are expensive, and can be more aesthetic rather than functional. Graphite-reinforced plastic or carbon fiber reinforced plastic (CFRP or CRP), is a strong, light and very expensive composite material or fibre reinforced plastic. ...

Air bypass valves are gaining popularity in cold air intake manufacturing. An air bypass valve is a filtered spacer that is positioned more into the engine bay, between two connected pieces of the cold air intake assembly. This prevents hydro-locking by providing an alternate route for air to come in, thus eliminating the vacuum that causes water to be sucked in from a puddle. Foam filters are a simple piece of foam that is air permeable, and most have no valve. It is argued that this reduces power, but in actuality it provides more surface area for air to enter the engine when the driver presses the pedal. When driving at moderate speeds, the suction caused by the engine is not enough to activate the air bypass valve. Cloth filter bypass valves actually have a valve, air only enters if the valve is sucked open as result of the vacuum pressure caused by a blocked filter at the bottom of the intake. When it comes to cold air intakes this is the "best of both worlds"

See also

• Supercharger
• Turbocharger
• Booster engine
• Warm air intake
• Ram-air intake
• Air filter
• diffuser (automotive)