The short ram air intake is a form of aftermarket

Aftermarket (automotive)

The automotive aftermarket is the secondary market of the automotive industry, concerned with the manufacturing, remanufacturing, distribution, retailing, and installation of all vehicle parts, chemicals, tools, equipment and accessories for light and heavy vehicles, after the sale of the...

 air intake for automobile

Automobile

An automobile, autocar, motor car or car is a wheeled motor vehicle used for transporting passengers, which also carries its own engine or motor...

s with internal combustion engine

Internal combustion engine

The internal combustion engine is an engine in which the combustion of a fuel occurs with an oxidizer in a combustion chamber. In an internal combustion engine, the expansion of the high-temperature and high -pressure gases produced by combustion apply direct force to some component of the engine...

s.

It basically replaces the OEM

Original Equipment Manufacturer

An original equipment manufacturer, or OEM, manufactures products or components that are purchased by a company and retailed under that purchasing company's brand name. OEM refers to the company that originally manufactured the product. When referring to automotive parts, OEM designates a...

 air intake with a short metal pipe and a conical air filter

Air filter

A particulate air filter is a device composed of fibrous materials which removes solid particulates such as dust, pollen, mold, and bacteria from the air. A chemical air filter consists of an absorbent or catalyst for the removal of airborne molecular contaminants such as volatile organic compounds...

 inside the engine bay. A significant increase in intake air volume will only occur in an engine where the factory intake piping was restrictive.

There is still some open debate on this issue, but some believe that a problem with short ram air intakes is that the air entering the intake is at a higher temperature due to the proximity of the engine, which may reduce some power. This may be partially offset by an increase in the volume of air entering the engine. To counter intake heat problems, many short ram intakes include some form of heat shield. Moving the intake inlet port further away from the engine block will also help to alleviate the problem and some users use a cold air intake

Cold air intake

A cold air intake is an aftermarket assembly of parts used to bring relatively cool air into a car's internal-combustion engine.Most vehicles manufactured since the mid-1970s have thermostatic air intake systems that regulate the temperature of the air entering the engine's intake tract, providing...

 where the inlet air is at or close to ambient temperature. However, others claim that Short Ram Intakes (SRIs) or similar Warm Air Intakes (WAIs) offer benefits over Cold Air Intakes (CAIs) which include better MPG due to a more complete burning of fuel. Users with forced induction

Forced induction

Forced induction is the process of compressing air on the intake of an internal combustion engine . A forced induction engine uses a gas compressor to increase the pressure, temperature and density of the air...

 engines often opt for short ram intakes because compressors

Gas compressor

A gas compressor is a mechanical device that increases the pressure of a gas by reducing its volume.Compressors are similar to pumps: both increase the pressure on a fluid and both can transport the fluid through a pipe. As gases are compressible, the compressor also reduces the volume of a gas...

 adjacent to the engine, especially turbocharger

Turbocharger

A turbocharger, or turbo , from the Greek "τύρβη" is a centrifugal compressor powered by a turbine that is driven by an engine's exhaust gases. Its benefit lies with the compressor increasing the mass of air entering the engine , thereby resulting in greater performance...

s, heat the incoming air and negate much of the benefits of a cold air intake. Additional problems can result from using a short ram intake in cars utilizing a mass airflow sensor though most of today's sensors automatically adjust without issue. Turbulence

Turbulence

In fluid dynamics, turbulence or turbulent flow is a flow regime characterized by chaotic and stochastic property changes. This includes low momentum diffusion, high momentum convection, and rapid variation of pressure and velocity in space and time...

in the intake airflow produced by the filter or piping, or a change in intake diameter at the point where the airflow is measured can produce inaccurate airflow readings. The error in airflow then translates to an error in the amount of added fuel. In the worst case, the air/fuel ratio can run lean, causing detonation and possibly engine failure although the airflow sensor will generally detect and correct the throttle to compensate for the warmer air. This can also be solved by modifying/elongating the intake piping, replacing the airflow meter, or by replacing/remapping the engine control computer to provide the correct amount of fuel for the intake airflow at all engine speeds.

A harmless but noticeable result of using a short ram air intake is an increase in intake noise, which may manifest as a sucking sound, and the loss of any silencing properties that the factory intake had.