K&N Engineering

K&N Engineering, Inc. is a manufacturer of performance air filters, air intake systems, oil filters, performance parts and other related products. K&N manufactures over 6,000 parts for various makes and models of cars, trucks, SUVs, motorcycles, ATVs, industrial applications and more. Founded in 1964, K&N is headquartered in Riverside, California, in a complex of 10 buildings comprising nearly 400,000 square feet. K&N also operates facilities in England and the Netherlands.

History

K&N was founded by Ken Johnson and Norm McDonald in 1964. The name K&N came from the first letters in the founders' first names. Johnson and McDonald sold motorcycles and motorcycle parts and supported a K&N factory race team. Air filters soon became the primary focus of the company. In the late 1980s K&N introduced a bolt-on performance air intake kit to replace the factory airbox and air filter. K&N also released a line of Wrench-Off oil filters. K&N has maintained very active involvement in racing and motorsports throughout its history, including the NASCAR Pro Series East and West, and the King of the West 410 Sprint Car Series.

Mass flow sensor

A mass (air) flow sensor (MAF) is used to find out the mass flowrate of air entering a fuel-injected internal combustion engine.

The air mass information is necessary for the engine control unit (ECU) to balance and deliver the correct fuel mass to the engine. Air changes its density as it expands and contracts with temperature and pressure. In automotive applications, air density varies with the ambient temperature, altitude and the use of forced induction, which means that mass flow sensors are more appropriate than volumetric flow sensors for determining the quantity of intake air in each cylinder. (See stoichiometry and ideal gas law.)

There are two common types of mass airflow sensors in use on automotive engines. These are the vane meter and the hot wire. Neither design employs technology that measures air mass directly. However, with additional sensors and inputs, an engine's ECU can determine the mass flowrate of intake air.

Both approaches are used almost exclusively on electronic fuel injection (EFI) engines. Both sensor designs output a 0.0–5.0 volt or a pulse-width modulation (PWM) signal that is proportional to the air mass flow rate, and both sensors have an intake air temperature (IAT) sensor incorporated into their housings for most post OBDII vehicles. Vehicles prior to 1996 could have MAF without an IAT. An example is 1994 Infiniti Q45.