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What are AN fittings and AN hose?

Many fuel, oil, air, and water systems are built with AN-fittings, but what is it, and how does it work?

Here we show simply and clearly which parts are available, and how they are connected and mounted to different products. With this information, you learn to choose the right AN fittings and hose to assemble them correctly.

The different categories we go through are:

  1. Hose and hose ends
  2. Adapters
  3. Installation
  4. Different types of hose and hose ends

The AN system works as Lego pieces. You use the different building blocks to connect two parts.
Oil cooler <-> engine
Water and oil:
Turbo <-> engine
Fuel cell <-> engine
Luft: Wastegate <-> Turbo


1. Hose and hose ends

AN hose is made to have hose ends on each end. These fittings are easily assembled without special tools. When fittings are mounted on the hose, there is a UNF / AN thread at each end. Now we have assembled AN hose.

We now use adapters to connect this AN hose to a turbo, engine, radiator, fuel pump, catch tank, or anything else that needs air, water, oil, or fuel.


2. Adapters

When the AN hose is assembled, you use different adapters to connect products/parts. AN-adapters have a thread at each end.
  • AN-system UNF thread with 37 degrees cone at one end to fit hose ends.
  • At the other end, select the desired thread you want to connect.

3. Installation

Example of a turbo oil line:

You want to install a hose for the turbocharger oil supply that has about 5mm inner diameter.

The turbo oil inlet has a 1/4" NPT thread.

The engine outlet thread is M14x1,5

The question to ask is:

  1. What media should we tranport?
    AN hose with rubber core will be well suited.
  2. What hose size should we use?
    about 5mm
    Then a AN4 hose with 5,5mm inner diameter will work well.
  3. What hose ends should we use?
    These hose ends will fit in each end of the hose.
  4. What adapters should we use on the turbo side?
    1/4" NPT
    Then we pick a 1/4" NPT to AN4 adapter (1/4" NPT thread in one and and AN4 thread in the other end.)
  5. What adapters should we use on the engine side?
    Then we pick a  M14x1,5 to AN4 adapter (M14x1,5 thread in one and and AN4 thread in the other end.)

The recipe for parts will be as follows:

1x AN4 hose with rubber core
2x AN4 hose ends to fit AN4 hose with rubber
1x Adapter to turbo 1/4" NPT -> AN4
1x Adapter to engine M14x1,5 -> AN4


4. Different types of hose and hose ends

Depending on the media used, different types of hose are suitable

  • Hose with rubber core for oil, water and air.
  • PTFE hose with plastic core for fuel
  • Push-On hose completely in rubber for oil, air and water (Also fuel if hose clamp must be used)
The three different types of hose also have three different types of hose ends to fit the hose.