AN-fittings are fittings made to connect hoses and metal tubing. AN stands for Army and Navy as the product dates back to World War II. AN-fittings are widely used in motorsports, as the fittings are much more rigid than for example a regular hose clamp. In motorsport and racing, the use of hose clamps in high-pressure systems is prohibited.

The AN-fitting is always made in steel or aluminum and has threaded ends, which makes the coupling so durable. In some fuel systems and other high-pressure systems in a car, the pressure sometimes exceeds 10 bar. In these systems, the pressure could easily break off a hose clamp, hence the use of An-fittings.

If you are upgrading your car with a high-pressure fuel pump, or maybe installs a turbo which needs a high-pressure oil feed, you should think about investing in an-fittings. As a fuel or oil cut easily could damage your engine or turbo.

How to find the right AN-fitting

The sizing of AN-fittings can be a bit tricky to understand. When buying the fitting the products are often referred to as for example AN-4 fitting. The number in the name is the external diameter of the coupling. The number refers to parts of 16th of an inch. For example, an AN-8 fitting is 8/16th of an inch, so 1/2 inch. The most common sizes and uses when it comes to race cars are;

  • An-3 fittings are most commonly used for brake lines
  • AN-4 for fuel hoses
  • AN-6 for fuel or coolant hoses
  • AN-8 for coolant and oil
  • AN-10 and 12 are mostly used for coolant or vent hoses

If you’re unsure which coupling is the right one for you, you can always contact a reseller. They are usually very helpful in finding out what size you need.