Performance Perspectives

Motor, Nov 2007 by Mavrigian, Mike

You may be asked to install AN plumbing for its performance characteristics or eye appeal. Either way, working with these components requires special tools and techniques.

High-performance plumbing systems are a must for any race engine, They're also commonly employed on high-performance and custom-car street applications, for their performance value as well as for cosmetics. High-performance plumbing utilizes threaded connections as opposed to hoses that slip on and are secured with a compression clamp. This type of threaded connection plumbing is commonly referred to as AN plumbing.

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AN sizes (also called dash AN and written as -AN) originated witìi military applications, to handle fuel, oil, coolant and hydraulic plumbing on aircraft, ships, tanks, etc. (AN actually stands for Army/Navy.) These plumbing hose assemblies feature a tough, braided/reinforced hose, coupled with threaded connections that feature a 37° sealing seat. They provide a tough, leakproof plumbing arrangement that can't accidentally pop off due to vibration or extreme pressure. Following WWII, racers began to adapt these hoses and connections for their own use. Today, racers (who need the durability of these systems) and street perfor1 mance enthusiasts (who want the race car look) commonly use AN hose systems.

So, we may refer to these hoses, hose ends and fittings sizes with the word (or symbol) dash, or by the terms AiV or -AN. These are simply different terms for the same thing. For example, "I plumbed my fuel system with dash 8 hose"; or "I used dash 8 AN hose for my carburetor feed."

AN hose sizing is based on single- and double-digit identification numbers to designate die hose theoretical inside diameter (I.D.). The dash number refers to the hose inside diameter, in increments of [fraction one-sixtenth] in. For example, a -10 size translates to [fraction ten-sixteeth] in. (or 5/8 in.) I.D. An easy way to understand dash sizes is to think in terms of [fraction one-sixtenth]-in, increments. A -6 means that the inside diameter is [fraction six-sixtenth] in. A -8 size is [fraction eight-sixtenth] in. I.D. The larger the number, the larger the hose diameter.

AN hose assemblies require three primary items: AN hose, AN hose ends and AN fittings or adapters. The hose will feature either a stainlesssteel braided outer cover or a braided reinforced fiber cover. The hose end is the plumbing fixture that attaches direcdy to the bare hose and, in effect, becomes part of the hose. The hose end will feature a female threaded port with a 37° female seat. It completes its connection by threading onto an AN male fitting or adapter, which is threaded into a component (engine block, cylinder head, intake manifold, dry-sump pump, etc.). During service, the fitting/adapter stays with the component, and die hose, with its hose ends, is the item that's removed.

Hose End and Adapter Colors

The so-called standard of the AN hose world, at least for automotive performance applications, are red and blue anodized finishes. While aluminum fittings and adapters are usually solid blue (sometimes red), two-piece hose ends are generally blue and red. Color shades and finishes will vary among makers. So if it's important to your customer that everything looks matched, it's best to stick with one particular manufacturer's hose ends and fittings.

Remember, anodizing is not a coating. It's actually a controlled oxidation process used to protect the finish of an alloy, to allow the use of a color dye and/or to harden the alloy surface. A dull, nongloss appearance is quite normal. If a higher gloss is desired, manufacturers can polish the aluminum beforehand, and they even have the option of using a gloss clear anodizing. The point is to look at the various makers' offerings, and if appearance is critical, decide what color and finish is preferred, then stick with that one manufacturer's hardware.

Hose Ends

Hose ends attach direcdy to the hose and provide a high-pressure seal. The hose end is a two-piece arrangement consisting of a socket, which slips over the end of the hose and features a female threaded opening, and a male/female tube assembly. The male/female piece features a male threaded nipple that threads into the hose end socket. The female (exposed) end is then ready to tiiread onto a male fitting at the desired installation location.

Note: While this is the most common configuration, not all assembled hose ends feature female threads. Some makers offer special male threaded ends that fit into female fittings.

Hose ends not only allow hose connection and sealing but because they're available in various shapes, you can obtain installed angles necessary for clearance and preferred routing. Hose ends are available in angles of 30°, 45°, 90°, 120°, 150° and even 180°. Angled hose ends are offered in standard-profile and low-profile versions. Standard-profile hose ends feature a tube neck, lowprofile hose ends a forged or machined neck that shortens the hose end's distance from the fitting connection to the bend. Low-profile is a good choice where space is at a premium.

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Performance Perspectives

Motor, Nov 2007 by Mavrigian, Mike

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