AN Fitting
What Are AN Fittings?
AN fittings — short for Army-Navy fittings — are a precision connector standard with roots in U.S. military engineering. AN fittings are defined by their distinctive 37-degree flare seating surface, which creates a reliable metal-to-metal seal without relying on thread tape, sealant compounds, or O-rings that can degrade when exposed to ethanol-blended fuels or high operating temperatures. Today, they are the go-to connection standard across motorsport, road racing, and performance street builds.
Why AN Fittings Matter in Fuel Injection Systems
In a high-performance fuel injection system, every connection in the fuel path — from the tank to the pump, filter, regulator, and fuel rail — must hold pressure reliably under demanding conditions. Standard rubber hoses and hose clamps simply cannot match the sealing integrity or reusability of a properly assembled AN fitting. AN fittings use a precision 37-degree flare that forms a tight, leak-free connection between fuel lines and components like fuel pumps, rails, and pressure regulators.
AN fitting sizes are expressed as a dash number (e.g., -6AN, -8AN, -10AN), with each size corresponding to a specific hose inner diameter measured in 1/16-inch increments. Choosing the right size matters: a -6AN fitting suits smaller fuel lines and moderate-flow applications, while -8AN or -10AN fittings are typically required for high-flow builds supporting serious power levels. Fittings are also available in straight, 45-degree, 90-degree, and 180-degree configurations to accommodate tight engine bays and custom routing without inducing stress or kinking the fuel line.
Material selection is equally important. Most performance AN fittings are CNC-machined from 6061-T6 aluminum for a lightweight, corrosion-resistant connection, while stainless steel options offer additional durability in harsh environments.
Key Considerations When Shopping AN Fittings
- Size compatibility: Always match the AN dash size to both your hose inner diameter and the port size of the component you are connecting to.
- Hose type: AN fittings are designed to work with braided stainless steel or PTFE-lined hoses — not standard rubber hose. PTFE-specific fittings use a different collar design than rubber hose ends and are not interchangeable.
- Thread standards: AN fittings use straight threads and a 37-degree flare to seal. They are not compatible with NPT (tapered pipe thread) ports without an appropriate adapter.
- Angle selection: Use straight fittings where space allows; opt for 45- or 90-degree versions near bulkheads, firewalls, or tight corners to prevent line stress.
- Fuel compatibility: Confirm fittings and associated seals are rated for your fuel type, especially ethanol (E85) or methanol blends.
Top Brands for AN Fittings
RADIUM Engineering is widely recognized as a leader in high-performance fuel system components. RADIUM stands out in the AN fitting category with their unique swiveling fitting designs, which simplify installation in tight spaces, and their complete ecosystem of adapters, hose ends, and bulkhead fittings engineered specifically for performance fuel systems.
DeatschWerks brings the same engineering rigor to their AN fitting lineup that has made them a trusted name in high-performance fuel pumps and injectors. Their fittings are designed to integrate seamlessly into complete fuel system builds, making them a natural choice for enthusiasts sourcing multiple fuel system components from a single supplier.
Red Horse Performance has earned a strong reputation in professional motorsport for producing high-quality AN fittings and plumbing components built to withstand the rigors of racing. Their focused catalog and race-proven reliability make them a respected choice among competitors and serious builders.
Fragola Performance Systems offers a broad range of AN fittings and adapters tailored to both racing and high-performance street applications. Fragola's extensive selection of configurations and sizes makes them a versatile option when building or modifying a custom fuel system.
Vibrant rounds out the category with AN fittings known for precise machining and broad application coverage. Vibrant's fittings are a popular choice among fabricators and enthusiasts looking for well-made components across a wide range of sizes and angles.