If you’re building a high-performance vehicle in New Zealand, you’ve probably come across the term AN fittings. These fittings are the backbone of performance hoses and motorsport plumbing, trusted by racers, engine builders, and enthusiasts alike. At anfittings.co.nz, we supply Speedflow fittings—precision-engineered connectors designed to keep your fluid systems safe, reliable, and leak-free.
What Does "AN" Mean?
The term AN stands for Army-Navy, a military specification originally developed during World War II. These fittings use a 37° flare design, making them superior to common 45° fittings found in industrial plumbing. The design ensures a secure, vibration-resistant seal—perfect for fuel systems, oil lines, coolant plumbing, and power steering setups in motorsport.
Thread Sizes and Dash System
AN fittings are sized using the dash (-) system, which relates to hose outer diameter in sixteenths of an inch:
-4AN → ¼" hose (common for fuel return lines)
-6AN → ⅜" hose (popular for fuel feed lines)
-10AN → ⅝" hose (ideal for oil cooler lines)
This universal sizing system makes it easy to match hoses, hose ends, and fittings for a reliable connection.
Why 37° Matters
In motorsport, leaks aren’t an option. The 37° flare sealing surface used in AN fittings provides superior performance under high pressure and constant vibration. That’s why you’ll see Speedflow fittings used on everything from drag cars and drift cars to marine and aviation applications. Mixing 37° AN fittings with other types like BSP, JIC, or NPT without adapters can cause dangerous failures—so stick with the correct standard.
Materials and Finishes
High-quality brands such as Speedflow use 6061-T6 aluminium for lightweight strength, with anodised finishes for corrosion resistance. Anodising also allows for easy colour coding—handy when you’re plumbing multiple systems (fuel, oil, coolant) and need to avoid cross-contamination. For extreme pressure or harsh environments, stainless steel AN fittings are also available.
Common Uses in Motorsport Plumbing
Fuel fittings – leak-free connections for petrol, E85, and ethanol fuels.
Oil fittings – withstands high temperature and pressure in engine and transmission systems.
Coolant hoses – lightweight and secure compared to traditional hose clamps.
Power steering fittings – built to handle heavy loads and constant pressure.
Installation Tips
1. Use proper AN spanners or soft jaws to protect the anodised finish.
2. Cut hoses clean and square for the best seal with your hose ends.
3. Pressure-test your system after installation to confirm everything is leak-free.
4. Don’t mix AN fittings with other thread standards unless using the correct adapter.
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Final Word
For anyone in New Zealand working on performance vehicles, AN fittings and hoses are the standard choice. With Speedflow fittings from anfittings.co.nz, you can be confident your fuel, oil, coolant, or power steering system will perform under pressure—whether it’s on the track, strip, or street.
If you’re looking for AN fittings in NZ, explore our full range today and build a fluid system you can rely on.