6AN to 4AN 1/4NPT Straight Male to Male

The 6AN to 4AN 1/4NPT Straight Male to Male fitting by REDHORSE PERFORMANCE is a critical adapter for custom fuel, coolant, and hydraulic line routing in high-performance automotive builds. This reducer fitting bridges two different AN port sizes while incorporating 1/4" NPT male threading, making it indispensable for engine bay plumbing where line consolidation or system reconfiguration is required. Whether you're tuning a turbocharged engine, installing an aftermarket fuel system, or integrating a custom cooling loop, this compact adapter ensures leak-free connections between incompatible hose sizes without compromising flow integrity.

Constructed with precision machining, the straight male-to-male design eliminates unnecessary bends and reduces turbulence in fuel delivery or coolant circulation systems. The 6AN inlet accepts larger diameter hose (typically -6 rated) while the 4AN outlet reduces to smaller hose capacity (-4 rated), allowing mechanics to step down system pressure safely or adapt legacy plumbing to modern components. The NPT port adds versatility for gauge installation, drain lines, or vacuum-operated fuel regulators. All REDHORSE fittings meet automotive industry standards for thread concentricity and surface finish, critical for vibration resistance and corrosion prevention in engine compartments exposed to fuel, oil, and thermal cycling.

This adapter serves professional mechanics, engine builders, and dedicated enthusiasts upgrading fuel systems, turbocharger plumbing, or custom cooling circuits on street and track vehicles. Its compact 2.75-inch length and lightweight 0.05 lbs design fit tight engine bays without weight penalty, making it ideal for weight-sensitive platforms. Confirm hose barb sizes and NPT thread compatibility with your existing fuel lines and components before installation; proper PTFE tape application on NPT connections and torque-to-spec tightening of AN fittings ensure lasting reliability under pressure and temperature extremes.