8AN to 4AN 1/4NPT Straight Male to Male

The REDHORSE PERFORMANCE 8AN to 4AN 1/4NPT Straight Male to Male adapter fitting is a precision hydraulic and fuel system component designed for applications requiring stepped connection between larger and smaller line diameters. This 816 Series straight adapter delivers reliable port-to-port transitions in high-pressure automotive, marine, and industrial fluid transfer systems where AN (Army-Navy) and NPT (National Pipe Thread) standards must interface.

Constructed from aluminum and finished in black anodized coating, this fitting combines corrosion resistance with weight efficiency—critical for performance vehicles and marine equipment exposed to moisture and salt air. The 8AN male connection accommodates larger-diameter hoses and hard lines, while the 1/4-inch NPT male port allows integration with industry-standard threaded manifolds, gauges, and component ports. The straight configuration eliminates flow restrictions common to 90-degree or 45-degree bends, maintaining optimal pressure integrity in closed-loop fuel injection, turbo coolant circuits, and transmission cooling lines.

This adapter serves race-car builders, marine technicians, and engine rebuilders who need to consolidate multiple outlet ports into single delivery lines without sacrificing flow efficiency or system reliability. Whether routing fuel from a surge tank to a carbureted engine, stepping down coolant lines on an LS swap, or managing transmission feed circuits on offshore fishing vessels, this fitting eliminates the need for bulky adapter manifolds and reduces component count. The compact 2.75 x 3.75-inch footprint and 0.06-pound weight make installation straightforward in tight engine bays and under-deck spaces.

REDHORSE fittings are manufactured to SAE J518 AN standards and designed for pressures common to modern fuel systems, forced induction cooling, and fluid transfer applications. When selecting stepped adapters, confirm that both the 8AN and 1/4NPT threads match your system specifications and that thread sealant (PTFE tape or approved thread compound) is applied to the NPT male port to prevent weeping.