#6 Flare Union Black

The #6 Flare Union Black (XRP981506BB) is a precision hydraulic fitting designed for high-performance fuel and coolant line applications in modified and race vehicles. As someone who has rebuilt countless engine bays and tuned fuel delivery systems, I can tell you that proper fittings are foundational to reliability—especially when running elevated boost pressures or aggressive fuel mapping. This flare union serves as a leak-free connection point in fuel systems, transmission coolers, and engine cooling circuits where vibration and thermal cycling demand absolute integrity.

The #6 size designation refers to a 3/8-inch tube diameter—a common standard in modern fuel rails and coolant manifolds. The flare union features a 45-degree flared end (SAE J512 specification) that creates a metal-to-metal seal without requiring ferrules or additional compression hardware. The black anodized or powder-coated finish provides corrosion resistance in engine bay environments while maintaining a professional appearance. At just 0.06 lbs and compact overall dimensions, this fitting adds negligible weight to your fuel or cooling system while guaranteeing reusable connections that won't weep under pressure cycles—critical when upgrading fuel injectors, installing auxiliary coolers, or transitioning to braided stainless steel lines.

Engine builders, turbo installers, and fuel system tuners gravitate toward #6 flare unions because they eliminate the risk of pinhole leaks that plague compression fittings in high-frequency vibration environments. Whether you're plumbing a direct-injection fuel rail upgrade, routing a transmission cooler on a supercharged build, or replacing seized fittings in a classic restoration, this black flare union delivers OEM-grade reliability. Installation requires only a standard wrench—hand-tight plus one-quarter turn is typical—making integration straightforward during any fuel or cooling system refresh.