Firewall Junction 3 Big 2 Small Hole

The Firewall Junction 3 Big 2 Small Hole is a precision aluminum manifold block engineered for custom engine bay plumbing and pneumatic systems in race and performance applications. This QUICKCAR RACING PRODUCTS component consolidates multiple inlet and outlet ports into a single, compact junction point, eliminating the need for scattered fittings and reducing complexity in high-performance engine builds. Whether you're routing fuel lines, vacuum systems, coolant passages, or compressed air circuits, this manifold serves as the central hub where multiple fluid or gas paths converge and distribute efficiently.

Constructed from lightweight aluminum and finished in durable black anodizing, the Firewall Junction 3 Big 2 Small Hole features three ports with 1/8 inch NPT (National Pipe Tapered) threads—typically sized for higher-volume flow lines—and two open ports ready for secondary fittings or caps. The NPT threaded configuration ensures leak-free connections with standard automotive hose barbs, adapters, and male fittings, while the anodized surface resists corrosion and oxidation in harsh engine compartment environments. At just 0.27 lbs with compact dimensions (4.05 × 0.85 × 7.05 inches), it installs cleanly behind the firewall or in tight intake manifold spaces without adding significant weight to your vehicle's unsprung mass.

This manifold is ideal for street rod builders, drag racers, and engine swap enthusiasts who demand clean, organized plumbing runs and require multiple simultaneous connections without bulky adapter clusters. It's equally valuable for vacuum distribution in forced-induction setups, coolant bypass routing in engine conversions, or fuel system configurations where a central junction simplifies line management and reduces potential leak points. Installation requires only standard wrenches or adjustable spanners; thread sealant (PTFE tape or pipe dope) on NPT connections ensures reliable, vibration-resistant seals for years of reliable performance.