Merge Collector 2-3/8in Primaries 4-1/2in Outlet

The Stainless Works Merge Collector 2-3/8in Primaries 4-1/2in Outlet is a premium slip-on exhaust merge collector designed for high-performance engine builders and restoration enthusiasts seeking to consolidate four primary runners into a single larger diameter outlet. This 4-into-1 merge collector represents a critical step in custom exhaust manifold construction, allowing independent tuning of primary pipe sizing while maintaining flow efficiency through the collector junction.

Built from stainless steel in natural finish, the collector features 2.375-inch primary inlet ports and a 4.5-inch outlet diameter. This size transition is engineered to manage the velocity of exhaust gas from four independent primaries, promoting scavenging efficiency while minimizing turbulence at the junction. The slip-on design allows for custom primary tube connection, making this collector compatible with various header configurations. Weighing 3.21 pounds and measuring 11.55 inches in length, the collector fits within standard engine bay constraints while delivering the flow characteristics necessary for naturally aspirated and mild forced-induction applications.

This merge collector serves enthusiasts fabricating custom long-tube headers, street rods, and performance engine swaps where factory exhaust manifolds are being replaced. Engine builders rely on merge collectors to transition from optimized primary runner sizes to a unified outlet, which then feeds into a secondary pipe, muffler, or turbocharger inlet. Stainless steel construction resists corrosion from repeated heat cycles and moisture exposure, extending the service life of the assembly in both street and track environments.

Merge collectors are essential components in custom exhaust systems because they consolidate flow from separate primaries while maintaining scavenging pulse characteristics. The 4-1 configuration is common in four-cylinder and V6 applications, as well as some V8 platforms where sequential exhaust timing is desired. Proper collector sizing directly influences engine breathing efficiency, which impacts power output across the RPM range.