C-Series Aluminum Intake Manifold, Ford 240/300 L6

The Offenhauser 6227C is an aluminum C-Series single-plane intake manifold engineered to enhance performance for Ford 240 and 300 cubic inch inline-six engines. Designed to bridge the gap between factory components and full-blown competition setups, this manifold aims to significantly improve torque delivery in the mid-to-upper RPM ranges, supporting a broad power band from 2,500 up to and beyond 7,000 RPM. Constructed from durable aluminum with a natural finish, the 6227C features a single-plane design optimized for airflow. It is specifically configured for square bore carburetors, offering versatility for various setups. While smaller applications can accommodate Holley 5200 or Weber 32/36 Series 2-barrel carburetors (with an adapter for Holley 2300 competition use), the six-cylinder, 4-barrel configuration is ideal for square bore Holley or Carter carburetors. For competitive applications, the emission-control provisions integrated into the manifold can be easily blocked off. The product description also highlights that when paired with headers and a cam, a Ford six engine equipped with this manifold (and potentially a Dual Port manifold) could see significant horsepower gains. One source indicates that dyno tests on a Ford six with the Offenhauser manifold, headers, and cam produced as much as 115 HP over the stock configuration. Another claim suggests that on a stock 240 or 300 CI engine, these manifolds can increase HP output by 50 HP.