Collector Gaskets - Holley Performance Products

Collector Gaskets Features

Puts an end to exhaust leaks between the header and collector flanges forever
Made of a heat-resistant, tear-resistant compressed-fiber laminate
Top-of-the-line Ultra-Seal Collector Gaskets are made of a special high-temperature graphite-impregnated facing and a steel-expanded metal core that conforms to warped flanges
Pulls heat away from the cylinder head
Maximum heat resistance and thermal conductivity
Won't crack or deteriorate from excessive heat or pressure

Describes the outside diameter of the collector outlet. The larger a collector diameter is, the higher its mass flow potential will be with an inverse effect on velocity. Maintaining velocity is critical to supporting low-mid RPM performance and should be an important point to consider when choosing header collector size. For most V8 equipped vehicles with an exhaust system after the headers, 3" collectors are the limit for practical collector diameters. Dedicated drag race vehicles equipped with open headers can benefit from running larger (up to 4.5") and longer (between 16"-20") collectors than typically used on headers developed to be connected to an exhaust system.