The use of injection molded nylon by automakers in large under-hood applications may get a boost from a technology initiative between Trexel Inc., which licenses the MuCell microcellular foam process, and resin supplier Rhodia Polyamide. The companies are adapting their respective technologies to permit the molding of such components as air-intake manifolds and rocker covers that combine the performance and economic benefits of microcellular foam cores with the finish of appearance parts, a combination that has been difficult to achieve.