Over the next ten years, one of the most important changes in engine technology will be the incorporation of plastic materials into the air induction manifold and the fuel distribution manifold. Engine performance will improve because of changes in the thermodynamic properties of the delivered fluids and fluid flow characteristics of the plastic materials. But, the most dramatic changes will be in the design of the overall engine, as engineers redesign engine components to take advantage of the less restrictive packaging requirements of composite material.Over the last couple of decades, resin suppliers have worked hard to engineer plastics that will perform under demanding engine conditions, conditions that a few years ago engineers felt could only be met with metallic materials. In the beginning, when plastics began to replace metal, the tendency was to use the metal designed part and duplicate the part in plastic, with some minor changes to accommodate for plastic. These were by far the most difficult situations for the plastic design engineer, for only after the plastic has performed in the application can the engineer redesign the part to maximize the properties of the plastic. 1The situation we are in today with air and fuel manifolds is not far from the original position of copying the metal design. Over the last decade, composite materials have been tested and developed to be used in these products. Metal designs have been and are being copied using plastic. The acceptance that plastic can do the job is here, and now the design engineer can finally start designing the part with the plastic properties in mind right from the beginning.