In recent years, fuel consumption regulations are becoming more severe in every country in the world. Engine size reduction plus turbo is one of the solutions.Our turbo system has an intercooler which cools high temperature gas compressed by a turbocharger. The structure of the intercooler is a tank mounted on both sides of a heat exchanger. The tank connects to the heat exchanger and turbo system allowing EGR (Exhaust Gas Recirculation) gas through the heat exchanger in response to the tightening of exhaust gas regulations.Use of the LPL (Low Pressure Loop) system which refluxes EGR gas is expected to increase from now.Since EGR gas is characterized by high temperature, high pressure, and acidic condensed water, high fatigue strength at high temperature and acid resistivity is required. Therefore aluminum (AL) is generally applied for “intercooler tank” (hereafter referred to as “tank”).However, resinification is demanded from the viewpoint of material cost reduction, weight savings, minimizing of machining, and form flexibility.In consideration of mass-production, plastic parts are normally produced by injection molding of glass fiber (GF) reinforced plastics (GFRP). However, injection-molded products have GF orientation. Therefore, strength of transverse direction (TD) is about 50% of that of the molding direction (MD). This report shows plastic material was developed in which fatigue strength of TD is improved by about 40% by applying flat glass fiber, to be used instead of aluminum Al die-cast, and using LPL acidic condensed water.