This work presents a study of manufacture and assembly costs reduction in a diesel engine model manufactured in an industry situated in Curitiba that intends to make this engine economically feasible. The study presents a brief literature review about product development and technological resources to support product design, emphasizing a review about the DFMA (Design for Manufacturing and Assembly) method. The paper presents a detailed description of how delimited the most critical subsystem of the engine was, considering the cost and the application of DFMA guidelines for the delimited subsystem. The results show an impact in the cost reduction of the subsystem chosen of 1.8% and in the entire engine of 0.7%.