This paper presents a case study of the development of a new water cooled DOHC cylinder head. This specific head represents the highest geometric complexity, including multiple core cavity structures, in cylinder heads. The goal of this study was to verify the possibility of a paradigm shift in engine development, in which tooling design and production are postponed until after dynamometer testing of the engine is completed. This paradigm shift becomes possible with the use of Direct Shell Production Casting a rapid manufacturing process which makes traditional casting obsolete.Using Direct Shell Production Casting (DSPC®) to produce the prototype cylinder heads and blocks in aluminum and ductile iron enabled the development team to completely eliminate the need for temporary tooling. DSPC works directly off of a CAD file to create the actual ceramic casting molds, complete with integral cores. This results in functional cylinder heads and blocks, that can be tested on a dynamometer under actual conditions and then changed or approved. Changes simply become adjustments to the CAD file, and then a new part can be cast immediately. This case study also verified the DSPC process' ability to accurately simulate the casting process and verify the gating design, direction and rate of solidification and other casting parameters. The results of the casting process verification have been essential in designing the production tooling (permanent molds and core boxes) correctly on the first attempt. In this case, DSPC was used to cast net shape production tooling from the same CAD file as the approved cast part.DSPC eliminates the time and cost associated with multiple iterations using more traditional prototyping and tool creation methods. The results of this case study strongly confirm that by combining DSPC and conventional casting practices long lead times, product development costs, and production tooling costs are substantially reduced.