Of these new stage designs, only the S-IV would ever be delivered, and not in the form that was drawn up in the Committee report. In order to meet development schedules a cluster of six Centaur engines were placed in the new stage to produce the "new" S-IV of roughly the same performance as the original four upgraded engines. A large number of small engines are less efficient and more problematic than a smaller number of large engines, and this made it a target for an early upgrade to a single J-2. The resulting stage, the S-IVB, improved performance so much that the Saturn was able to launch the Apollo CSM, proving invaluable during the Apollo Project.