| CPC F28F 1/26 (2013.01) [B22D 27/045 (2013.01)] | 11 Claims |

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1. A cast part comprising:
an outermost wall; and
a first inner wall, a second inner wall, and a third inner wall which define at least four internal passages, wherein any cross-sectional circular area spanning at least a portion of each of said four internal passages includes a ratio of interior empty space to inner wall space that is greater than zero and no greater than 3.6.
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