User blog comment:Bovell/Treyarch begins staffing for next project. MW3 announcement next month./@comment-120.28.64.77-20110331055726/@comment-2126624-20110401153210

well the simple way BO engine is WAW engine upgraded WAW engine is a modified COD4 engine COD4 engine is a upgraded COD2 engine COD2 engine is an upgraded COD1 engine and COD1 engine is IDtech 3 engine so in conclusion new games old engine upgraded