Engine designs require SX superalloy turbine blades and vanes which operate at higher gas and metal temperatures beyond 3% rhenium-containing SX alloys used in commercial and military flight engines. These castings must have excellent high temperature properties, good castability, solution heat treatment, oxidation/hot corrosion resistance, coating compatibility and phase stability. The highest strength 3rd generation SX superalloys (6-7% Re) have exhibited secondary reaction zone phase instability, low temperature internal oxidation/hot corrosion attack and difficulty in production solution heat treatment. Also, 3rd generation SX alloys have high density, a disadvantage in terms of weight and inertia for rotating parts, and high cost from elevated Re content. In response, Cannon-Muskegon has developed and characterized a new SX superalloy with improved properties over CMSX-4 alloy, competitive to 3rd generation alloys. CMSX-4 Plus alloy has been scaled to 5,000 lb production heat status for flight engine testing programs scheduled for 2016 and 2017.