A centrifugal compressor includes an impeller that defines an outside diameter and is rotatable about an axis to provide a flow of compressed fluid. A portion of the compressed fluid passes around the outside diameter to define a leakage flow. An extension extends from the impeller and includes a first seal portion that has an average diameter that is greater than or equal to about 50 percent of the outside diameter. A stationary seal ring includes a second seal portion that has a plurality of teeth. The second seal portion is disposed adjacent the first seal portion to define a seal that inhibits the passage of the leakage flow.
