A turbomachine that includes a radial-flow impeller and one or more of a variety of features that enhance the performance of machinery in which the turbomachine is used. For example, when the turbomachine is used in a dynamometer, the features enhance the useful shaft horsepower range of the dynamometer. One of the features is a variable-restriction intake that allows for adjusting flow rate to the impeller. Other features include a unique impeller shroud and a shroud guide each movable relative to the impeller. Yet another feature is an exhaust diffuser that facilitates an increase in the range of shaft power and the reduction of deleterious vibration and noise. The turbomachine can also include a unique impeller blade configuration that cooperates with the adjustable intake and the exhaust diffuser to enhance flow through the turbomachine.