An engine apparatus is provided that includes an internal combustion engine and a cooling airflow control subsystem The cooling airflow control subsystem includes an airflow regulator having a first component comprising one or more passageways extending through the first component, and a second component comprising one or more passageways extending through the second component, the second component mounted adjacent the first component; and an actuator operably coupled to the airflow regulator to cause relative rotation between the first and second components when actuated so that the airflow regulator can be altered between: (1) a first state in which the first and second passageways are aligned a first extent to allow a first amount of cooling airflow to reach the engine; and (2) a second state in which the first and second passageways are aligned a second extent to allow a second amount of cooling airflow to reach the engine, the first amount being greater than the second amount.