A mechanical drive train for testing a full scale compressor rig is disclosed. The drive train can include an electric motor, a gear box, and a gas turbine. The compressor rig is coupled to the drive train between the gear box and gas turbine. The drive train can further include a torque converter for transferring torque from the electric motor to the compressor rig. The drive train is configured to test a full scale compressor rig over the entire speed and load operating range, allowing for full compressor mapping from choke to stall at full load, part load (power turn down) and partial speed conditions. The drive train can also be used to test a compressor rig or gas turbine over the full range of operability for the compressor rig or gas turbine without having to connect the gas turbine to the power grid at the power generation site.