Investigations using laboratory test benches are the most common way to find the technological solutions that will increase the efficiency of internal combustion engines and curtail their emissions. In addition, the collected experimental data are used by the CFD community to develop engine models that reduce the time-to-market. This paper describes the steps made to increase the reliability of engine experiments performed in a heavy-duty natural-gas spark-ignition engine test-cell such as the design of the control and data acquisition system based on Modbus TCP communication protocol. Specifically, new sensors and a new dynamometer controller were installed. The operation of the improved test bench was investigated at several operating conditions, with data obtained at both high- and low-sampling rates. The results indicated a stable test bench operation.