The locomotive is powered by a single Ruston-Paxman-built power unit, which is a direct descendant of English Electric CSVT types; the closest relative to its engine is the 16CSVT, as used in the Class 50. However, there are numerous technical advances included in its design, including significantly uprated turbochargers, gear-driven camshafts in place of the timing chain used on Class 50s, and uprated cylinder heads, fuel pumps and injectors. The engine was nominally rated at , but was set at for rail use.