"Lucania" and "Campania" had the largest triple-expansion engines ever fitted to a Cunard ship. These engines were also the largest in the world at the time, and still rank today amongst the largest of the type ever constructed. They represent the limits of development for this kind of technology, which was superseded a few years later by turbine technology. In height, the engines were 47 feet, reaching from the double-bottom floor of the engine room almost to the top of the superstructure – over five decks. Each engine had five cylinders. There were two high-pressure cylinders, each measuring in diameter; one intermediate-pressure cylinder measuring in diameter; and two low-pressure cylinders, each measuring in diameter. They operated with a stroke of . Steam was raised from 12 double-ended scotch boilers, each measuring in diameter and having eight furnaces. There was also one single-ended boiler for auxiliary machinery and one, smaller, donkey boiler. Boiler pressure was 165 lb, and enabled the engines to produce , which translated to an average speed of , and a record speed of knots. Normal operating speed for the engines was about 79 rpm.