The Cyclone was an upright inline six-cylinder water-cooled engine with a bore of 8.625 in (219.1 mm) and stroke of 12 in (300 mm) stroke, giving a displacement of 4,207 cu in (68,940 cm3).
Each cylinder had its own detachable head, with two spark plugs and four valves operated by push-rods driven by a single camshaft.
[1] The Cyclone was first run in 1922, producing 700 hp (522 kW) at 1,220 rpm.
Further development increased output to 850 hp (634 kW) at 1,350 rpm but could produce 950 hp (708 kW) at the same rpm with a larger carburettor.
[2] The Beardmore Typhoon was an inverted version of the Cyclone, with almost all parts being interchangeable between the two engines.