High Quality Content by WIKIPEDIA articles! The Rolls-Royce R was a British aero engine designed and built specifically for air racing purposes by Rolls-Royce Limited. Nineteen R engines were assembled in a limited production run between 1929 and 1931. Developed from the Rolls-Royce Buzzard, it was a 37-litre (2,240 cu in) capacity, supercharged V-12 capable of producing just under 2,800 horsepower (2,090 kW), and weighed 1,640 pounds (770 kg). Factory testing initially revealed mechanical failures that were reduced by the use of redesigned components, greatly improving reliability.