manx nortons also played a significant role in the development of post war car racing. at the end of 1950, the english national 500 cc regulations were adopted as the new formula 3. the jap speedway engine had dominated the category initially but the manx was capable of producing significantly more power and became the engine of choice. many complete motorcycles were bought in order to strip the engine for 500 cc car racing, as norton would not sell separate engines.