text: Three models were provided with varied settings for its two-speed supercharger, tuned for different low- versus high-altitude performance. The first prototype aircraft powered by the 211A appeared in late 1937. Development of the 211 continued with the 211B being released in 1938, with a slightly increased maximum RPM of 2,400 which boosted power to 1200 PS (1184 HP). The later 211C and 211D differed primarily in the propeller gear ratios and other features.
  The competing DB 600 design was generally similar but lacked the direct injection system. When the RLM expressed their opinion that all future engines include this feature, Daimler responded by introducing the DB 601 in late 1937.
  A major upgrade was started by Junkers in 1940 adapting the Jumo 211 with a pressurized cooling system. Under pressure, the boiling point of water increases, allowing the engine to run hotter. This, in turn, allows a given amount of cooling fluid to carry away more energy. As a result, the engine could run at higher power settings with a smaller radiator system. The resulting 211E proved to be able to run at much higher power settings without overheating, so it was quickly followed by the 211F which included a strengthened crankshaft and a more efficient supercharger. Running at 2,600 RPM the 211F delivered  and the 211J (a 211F with intercooler) . Further improvements to this basic line led to the  211N and  211P in 1943, they were equivalent to the 211F/J but with slight boost increases and running at up to 2,700 rpm. Continued development of the 211 line evolved into the Jumo 213.