Actually, the base aircraft is the fairly common (in WW) Heinkel He-112, NOT the He-100 (which is being worked on by Heinkel, but is not ready for production at this time). Like the Iberian, Philipino, and Turkish aircraft, it's powered by a Jumo-211 rather than the historical Jumo-210. So no evaporative cooling (if you check last years German news, you'll find General Udet mentioning flying an He-113 with that system and commenting that it would need to be changed), just a normal liquid cooled inverted V-12.