According to Deutz, the max permissable oil temp for an Air-Diesel  is 257°F. Max permissable temps for the cylinder fins is 338°F. To keep water from boiling at that temp you will need a minimum of 115 PSI. Good luck with designing a radiator and plumbing system to handle that and you'll need an extra measure of luck to deal with a superheated steam explosion that will occur when a hose or radiator bursts. Of course, you will need even higher pressures to keep the hot spots along the cylinder liners from boiling and really causing a cavitation wreck.
While high operating temps are great for efficiency, you can imagine the amount of NOx the high temps in a Deutz would cause. With the advent of exhaust after-treatment solutions like SCR, we may indeed start to see some air-diesels begin to appear in trucks again, like was common in Europe in the past.