Originally Posted by Immortal
But what is with that 18000 ft limitation on all those diesels? Does anybody know?
Turbodiesel need much higher pressures to reach full rated power than classic Lycontinentals. For example, the MAP on Centurion 2.0 with full takeoff power is around 2.3 - 2.4 bar (~ 70"), while on Continental TSIO-360 the MAP is 40". As the altitude increases, the pressure drops and you can't sustain 70" for long, even in twin-turbo installations. Again, the critical altitude of Centurion 2.0 is around 6000ft (to achieve 100% load), while the TSIO-360 has it in the range of 12-13 thousand feet.
To simplify: you can get 200HP from an average normal aspirated Lycosaur, but you won't get it from a normal aspirated Diesel engine, unless you can swallow a substantial increase in size and weight. This is why virutally all cars use turbodiesel engines, not normal aspirated ones.