[Dugie8]

In "general" terms, an airplane's service ceiling is usually more of a factor of maintaing cabin altitude around 8 to 10,000 feet. Be it either a limitation on the amount of bleed air the engine can supply to the cabin to maintain the desired "altitude" or a structual limitation on how much of a pressure differential the pressure vessel can tolerate

Another limitation could be O2 availability. To be able to make it from the highest altitude attainable to, and I may be wrong on the reg, 14,500 feet MSL there needs to be enough O2 on board to meet certain requirements.

There are other things like, service ceiling being where you can climbe at 100 fpm, and absolute ceiling being where you can climb at 50 fpm (I may have thos a little backwards). For the most part, when talking about service ceilings for turbo props and jets it is more a matter of "high dive" requirements, structural limits, etc than it is the engines ability to pull the airplane through the air.