I don’t know about the numbers on a turbo, but I can tell you what my engine shop on the field told me about my 310. I have o-470s.
37000 a piece to do a complete overhaul. That is removing it from the airplane overhaul and reinstall. Poplar Grove Airmotive is the shop. A well respected engine shop.
My 310 costs me about 60% more to operate than the 4cylinder Mooney. This varies somewhat on stage length, but it certainly isn’t double.
As far as annual goes, you have one airframe and two engines. Anybody out there that has never owned a twin will always regurgitate the same horror stories. Not that horror stories can’t happen, but they can happen with any airplane. Truth be told, I lost a few hours of sleep worrying about 12 cylinders rather than just four.
As far as a twin not being any safer than a single, well that’s just silly. It’s another wives tale passed from generation to generation. The most dangerous time in a twin is second segment climb. The difference between a single and a twin in this position, is this: in the single, you’re going to crash, in the twin, you might crash. The real benefit comes in Cruise. If engine quits in a single, you’re landing in a field, if the engine quits in a twin, you’re gonna land at an airport. Same scenario at night, in a single, you’re gonna die, and a twin, you’re gonna live.
There is something to think about with the twin versus a single, and that is training/practice with engine-out procedures.
Realistically Speaking, engines rarely quit... but they do quit. There was one off of the Malibu in the engine shop just recently threw a rod through the side of the engine. Resulted in a crash and a fatality.
My NA 310 will easily climb into the teens at gross weight.
The Toga and Bonanza and Lance are great airplanes. I loved my Mooney, but flying back from Florida in my 310 late at night last time and not having to worry about picking a place to die if the engine quit was priceless.
Just my $.02
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