Ronnie,

I'd
guess that even at engine overhaul time, econmics
would be vastly in favor of overhauling the old engines
as compared to replacing them with diesels.


Of course it will be more expensive. After all, you're getting a brand
new engine. Apart from that, a lot depends. The way Thielert does it
here, they guarantee you 2400 hours (or, I think, 12 years). Thus, you
absolutely truly know from the start what one of those hours will cost
engine-wise: The cost of the engine divided by 2400. That's it, period.
If it breaks before that, you'll get a new one prorated. So, if you fly
200 hours per year, your cost savings could be substantial. Also it
uses a lot less fuel. If you fly a lot, that will pay of sooner.


--
Thomas Borchert (EDDH)