Sure, but it depends on the details.
For example my IO540-C4 is rated at 250HP. This is with 8.5:1 pistons. Variants of it do 350HP, I believe, with I think 10.5:1 pistons and a (only marginally) thicker crankshaft which is accomodated by fitting thinner bearing shells
The 350HP engine has a very poor reliability record however.
The 250HP version seems to be OK, though turbonormalised TIO540 versions rarely if ever make TBO without a top overhaul.
So it is a spectrum... where on that spectrum do you want to be? If you are flying a PA46...
achimha
I have never owned a DA40 or 42 diesel but my observations of the scene suggest that, yes, while we rarely see conrods sticking out of the side of the cowling (car engines really are built well in terms of pure structural strength margins, because weight of the moving parts is a non-issue) we do get almost everything else around it packing up.
Diamond have had ECU problems; not usually resulting in an in-flight engine stoppage but resulting in a landing followed by a fire engine - a regular sight at certain FTO locations. That kind of thing is sure going to put a damper on using the plane for a remotely serious trip. You would need balls of steel to do something like
this in a DA40TDi.
They have also had cooling system problems. Diamond claim these were mostly confined to the DA40; Thielert claim in turn that Diamond bodged the DA40 cooling system against Thielert's instructions, and since the bodges were not transferred to the DA42, it did not have those issues. I don't know...
And it goes on, all the way down to crap plating on engine fittings which force the replacement of a lot of bits at the Annual, due to corrosion. I know some people involved in Diamond maintenance.
I am sure aero diesels will be considered "proven" one day but it is too early for me
Don't get me wrong - with the avgas availability matrix in Europe, I would install a good diesel (or any other avtur burner)
tomorrow.