Onetrack, I've done expert reports as a consultant for the stock market float of "new engines". The reality is that current aircraft engine technology is well understood, light and easy to maintain.
Overhead cams, variable valve timing, etc. etc are heavy and produce no worthwhile result for an aircraft engine. Advanced manufacturing techniques such as plastic flow head bolts, etc. are of no use to engines that must be rebuilt. The current automotive manufacturing technology is NOT designed for rebuilds, overhauls, etc., it is designed on the basis that the engine is going to be thrown away.
Without starting the whole Lean of peak thing again, the BSFC of the old Lycoming engines is just fine, of course there is stuff like direct injection, etc, but the technology is not only complex but Heavy and unmaintainable in the field.
There is a world of difference in design philosophy between an automotive engine that spends most of its life at 20% of rated output and an aircraft engine running at least 55% of power at a fixed rpm.