I mean, there's being cheap and then there's getting a new aviation engine FAA certified. Those aren't exactly the same thing and Bob the dentist who likes to take his Cessna 172 up on weekends can't simply approve a new engine.
This is why buying a new spec Cessna 172 from the factory floor today will still come with the good old Lycoming O-360 engine, introduced in 1955.
Cessna sells ~250 172s per year, nowhere near enough to justify new engine approval.
I'm no expert, but I'll express a wish: that modern supply constraints mean Lycoming O-360 engines may be noncompetitive to an engine design conceived today. Perhaps these old engines are suppressing the investment into an invention that turns a 250 person market into a 25,000 one?
This is why buying a new spec Cessna 172 from the factory floor today will still come with the good old Lycoming O-360 engine, introduced in 1955.
Cessna sells ~250 172s per year, nowhere near enough to justify new engine approval.