wrote:

The lower fuel burn comes not from the higher energy of Jet-A, but
rather from the higher compression ratio which converts a higher
percentage of the energy to useful work. Diesel comes closer to an
ideal Carnot cycle than gasoline.


How much better fuel economy and efficiency would result
if modern internal combustion designs were made easily
available to the GA fleet (versus diesel engines) ?

These new diesel engines employ the latest of modern technology
in terms of materials and design, where our old Lycomings and
Continentals are basically 75 year old technology. Not a
fair (or even logical) comparison IMHO.