... an engine that runs on Jet A and is lighter and smaller than the current
TSIO-550 and TIO-540 offerings that had only 270 HP continuous available to
~FL300?  Before anyone says this is no substitute for a "350" HP Lyc or Con
job (pun intended), realize that 75% of 350 HP is 263 HP.  And the maximum
altitude that a TSIO-550N can deliver 263 HP is well below FL300.

Theilert is now marketing a line of aero diesels set up for Jet A.  These are
actually auto engines that have been modified and have real live type
certificates and production certification.  They claim the lower power
versions they are marketing (~125 HP) are quite competitive in performance
with a "higher" performance 160 HP Lycoming due to the fact that their
turbocharged, continuous HP performance does not fall off as quickly with
altitude or temperature and that a "160 HP" Lyc doesn't seem to have as much
takeoff thrust as their "125 HP" engine.

(I am using quotes here because if the numbers and performance of both
companies are to be believed, someone is lying.  My money would be on
Lycoming, and probably Continental, fudging this by inflating their "takeoff"
power numbers by leaning for best power instead of running rich as the
manuals say to do.  What Theilert is doing is also open to discussion.)

The question I am raising is if someone were to market an engine that
actually produced an honest 270 HP up to higher altitudes, would it be
accepted?  More importantly and personally, would you buy it?

Let's put some (hypothetical) qualifiers on this.  Let's say it would have to
be lighter and cheaper than a TSIO-550N, and would have to have a better
PROVEN TBO in actual use in an aircraft;  i.e., kick the tires, light the
fire, ram it to the firewall from takeoff to letdown, and show me 2000+ hours
with no more maintenance than an oil change.

Never mind IF it can be done.  The question here is:  IF someone does it,
would YOU but it?

... just a question