"Richard Isakson" wrote in message
om...
"Marc J. Zeitlin" wrote ...
Hyperbole isn't necessary here - no small internal combustion engine has
ever gotten near .25, and the Bourke engine certainly doesn't, but it IS
theoretically possible. Using ceramic materials instead of metals may
someday get us there.

Ceramic engines have been built but the material is far too brittle to
make
a useful product.

Rich

Hey! Some of the new engineering ceramics are ductile enough to pull into a
wire. Mark isn't talking crockery here. Ceramics are already used in
engines. Diesel exhaust valves in one instance, turbocharger hot sections
for another. If you make the piston crown, combustion chamber roof and
valves out of highly insulating ceramics, diesels can get a LOT lower SFC.
They're working on it.

Bill Daniels