Hello Jeff:

Great opinion of yours!  I was looking into the melting/decomposing
point of carbon fiber, and it may be as high as 2500C.  This is far
higher than the inside of an engine.  This maybe too optimistic.
Kevlar, which is similar to carbon fiber, decomposes at 400C.  But
this is still higher than the 200C or so temperatures which develop
inside an engine (that's the upper limit on my temperature dial).

If carbon fiber can withstand temperatures as high as 2500C and if it
can be made cheaply, than an engine not requiring a cooling system is
possible.  A hotter engine is a more efficient engine.

Where am I pulling the number "2500C" from?  Below!

Lower-quality fiber can be manufactured using pitch or rayon as the
precursor instead of PAN. The carbon can become further enhanced, as
high modulus, or high strength carbon, by heat treatment processes.
Carbon heated in the range of 1500-2000°C (carburizing) exhibits the
highest tensile strength (820,000 Psi or 5,650 N/mm²), while carbon
fiber heated from 2500-3000°C (graphitizing) exhibits a higher modulus
of elasticity (77,000,000 Psi or 531 kN/mm²).