There is an engine in the U.S. patent offices (so nobody can use it)
developed by 'Smokey' who wrote a self help column in Popular
Science magazine for years, that doesn't use a radiator. It takes the
heat from the engine and uses it to preheat the fuel to pre detonation
temperature and thus allows 55% of fuel energy to be used rather
than the 12% now used in conventional engines.
You should look into this. I became aware of it a few months ago.
It can be found in the 1980 or 1984 issues.


Jay wrote:

I'd like to see some discussion on surface radiators instead of how to
build plenums directing air through auto radiators. Seems like you
could braze aluminum tubing onto the inner surface of the lower cowl,
add a sheet of insulation on top of that on the inside and you'd have
a particularly low drag radiator. The cowling is going to get blasted
with turbulant air anyway, might as well heat that air up a little as
it swirls by the surface.

The holes in the front of the cowling make some sense for an air
cooled engine where the temperature differential is high and you can
direct some air (with lots of drag) directly onto the heads. But if
you have a water cooled engine, you can do things differently and it
would seem with lower drag. Drag is the primary predictor of top
speed, beyond horsepower even.