On May 13, 12:40*am, Stealth Pilot
wrote:

the engine problem seems to provide the most unsolvable dilema when
attempting to build a small aircraft.

I agree. It has been the main problem for the past 100
years..........

I'd hate to think that the
prospect of engine conversions was passing.

It's not passing, just evolving, but slowly. We just have to accept
the fact that other than for small engines (~30 hp or less) all mass
produced units will be water cooled, which complicates things for
aircraft use. I happen to be in the camp that thinks that, over all,
water cooling will prove to be an advantage. We as home builders
still have more to learn before my assertion can be proven.

In the mean time our options are somewhat limited. We either use
existing aircraft motors, convert air cooled auto engines (a
diminishing supply), or take Veedubers suggested path of converting
water cooled lowers to air cooled units.

Simple sand casting, increasing availability of CNC machining and off
the shelf parts may provide another path for the budget minded?
=========================
Leon McAtee