Rotax 912 (UL?) HP, Air cooled, direct drive, simple construction, cheap, reliable, electronic ignition and injection: Sounds like you want a 2180cc or 2400cc VW derivative with SDS EFI and ignition. About 75-80 HP, about 160 lbs, Cost: about $8000 (engine about $5500--with starter and alternator, no carb or magneto + EFI + fuel pump, injectors, etc--maybe $2500?) That ain't free, but $100 per HP is dang reasonable for a ready-to-run engine with a strong prop hub (zero failures) and the trimming/tuning capabilities that the SDS electromagic adds to the package. "Something old, something new . . ." The flat-4 VW can't earn those extra credit points.