No accounting for taste here.  These excellent turbo 2.3 litre flat air-cooled sixes have 150 hp, and 210 lb ft. and work well in VW dune buggies, and possibly for light airplanes?

This second generation Corvair, beginning is 1964 was a pretty good car, and pretty, too. Had a rear-mounted, flat, air-cooled six, with a 180 hp turbo version available.