RE: Quique Somenzini YAK-54S 73"
Since I don't have my 73" yet (and don't have the 72" either) I can't be sure of just what weight we are talking...
It has been hard in the past to gas power panes these size due to airframe weight/engine power ratio. But something like the 3W28 might do nicely...
They 3D 10-11 lb ExtraFun's with it...
In the same weight class is the ZDZ 40RE coming soon... 2.4 lbs... looks like maybe 2.75 lbs with ignition. Lighter than the 3W28i... You can go tuned pipe or inv. pitts and only be maybe 3/4 lb more than an O.S. 1.60 bird. Then taking into account takeoff weight with 18 oz of glow fuel instead of 12 gas... you aren't far off at all...
And a 40cc would haul a 12 lb plane all over the place and have serious power...
At 5.35" from firewall to prop hub, you'd only need 1/8" spacers behind the engine and a hole cut out of the firewall for the carb to stick through.
There would be hardly any cutout required in the cowl thanks to the rear exhaust...
Hey, I'm talking myself into something here...