After many months of searching for a suitable engine (Lycoming O-360-A1A) I decided on the more available Lycoming O-540-E4B5. I made my decision very carefully taking all the pros and cons into consideration. I live at fairly high altitude ( 5500ft) and the local airport has only some 770 Meters of usable runway.
My decision was also motivated on Nat Puffer's experimentation with the Franklin 220Hp six cylinder engine. I made careful weight and balance calculations and came up with a modification that will keep the CG in exactly the same place as the plans built version.
I have increased the size of bulkhead F"0" which in turn extends the most forward tip of the fuselage to F"-13". This leaves more than enough room to place the 25Lbs battery ahead of F"0". I will in no way exceed the all up gross weight of the aircraft (2050Lbs) so this will mean that I will have to carry less fuel when flying four up.
I will be installing a 3 blade composite fixed pitch propeller which I intend building myself. I have had Nigel Field run some numbers on Prop Opt and it looks like I will be shooting for a 68" diameter X 98" pitch. This combination should give me the best compromise between cruise and climb. It is estimated that my Cozy-MKIV 540 will climb at 2600'/min at 5500' density altitude .... we'll see!
This is what my engine will look like when installed
This is an installation on a Berkut.
This info is not recommended for others to use and I will not be held responsible for any occurrences. I am installing a Lycoming O-540 engine at my own risk and will not hold Nat Puffer or Cozy Aircraft liable for any damage as a result of my own experimentation.
This is what an IO-540 looks like on a Berkut.