A thing I thought about some years ago, but it would be easier to do with an S&S V twin bottom end. The Lycoming O-360 is an air cooled flat 4 with a 5 1/4 inch bore. 2 of those barrels stuffed into an S&S bottom end with a 4 inch stroke would make just over 173 inches. That's about 2.83 liters for the inchic impared. Bet that would be hard to kickstart!
