Air swirl in the combustion chamber to promote combustion isn't exactly a new idea. Main problem is keeping the fuel mist in the air instead of spun out onto the piston and head, where it won't burn.

There are all sorts of tricks out there, and since lawn mower engines are probably the last extremely low compression, sloppily engineered engines out there, almost anything will improve them (the typical suburban 1/4 acre lot push more produces more pollution in unburned hydrocabons and CO per week than the cars the family uses, this is why they were banned in S. Cal. a few years back).

However, a flathead engine is just about useless for anything but smoke and excess fuel consumption -- no way to get the air in and out. European engine designers dropped them in the 30's.

Peter

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1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!