[Ol' Ron]

A word of caution here. The 239 ci 100 hp engine actually only produces about 80 hP. John Lawson wrote a book called "Flathead facts" This is an engineering white paper on the mdifications done to this engine and the testing of every modification. Aircraft engines produce approximately .5 hp per cubic inch our Cessna 182 had a 470 ci engine rated at 230 hp. very few flatheads will make that kind of power, so the weight factor is not the only problem. I do think a 150 p Flathead can be built with a reasonable amount of reliability under 450 lbs. I have a 294 coming into the shop in a few days and I'll weight it.