RE: Rossi 1.05 DF tractor engine with propeller..?
Flyer,
So what rpm's are you getting now on that engine and pipe? If you're still only getting 16000 rpm you need to work on your props... and from the photo's, I think your pipe is set rather short for 16000 rpm.
Also, if your plane reaches about the same speed on a 12x8 and a 10x10, maybe you should try an 11" diameter prop... perhaps an 11x8 or an 11x9...