Tell me.....what is the trick, hot setup for getting speed out of these gassers? I noticed the props are mostly sized by 10" & 12" pitch ranges through various diameters.

Alcohol/Glow conversion is the first step, second is to reduce the prop dia. and increase the pitch. finally get a very clean airframe.

Good luck
Bobby

Methanol and Nitro with a glow plug..We get 180 MPH on 100 inch formula race planes using Zenoah twins and turning about 10,500 rpm...Props are somewhere around 18 x 20, carbon fiber....Or use a 289cc twin, 23x27 carbon prop, 9000+ rpm, 230+ MPH..
Speed is expensive, how fast do you want to go ???