RE: Trying to get more speed with my warbird
If you plan to rev this motor for speed (high rpms), consider running the OS F (4c) plug. It has thick element and lasts longer than OS 8 or 3.
Regarding props, the best one for speed set up with 91 size motor is apc 11x9.
Regarding fuel, just run standard 10% nitro with all synthetic oil, but add 1 oz of Turbine oil per gallon, and your motor will run cooler and lasts longer from those high revs. Dont' bother with adding castor oil when running at high rpms. You can get a quart of turbine oil from your local private airport for a few bucks.