10.5 commando engines run just fine on BP 93 octane. I've even used 91 octane gasohol (10% alcohol) without a problem. If you build an engine with 11-11.5:1 then you need race gas or additives. Toolmanmike
I was using 110 octane race fuel, but at $8.00 a gallon, I had to try the pump gas.
I now run 93 octane and some lucas octane boost.
It only gives you three octane points no matter if you use 6 ounces of octane boost or a gallon, the chemical composition stays the same.
I did not even have to dumb down the timing and it runs just fine.
I do run some leaded 110 every now and then to keep things lubricated.