Maybe there is some airfield next to you where you can buy some leaded fuel?
But i think it will be similar to 100 octane, in past it was used for tuning, but now there is also normal 102 octane fuel available...
F**k leaded fuel.
Acetone is good one aswell it actually has an octane rating of about 110. Might be better for price vs alko. Not sure on fuel system effects, but its a natural cleaner so I dont think it would cause any issues?
Heres a good read.
https://www.sciencedirect.com/science/article/pii/S2215098615302469" Experimental results showed that the AC3 (3 vol.% acetone + 97 vol.% gasoline) blended fuel has an advantage over the neat gasoline in exhaust gases temperature, in-cylinder pressure, brake power, torque and volumetric efficiency by about 0.8%, 2.3%, 1.3%, 0.45% and 0.9%, respectively.
As the acetone content increases in the blends, as the engine performance improved where the best performance obtained in this study at the blended fuel of AC10. In particular, exhaust gases temperature, in-cylinder pressure, brake power, torque and volumetric efficiency increase by about 5%, 10.5%, 5.2%, 2.1% and 3.2%, respectively, compared to neat gasoline. In addition, the use of acetone with gasoline fuel reduces exhaust emissions averagely by about 43% for carbon monoxide, 32% for carbon dioxide and 33% for the unburnt hydrocarbons.
The enhanced engine performance and pollutant emissions are attributed to the higher oxygen content, slight leaning effect, lower knock tendency and high flame speeds of acetone, compared to the neat gasoline. "