Methanol is a popular fuel for small engines used in radio-controlled models, but comes at a higher price than gasoline. It’s also harder to source and can be a mite corrosive, too. Gasoline comes with some benefits, but running it in a methanol engine usually requires some mods. [David] and [Bert] worked together to build a mixture controller for just this purpose.

The controller uses a solenoid to control the flow of gasoline to a conventional methanol-tuned carburetor for a small RC engine, allowing it to be accurately tuned to run gasoline well across the whole RPM range. Having gone through many revisions, all documented in a big forum thread, the latest version uses a Seeduino Xiao controller and a BMP280 pressure and temperature sensor for determining the right fuel/air mixture for the conditions. A small OLED screen can optionally be fitted to help with configuration of the mixture controller.

The system has worked well in testing, with [David] and [Bert] reporting that they have “converted engines as small as 0.3 CID up to large radials with this system.” It’s a promising tool that could be handy to have in the RC modeller’s arsenal.

These tiny engines have other applications too; they can make for one crazy power drill, that’s for sure!