Nico71 - Lego Switchless Pneumatic engine mk2. With stacked 4 valves instead of side by side, one cylinder and two speeds gearbox. Expected to me mounted soon in a two wheels creation
World's first full-size Lego car can hit 20 mph, powered by insane, 256-cylinder compresed air engine | Extremetech
technic - Is a N2 or CO2 paintball tank a viable power source for a LEGO pneumatic Engine? - Bricks
Lego Pneumatic Engine: Possible Damage from Baking Soda and Vinegar? - Bricks