Seeing as the name of this website is The Old Motor, you can be sure that on occasion we will come up with some of the oldest, oddest and most unusual means of motive power to be found. Today we are sharing with you a form of engine that is new to these pages, the Hot Bulb Engine.
We can thank Stefan Marjoram for introducing us to the video above from Bottleneck John who cleverly substitutes one of the engines for a drum machine, while he plays a dobro and Lars Astrand accompanies him with a 1930s Supertone mandolin.
To learn how a hot bulb engine operates, refer to the drawings above where you can view three strokes of the four-cycle engine: In the first stroke kerosene or a heavier fuel is first injected into the hot bulb (heated before starting) along with air through the intake valve into the cylinder; Some of the fuel burns when it first enters the bulb, but for complete combustion it requires additional air that is added during the compression stroke; When the two mix in the hot bulb under pressure the ignition occurs and the power stroke follows, the forth and last stroke is the exhaust.
To learn more view the book Gas, Gasoline and Oil-Engines by Gardner Dexter Hiscox published in 1898; in it you can see illustrations of many types of early engines. You can also learn more about how a hot bulb engine works here. Below is another interesting video showing the starting procedure and the running of a one-cylinder Kromhout M1 hot bulb engine that was built in 1929. You can also view a series of videos showing some exceptional operating model hot tube engines here.