[It's more interesting if you advance past the 2:00 minute mark] This is my second attempt at a simple soda can engine. It will run slowly on one or two tea candles, but on an alcohol flame, as I show in this video, it really flies and I've clocked it at 860 rpm!
The displacer is actually a moving regenerator, a single piece of steel wool trimmed and shaped to fit the soda can and held in place with perforated bottoms from other soda cans. The diaphragm is made of bicycle inner tube rubber, the bottom of a soda can, a bottle cap, and a 1.5" PVC cap trimmed down a bit. It's attached to the cylinder can with a 1/2" PVC elbow.
The crank is of 1/8" stainless steel rod, the flywheel is the lid from a paint can, counterweights are magnets from old hard drives. The smokestack is made from a rolled-up soda can. I used some aluminum foil tape to hold things together.
I found it a bit difficult to get the thing balanced and it's still not quite right, but at least it doesn't jump around too terribly even at high rpm's. A lot of fun to build and even more to run!
