Spiral displacer Stirling engine, pressure test. Extended run with "lost motion" dwell mechanism.

After making the video I found there was quite a bad pressure leak around the displacer rod.
The piston is also not a great fit and required quite a bit of oil to fill the gap.
Still, the pressure generated seemed quite high. Too high really.
To get the engine to run I had to reduce the displacer motion to a minimum.
Also the power piston displacement is not high enough. the piston and power cylinder are too small to utilize the potential expansion of the working fluid so there is a lot of "blow by" air escaping.

[@RoofAndAMeal4UsAll]

I love this stuff Good luck with your project! Spiral displacer is an interesting approach, lots of room for exploration there I would think.

[@peoplesresearchcenter6184]

Thanks for the good wishes. Seeing that the design/concept seems to work, I think next I will try making a high temperature version out of more heat tolerant materials. Initially I had put the first prototype on a hot wood stove and it ran great at a high RPM but the plastic and foam parts couldn't take the high heat and started melting down after just a few seconds, but it ran great as long as it lasted. This one was built from the left over parts of the engine that melted down on the wood stove. Not nearly as impressive only running on hot water, but still works.