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.