MM01 - The OPITEC engine

Technical details
Year of construction 1998
Power piston stroke 10 mm
  diameter 12 mm
Displacer piston stroke 11 mm
  diameter 12 mm
Flywheel  diameter 55 mm
  material steel
Idle speed 1600 rpm
Energy source alcohol
Mass  860g


The engine was built from a kit sold by Opitec. I made several modifications:
The displacer cylinder was originally designed to be made of a stainless steel tube with a brazed-on copper cap; I used a segment cut off from an N2O whipping cream cartridge instead and a test tube as displacer piston. For lower friction and a tighter seal, I replaced the original displacer piston rod by a shaft liberated from an electric motor running in sintered bronze bushings cemented into the heatsink with two-component adhesive. Opitec included this same type of friction bearing into their later version of the kit. Aiming to minimize frictional resistance, I supported the crankshaft with two ball bearings from an old hard dive instead of brass bushings. All these changes were fundamental for making the engine finally run -- it now runs so well that I have to think about balancing the flywheels...
Further information on the new kit can be found on R. Fackiner's homepage: