This engine is a two cylinder Stirling engine of my own design with the pistons and dispacers running in the same cylinder. This arrangement makes for interesting looking linkages. It would have been simpler and more efficient to have mounted the crankshaft above the cylinders,but I think it looks more impressive with lots of rods and levers.This is a very busy looking engine when it is running especialy when running slow. The pistons have a diameter of 19mm with a stroke of 12.6 mm, the stroke of the displacer is 19mm.