Toroidal Opposed Piston Engine

thingiverse

A 4-cylinder 8-piston powerhouse engine. I've printed half of this marvel and it runs smoothly (the other half is essentially identical). If you want to print this, I've designed it to assemble easily with 12mm-long M2 screws and six bearings that boast an inside diameter of 8mm, an outside diameter of 22mm, and a width of 7mm - standard skateboard bearing dimensions. This design is inspired by toroidal-shaped pistons and cylinders, which form the basis for a full engine model based on opposed piston 2-stroke technology. If you only use half of it, however, you'll get a boxer engine design.