Good point on the conrod material. I expect the shafts, crankwebs, crankpins and piston bosses on these little ones may not be particuarly sturdy. The rod is the best "weak point".
Here is the 0.006cc (0.00037 cu. in.) Valentine "nano bee". It's conrod must be the diameter of a sewing needle [X(]
http://www.ebay.com/itm/Rare-Valenti...item5aef938fbc
Has anyone ever seen one run?