I have already written about LiquidPiston and its XTS-210, but Avadi's idea is even more striking: it is a reciprocating engine that works as a rotary. Imagine an ICE with a single piston.

The prototype Avadi is a 250 cc engine that produces 30 Nm of torque at 3,500 rpm and 15 horsepower at 3,700 rpm. That sounds meagre, and compared to current water-cooled 250 cc engines with ...