1.
http://www.gizmag.com/pictures/galle...rid-engine.jpg
2.
http://thekneeslider.com/images/ellwoodhybrid.jpg
3.
http://gardeningisfun.files.wordpres...ing-engine.jpg
4.
http://i.ytimg.com/vi/NZ2CiIq64Lc/default.jpg
So far the best engines I found doh these engins are concept and in small size but they are real working engines....you can check the same on youtube.com Great engines and Great Brain
also check sterling engines in youtube.com
soon I will be working on SpitFire Engine For project purpose....