This is an engine I just completed. It took me about 4 weeks to build, and it runs extremely well. Although I show it running on compressed air here, it would run just as happily on low pressure steam. It takes about 10-15 psi of air to run it. It has a 1" bore, and contrary to what I said in the video, has a 1 3/4" stroke. the crank arms are arranged at 90 degrees, giving this engine the capability to self start. I sell a 25 sheet set of plans for this engine for $25 Canadian funds, and can be reached at [email protected]