I bought this Stirling Hot Air engine from the Al Cropley collection. Unfortunately, on the way home, my friend wanted me to bring it into his house to see it run. I was reluctant, as I wanted to look it over first, but he was rather insistent, so we gave it a try. His theory was, "if a little heat is good, a whole lot of heat is better" ... I kept saying it shouldn't take this much heat, but he just got a bigger blow torch!!! Take a look at the next photo!