Hello All, I am drawing up a design for a water-cooled exhaust manifold for a small engine. It would be a simple design of an exhaust exit pipe mounted to a flange, with a tubular copper heat exchanger liquid filled coil wrapped around the exit pipe right near the cylinder. The copper would have to be soldered or brazed. Normal plumbing solder melts at around 400 degrees F. I know exhaust gases can exceed this, therefore I would worry about the joint melting and the exhaust assembly falling apart. My question is, if I were to braze this copper together with a silver compound with a higher melting temp, would it hold? What exhaust temperatures would I expect straight out of the cylinder of a 35cc 4-stroke engine? I would like to use copper or brass for the heat conductive qualities and corrosion resistance, and to be able to braze/solder the coiled heat exchanger to the exhaust pipe. Any thoughts? should I use aluminum?