This is where I got that figure:I had made up my mind not to add to this thread, but this is wrong.
Common forged pistons start to deform @ about 1450*. A heavily nitrous ed sbf I was asked to look at logged EGT's of 1680*. It melted the piston, uninstalled the replaceable exhaust valve seat and destroyed the top 6" of the header tubing.
edit- a ox-acetylene torch melts good steel @ 3000*.
I'm thinking they aren't talking about the temp of interior metal surfaces but the actual temperature of combustion.