During the 8th flight of my RV8 with 13B Turbo, I experienced an exhaust leak at the turbo exhaust flange. I mistakenly used brass exhaust nuts  which are twice as tall as regular nuts. They work great on most engines. I should have know better, as the temperature at the turbo outlet, under the insulation is much higher.

The brass nuts softened and deformed into a flange face at the washer! Once the tension was gone, the heat & vibration did the rest.

The exhaust gasket blew where the gap was widest, at the top.

The escaping heat burned thru the insulating jacket and the stick on reflective aluminum. Then the fiberglass cowl charred, I smelled that!

I was close to my destination, and high, so I was able to pull off the power, put down the nosed and get on the ground without incident.

I'm disassembling it now, looks like I need 4 high temperature lock nuts and a TO-4 exhaust flange gasket. I should review and improve the insulation over the turbine housing. Also I need to repair the charred area of the cowl, which might be in the form of an aluminum access hatch.