RE: EXAUST PIPE INSIDE THE FUSELAGE
The latest version of the whole Pressure cowl. The front part of the cowl is double skinned. The inner skin is the tight fitting shroud around the engine at the front end of the cowl. The incoming air is ducted over the head fins and through the case fins. You will notice the vertical air inlet on the front of the cowl but not on the inner shroud. The inner shroud forces the air to the sides of the case. fuel going up the front transfer passage cools the front of the engine. The idea of this system is not just to cool things down but to maintain an even engine heat throughout the engine run.
The shroud in this cowl is a fibreglass molding. You expressed a concern about the heat inside the cowl. Mike is correct, excess heat is being carried away by the airflow. My first shrouds were made from the cardboard tubes from toilet rolls. The never burned out. They were also a perfect fit over a Nelson racing engine. Somebody new what they were doing when they designed them, (The toilet rolls that is)
Ed S