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T-3 engine tin

That is why I use silicone to fill in the voids on my tins to reduce escaping air.
The fan housing is sealed with Hylomar. The heater tubes are filled with spray foam and sealed with Permalac. I intend to fabricate aluminum shrouds so they act as a radiator to absorb heat and would dissipate it faster. Otherwise I would make them out of stainless steel as it is a pour conductor.
I also like the caulking because it keeps junk like oil and hardware from getting trapped inbetween the cylinders.