John wrote:
I recently ran into another case where someone sealed exhaust gaskets
with red high temperature RTV silicon sealant. I don't know off hand
what the temperature rating is for RTV but it has to be way lower than
what the exhaust flange sees. I will say the flanges and gaskets (the
thick spirotalic no blo style) were not leaking. Am I right in
thinking the lack of leakage is due more to the gaskets working as
required than the RTV?

John Dupre'

There's a car racer racing a Mazda rotary that uses rtv with no gasket
at all on the exhaust manifold. (Rotary exhaust temps make Lyc exhaust
temps look rather cool.) He says that the actual temp of the manifold
itself at the block is actually the same as the engine block. Makes
sense, if you think about it. Of course, the Mazda is water cooled &
won't be as hot as the cyl head on an air cooled Lyc. Is red rtv rated
to ~450 degrees?

Charlie