Exhaust Ports Enlarged, Turbo Did It

[Turbo Sporty 48]

Removed the heads which have 35k miles, 20k with a turbo.
Exhaust manifold was not always installed perfectly, gaskets blew out, whatever, did not fit perfectly, hot exhaust gasses ate some metal.
Time for new valves, springs, guides and seals anyway.
Thinking welding,
Comments, advise please.

[5mel42]

A long time ago, when the company I worked for still operated piston helicopters, we used to have the same problem. The engines were turbo-charged Lycoming TVO 435's and the headers had individual flanges. Sealing took place with the gasket between the flange and the corresponding face on the head. Various exhaust gaskets were used, but the ones that worked the best were referred to as No-Blows. They were a heavy steel outer with a crushable layered steel and asbestos inner ring. Even so, they had to be carefully installed and checked frequently because if they began to leak, the hot gases would erode the aluminum face on the cylinder head and you'd have an exhaust leak until that cylinder was replaced. When sent for repair, they came back with the face restored, so it appears that they were welded and re-faced. The exhaust gaskets on the Harley heads don't appear to be designed for a whole lot of back pressure since they just distort and fill up the space between the pipe and the exhaust port.There is a company in California that modified Shovel and Pan Head Harleys to a 3 bolt flange (Flo Headworks) setup. I wonder if they could adapt their flange to the Sporty head that could take the increased exhaust pressure.

[Turbo Sporty 48]

Found some Honda gaskets that worked pretty well.
They are almost like a big o-ring, tough stuff.
Pretty sure I'll find someone to do the repair, still looking, thanks for the info.

[bustert]

throw this slinky out and see if it returns
a big issue is the ring of fire, especially so if most of the fuel is not consumed in the cyl.
i will throw this out as an example. on the iron jug, there is an elevation that protrudes into the head and acts as a fire ring to help protect the very thin copper gasket.
this issue is more common than you think, the industrial white superior engine will burn out the head gaskets also so a fire ring is needed.
some times, the fire ring is part of the gasket, a tube with gasket in cased on the circumference which allows the fire to pass through and yet protect the gasket from burn out.
IF there is room, a stainless tube can be installed into the exh port that will extend into the header past the sealing flange, the gasket will be protected and basically seal against back flow.