The following is a summary of a discussion I recently had relative to Swain Technology's exhaust system application.  I have focused on this system as it can be applied to the inside of the exhaust manifold as well as the outside.  To my knowledge, this is the only material that will not crack and flake off over time when applied to the inside of the exhaust manifold. -Stephen Heinrichs, #1046

Discussion with Dan of Swain Technology, Inc.
http://www.swaintech.com
Subject: Exhaust manifold heat management using Swain’s White Lightning ceramic coating.

I advised him of the coach and engine setup that I am working with and that my goals are to reduce both engine compartment heat and exhaust manifold casting maximum temperature.  Given that I have had a problem maintaining exhaust manifold gasket sealing, I am attempting to keep the manifold from reaching as high of a temperature as it has been.  A lower maximum temperature means less expansion and contraction which should help retain gasket integrity. Due to the fuel injection system I have added, the modified cam and somewhat of a lead foot, going up hills I am able to work the engine a little harder than would be true with a standard cam and carburetor.  All of this combines to add to the heating/expansion issues.

Based on my discussion with Dan, the current plan is to remove and clean the manifolds by having them hot dipped to remove oils and any residual carbon on the inside and then sandblasting or otherwise removing any significant exterior rust.  They will then spray the molten ceramic material (as opposed to baked on systems) on the inside and outside of the manifold.  Since they use a molten ceramic material, it instantly permanently bonds to the manifold.  On the inside, coverage will not be complete as application is basically “line of sight” with some flowing around corners and “bounce effect”.  With the center exhausting section being relatively short, he expects that they will be able to cover about 85-90% of the interior.  This will greatly decrease the heat absorbsion by the manifold.  The outside will then also be coated.  This will greatly reduce heat radiation inside the engine compartment and will also prevent the manifold from having hot and cool spots due to air flow and casting material thickness differentials.  This will make it more resistant to thermal checking or cracking.

When the manifolds are reinstalled, standard gaskets will not be used.  Dan has seen many of their high performance engine builders go to using orange RTV silicone gasket material.  A liberal amount is put on the manifold and then when the manifold is tightened to the engine the excess squeezes out leaving an extremely thin layer only in the minute pockets between the head casting and exhaust manifold casting.  This is the same procedure that Harry Day used on coach #400 that has served him well for 50,000 miles.  Harry used a silicone that also had a high copper content that became an extremely thin, molded in place exhaust manifold gasket.  Truing of the mating surfaces should also be done prior to having the ceramic coating applyed.