Join Date: Jan 2012
Location: British Columbia
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I've used an air cooled engine with a dry exhaust for many years. One diesel Mechaninic was quoted as saying "If everyone went dry exhaust and keel cooling ,us mechanics would all be out of work." Wet exhausts are a major source of engine problems. I met a couple in Tonga who went thru 2 engines since 1996 due to corrosion on valves form wet exhausts. They now have a dry exhaust.
I use sch 40 stainless pipe ,wraped in fibreglass house insulation then aluminium foil, then three inch wide muffler tape, coated with silicone caulking. After days motoring in the tropics ,it feels cool to the touch.
I have experimented with high heat silicone hose. At the head of my air cooled engine, at 3/4 throttler it didn't burn, at full throttle it did. Friends with a water cooled manifold tell me it lasts them 2 years at the manifold, at the transom it has lasted them 15 years with no problem.
I have a piece clamped on my dry exhaust 2 ft from the head, for a couple of years and it shows no sign of burning , so it appears the trick is to get it some distance form the head.
One could use the flat wound stainless flex , then silicone silicone hose over it , the stainless to take the direct heat and the silicone to stop any escaping gasses.
The more solidly mounted the engine, the less flexing your exhaust takes.
Last edited by Brent Swain; 01-17-2012 at 05:19 PM.