hi help ,which is the best tune pipe and manifold set up that never fails ?
at the moment ive got 2 gas boats one is a 26 cc zenoah this has manifold with a 2 part type clamp over cooling system which also holds on the manifold to the engine with 2 o rings,then tune pipe slides over manifold with o rings again and more cooling ! yep you got it fails on the o rings at the manifold and eventually leaks ,tune pipe to manifold also eventually fails n leaks after a longer period .
other boat is an old man o war made by bill wood of performance models in florida with a homelite engine ,this has a simple system of a manifold with water injected in to it then a silicone joint between the tune pipe and manifold this works fairly well but eventually the silicone fails , ive been told that the zenoah would not like water injected into the manifold !!!!!!!!1

so what do you guys reckon sorry for the long one on pipes its the only thing that lets me down now!

For the manifold coupler, you can check with CC Racing Engines...they now sell a no leak manifold, that even if the Orings fail, no water leaks into the header...works real well and is available for both 7/8inch and 1 inch headers. As for the slide on pipe with orings...these typically leak if your pipe bracket is exerting stress on the pipe...in other words, let the pipe fall into place and fit the bracket to it making sure the bracket isn't forcing the pipe to one side or the other...I have had some last for whole seasons with no problems doing it this way. Hope this helps.

For the silicone coupler pipes...replace the silicone coupler (typically used for nitro engines = lower exhaust temps) with a teflon coupler.

hi marc thanks for the reply ,just run my zenoah boat which is not quiet finished yet still ironing out the problems the last one being the exhaust system,well it ran great for 10 mins or so then wheeeeeeeeee loads of noise and you guessed it it had blown the o rings out of the mainifold cooler coupler thingy , not had to much trouble with the joint between manifold and tune pipe as you say make sure it lines up well etc but i am finding the o rings wear out after a while,any way back to the manifold coupler just spoke to a friend of mine who said just use a bolt on manifold straight to the engine with no cooling pipe , what do u reckon hes a model helicopter guy he reckons use a helicopter type exhaust for reliability !
ill try n put up a pic , excuse the mess as its still in the experimental stage