Large Model Association Forum

Hi, i have a Zenoah zg38 engine i am fitting into a plane but i have a problem with the muffler. on the 38 the muffler fits on the rear of the cylinder head which is fine but i want the pipe to come out of the side instead of downwards which all proprietry mufflers seem to do. the engine is inverted. is it difficult to make a muffler for a petrol engine and what metal-thicknes ect should i use.
Thanks John Whyte 3017

John,
There was an article in a recent Model World showing how to make a silencer for a petrol engine,

Barrie

Thanks for that Barrie, it is the Oct 2008 issue and i have ordered a copy from Traplet. Why does no one use the standard silencer with the ZG38 as that would fit inside the cowl.

Cheers John.

John

The simple answer is that at most flying sites the standard silencer is to noisy.

John

I have use the stock 38 muffler on 3-4 past models......the 'louvers' are hammered flat and silver soldered up......2 x 1/2" dia holes can then be drilled in the sides of the rear section of the muffler body and 1/2" st/st tubes silver soldered in. All of mine have had the pipes pointing down or to the rear, but I see no reason why pipes cannot come out of either side. My 1st attempt many years ago used a single pipe and I lost performance....fitting a 2nd restored performance.

True, it's not the quietest in the world, but with a decent prop (19 x 10 carbon) it's perfectly usable at your average club site

Phil

Thanks for your advice, there is'nt much room behind the engine to the bulkhead and the pits muffler i have (Brison) is too big. if i move the engine forward i would have to remove a lot of the cowl plus the engine would stick out too far. The stock muffler is small and the pipes out of the side would be near scale. Now i just need to find some stainless pipe.

John.

John, it dosen't have to be stainless pipe, in the past I have hand rolled thin steel sheet into a tube then silver soldered the seam, works just as well but takes a little mre time.

Barrie

I Always use ZG38s in my models. As the ex owner of Ratby Aeroplanes, and who have made in cowl exhausts for 25+ years I can help you in where to get the materials and also how to make them extremely quiet ( using the same idea as a Gun Silencer)
They will fit into the same area as the original exhaust does so no probs. As long as you can silver solder you can make one in about an hour. I will even send you a drawing if you wish. Call me on 01527 550753 if you feel I can help you.
Regards
Mike Ellis 652