Subject: Swiss Muffler
From: Rotary Engine
Date: 6/29/2007, 2:33 PM
To: AARotary Engine



>> After searching through many salvage yards looking for a radiator that >> would fit under the engine in the RV-9A, I finally found one. It is in >> my 2005 Dodge Hemi PU! By turning it 90 degrees and moving the exhaust >> pipe a little it fits just fine, at least in the 3D. JPGs are attached >> showing the arrangement. The muffler shown will not be used. Instead I >> plan on a QUIET muffler under the fuse. >> >> The rad core dimensions are 24" X 14" X 1.75" and the red boxes at the >> end are the tanks, each 1.5 W X 3" H. We plan to weld custom tanks on >> with the hose barbs on the firewall end. This produces a core volume of >> 588 cu. in. >> >> A couple of questions. >> >> 1. What do I do about the different lengths of the rad and the oil >> cooler to avoid a discontinuity, if anything? >> >> 2. How and where do I join the two exhaust pipes for max. efficiency? >> >> I heard that the Swiss builders invented their own muffler. Is this a >> good muffler and if so, are the plans available? >> >> I really hope I can avoid paying over $400 for a racing rad. >> >> Doc Custer >> Retired Software Engineer and sometime Audiologist >> >> Nice 3D's Doc. >> No solution for the first question :) All aluminum racing rads are $200 >> in >> the Summit catalog. I bought a Howe. If yours has plastic tanks beware. >> Have somebody weld up aluminum tanks. Bad place to save money. >> >> Join the pipes at 32 inches. Careful on the muffler. >> Most don't hold up. Tracy found one that seems to hold up. >> Last picture. I think it is a Flow Master from Warshawsky or some such. >> Anyway top and bottom are pressed steel and welded together around >> the sides. >> -- >> Paul Lamar ...No rotor no motor. > > If needed we will weld on AL tanks. > > Has anybody tested the plastic tanks to, say, 100 psi? If not, we will. If > doing this yourself, be careful: fill the rad with water as full as you > can > get it and then carefully add air pressure. Air can result in explosive > decompression if the rad fails. Water only squirts. > > In any event we need to move the inlet and outlets and fill/rad cap > location, so will probably have to weld on AL tanks to get the desired > locations. I would like to know how strong a salvaged rad is, regardless. > Especially the core as the tanks can easily be replaced. > > One more word of caution: each rad probably has a different strength. Test > before installing. > > I think I will do a 3D of the diffuser, rad and oil cooler. That will ease > the making of a male mold. > > Doc Custer > Retired Software Engineer and sometime Audiologist > > My experience is plastic tanks gets old, brittle and crack. Recent > information > suggest there is something in the antifreeze that makes them
brittle. > As far as I know we have never had a rad split due to pressure so far. Of > course > the pressure is limited to 30 psi. I cannot say that about oil > coolers however as rotary engine oil coolers are subjected to up to 150 > psi. > > Consider a two pass rad to get the inlet and the outlet on the > same end. Eases the plumbing. > > Paul Lamar ...No rotor no motor.
Although you can't see the inlet and outlet, the radiator is a cross flow. This means that both hoses could be on the after portion of the tanks with some loss of efficiency, I suppose.
I checked Summit Racing. Their search engine couldn't find a two pass rad. Or counter flow or any thing I could think of to call it. They do have some nice rads for under $200 though.
Doc Custer Retired Software Engineer and sometime Audiologist
Two pass rads are interesting. The flow length is twice as long but the flow area is half as much. In one regard they are less
efficient and in another more efficient. In theory for a given over all flow the velocity in the tubes is higher which is a positive thing. On the other hand the all important temperature difference is lower on average I think. Also since the resistance of the rad is higher the flow rate may be lower with a given pump. To quote Kays and London:
"In the design of liquid-to-liquid heat exchangers, accurate
knowledge of the friction characteristics of the heat transfer surface is relatively unimportant because of the low power requirement for pumping high-density fluids."
Paul Lamar ...No rotor no motor.
Tony Bingelis's book, "Firewall Forward" has a section on "Swiss" mufflers. The muffler consists of a tube rolled out of SS mesh surrounded by glass mesh (SS mesh would be better for our application, glass would not last) inside of a section metal tubing about 3-4 inches in diameter. The longer the muffler, the quieter I guess it would be. I don't think anyone has tried this on a rotary engine.
Brian Trubee
Yes they have and it burned out shortly as I recall :)
Paul Lamar

I think it's funny that the swiss re-invent the "glasspack" muffler
and everybody thinks it different than the hot rodders were using
in the late 50's!

Bill  Jepson


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