Hi Paul,

 I hope the  Oshkosh experience was very good.  The TTC project is
 very impressive.

 I’m gradually working through my radiator and oil cooler issues, and
 also building an exhaust header / tangential muffler.  I have a
 couple of questions on the latter.

 Please see the attached, although very crude, drawing.

 I am using the Racing Beat SS header, with short 2.5”x 1.75” OD .065
 304 SS tubes welded in place.  These will slip into 0.65” 1.88” tubes
 that will in turn be welded into a 6” 304 SS .065 cylinder/muffler.
 On the front, a 90 degree 1.88” tube is used to reduce the length of
 the 6” tube and significant weight.

 Due to space and other constraints, I need to bring the 3” tailpipe
 (also .065” 304 SS) out of the *rear* of the muffler and up.  This
 gives me at least 3 options: 1. A straight 3” pipe welded to the rear
 of the muffler. 2. Squeeze the 3” tailpipe into a fish mouth (your
 previous drawings showed an area about 1/2 of that of the tailpipe).
 Or weld up a larger fish mouth. 3. Or, allow a short section of the
 3” tailpipe to remain inside of the muffler, which could be closed
 off and drilled with (e.g. 0.5”) holes to arrive at the same exit
 area as the fish mouth design.  I am wondering if this might be a
 more conventional muffler design and possibly allow better sound
 reduction?

 The prior concerns regarding the longevity of any metal living
 “inside” the muffler have been noted. However, with a Renesis engine
 having exhaust ports coming through the iron housings, as well as a
 cooling tube, both giving lower exhaust temps, do you think this is a
 concern for .065" 304?

 Thanks for your input,

 Scott Gettings

 You are on the leading edge Scott. Nothing like this has been built
 yet. The RX8 side port exhaust is  a little cooler so it should work
 all right. If it burns through opposite the exhaust ports you can
 weld on doubler patches.


 Paul Lamar


Scott,  Suggest that you investigate 321 S/s as 304 is a very low grade Stainless.  Remember the exhaust temp will get up to 1800 degrees which is rather warm.  Your design is similar to what I made and is still alive, but I have not the cooling tube.  Neil  Unger

Nice work Neil.

Paul Lamar


Typically 309 & 310 are used for high heat applications, 309 is good for 2000F and 310 2100F.
Be sure to use the correct filler rod the material you are working with or you will be wasting your time using these more expensive grades.
I would not call 304 a low grade steel, they all have their place in the appropriate application.
Andrew Campbell.




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