"Rogers, Bob J." wrote:

I was corresponding with Tracy Crook yesterday regarding my purchase of his
Reduction Drive and Ignition Controller and he volunteered that if he could
do it over again, he would use the non-turbo rotor housings in his current
13B engine set-up, because the exhaust splitters in the non-turbo housings
seem to help considerably in reducing the exhaust noise and force.   Like
Tracy, I am planning to use a 2nd Generation Turbo 13B short block, with the
89-91 Non-turbo Rotors ( 9.7/1 compression ratio) and no turbocharger for
installation in my Mustang II.

I have read a lot of discussion about the problems that several people have
had getting any exhaust system to hold up for very long and be quiet enough
when using the unrestricted exhaust ports in the 2nd or 3rd Generation turbo
rotor housings, if no turbocharger is used.  I understand that the lack of
an exhaust splitter in the turbo rotor housings should provide less exhaust
back-pressure and a corresponding increase in power, but how much?  And is
the increase in power worth the problems in trying to find a satisfactory
muffler system?

I t occurred to me that the higher power output available with the turbo
rotor housings might not be worth it if you go deaf from the noise of the
exhaust that they generate and if they constantly burn out all reasonably
light muffler systems.  Maybe the 2nd generation non-turbo housings still
allow enough exhaust flow-through to provide all the power needed for a
180-200 hp engine, while still offering a suitably quiet exhaust that does
not destroy a muffler in a few hours.  Since I am at the point of having to
purchase rotor housings for my 13B engine, I wanted to see if anyone else
had any opinions on which way to go.

I know that the exhaust pulse of the rotary engine has to be dealt with
somewhere in the system to make it quieter, and in doing so, a certain
amount of back-pressure is generated.  That can be done either with a bulky,
heavy, and expensive muffler system (which so far seems to have had limited
success with the unrestricted turbo rotor housings) or it can be done with
the exhaust splitter built into the 2nd generation non-turbo rotor housings
and a simpler, lighter, more compact, and cheaper exhaust system that may
last longer than your next oil change.

I welcome input or clarification from anyone who has reached an opinion on
this matter, including Tracy.

I don't think the jury is in yet on this subject. Something as simple
as going from .035 wall stainless currently used to 0.049 wall stainless 
might do the trick. For a two inch diameter tube 36 inches long the 
weights are 2.4 pounds for .035 wall 3.3 pounds for .049 wall.
This does not include the weight savings by drilling the holes.

What has not been tried, not to mention a lot of other things, is 
progressively larger holes towards the end of the tubes. No end cap 
should be necessary as the pressure wave should be fully dissipated 
by the end of the tube. The destruction of the end caps so far is to
be expected as most of them have been merely squished shut and welded
.035 thick material. Since these are small .065 thick material could be used
here without adding much weight and are unlikely to fail.

I would not spend $800 just to get new non turbo rotor housings for 
this reason alone just yet.

Paul Lamar
 
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