In case any of you guys don't go to mazspeed forums, I just got through building my own muffler for my 82. It has a single 2.5" inlet, and two 2 inch outlets. The exhaust enters the 2.5 inch tube, has an open chamber about three inches deep, then passes through the smaller tubes, which are perforated, and surrounded by medium coarseness SS wool, like a glasspack style. The full muffler is 16 gauge steel, with the chamber plate, and side panel section double thickness 16ga. It's very beefy, and should be able to stand up to the high rotary temps. As soon as I get the exhaust installed, I will try my best to post some sound clips. Of course if it sounds like a Civic
with a 6 inch coffee can tip, I may just go crawl under a rock for a while, lol.....

Including tool purchases and sheet metal bending, I'm at about $150. I also have enough SS wool left for another 2 mufflers possibly. Unfortunately I have to wait a week or possibly more before I get the exhaust done. The cash for the convertor and header is a little hard to come by right now. Probably going with a Bonez 2.5" convertor, an RB header, and a custom bent remainder. Hopefully this sounds at least as good as a Pacesetter or RB. Yeah, call me an idiot, but I like how Pacesetter mufflers sound.

Okay, you can laugh now,

 

That's certainly an interesting looking muffler LOL. As long as it performs well who cares what it look slike. I'll be looking forward to hearing sound clips. Maybe you can make a muffler, smaller in circumferance with larger inlet's and outlets, something a 12A Turbo can handle LOL

 

how big is that thing?

 

I'm sure I could, hehe. My whole reason for starting this, was the $300 barrier on the aftermarket stuff. I found it hard to understand that I could true dual my 98 Ford truck including mufflers for $325, but the same would only get me a muffler on an RX7, and a little change left in my pocket.

 

The body of it is about 16 inches long, 3 inches shorter than the stock muffler. Diameter is pretty close to stock size.

 

do you have any pics of the guts? or during construction?

 

Could have purchased some universal Borla mufflers, they sound great. Looks good by the way.

 

Damn! Is it as heavy as it looks?

 

Interesting idea, let us know what it sounds like and how it holds up over term.

 

It never ceases to amaze, that a bunch of people who own such lightweight cars are so obsessed with how much every part weighs, lol. It's like talking with a bunch of road bike guys, lol. Yeah, it's a little heavy but not nearly as heavy as it might look. GUESSTIMATING only, about 15-20 pounds. My experience has been been that light mufflers usually sound like hammered crap. I don't have a scale, hanging, bathroom, or otherwise. If I did I would weigh it.
It should hold up fine, unless my engine is a blowtorch and I don't know it. 16 gauge steel is pretty thick, and it's double thickness in most of the critical parts. The SS wool was more like thin wires bundled together, than wool.

Here are the only other pics I have. Mostly the outer can and one with the outlet tubes in it. Once the wool came in I got the rest done in one sitting, and I was a little too dirty to be handling the digital cam every few minutes.

 

It looks good. I am really curious as to what it sounds like. It is a good idea for those of us who can weld (not me) and don't have a whole lot of money for exhaust parts.

 

If I could make my own convertor, believe me I would, haha. I am also very anxious to hear it as well. I could hook it up to my Ramcharger for a preview, but it popped a freeze plug on the back of the engine. I couldn't run it more than a few seconds without worrying about overheating it.

 

One of our local guys (posts under the name 84stock) has just swapped a muffler from a Chevy Cavalier into his 1st gen, along with a custom exhaust line from the stock exhaust manifold back. It's even quieter now than a stock set-up. Total cost including the custom work was in the low $100's, and the muffler itself was scored from the wreckers for $10.

As retarded a design as the Cavalier is, from 1995 onward they came with a full stainless steel exhaust system and the promise from GM that "by the time it wears out we'll have elected two presidents." Time will tell if this swap was a good idea or not, but so far so good.

 

^^It'll be interesting to see if the interior holds up to the heat. It's probably more restrictive than a stock FB muffler. In my opinion, quiter sucks. I want a nice tone that is nicely audible. Not too quiet, but not too loud

 

^^ mine sets off car alarms

 

Two presidents?....big whoop,thats only 5-8 years depending on how deep into the 2nd term you wanna go!

The stock junk muffler and cat on my buddies 4cyl. Mustang, lasted for 14 years and over 220K miles! Dont need to be stainless to last.....'course,living in CA keeps everything under there in pretty good shape.

 

Mine too, but I think that a lot of our cars do that on this forum.

 

Mine doesn't :-( I thik that will change soon enough ;-)

 

Werd. My muffler is 21 years old, and it hasn't fallen apart yet.

Eventually, I will put my RB muffler on, though.

 

could be anywhere from 5-16 depending on how many terms each prez has...

 

That was exactly what my reply would have been. Thanks for saving me the bother.

GM claims it will last "two presidencies," but the jury is still out on the actual lifespan of these exhausts--- they may well last far longer than that. After all, warranties for typical exhaust components are usually much shorter than the expected lifespan.

The stock RX7 muffler is one unusually skookum unit, lasting two or three times as long as typical boinger mufflers installed on boinger vehicles do.

Stock boinger mufflers usually last between four and eight years depending on the make (Nissan is notorious for it's biodegradable exhaust systems. Toyotas seem to fare better) and also the environment in which the car lives. Obviously if you live in areas where there is snow and salt on the roads in winter your exhaust won't last as long as that of the same car operating in Arizona.

The reason for optimism with my friend's car with the Cavalier stainless muffler is that stainless is more heat and corrision resistant then steel. It therefore will not become soft and then deform due to the heat produced by the rotary.

The stock exhaust manifold and (low-restriction) exhaust system means that the weak link in the hp-loss-due-to-restriction factor could be the GM muffler---- except that this muffler was designed to handle the flow of an engine producing upwards of 150 hp, the DOHC 4-banger used in the Cavalier. (these cars also use the less-powerful iron duke 4-banger, but one would assume the exhaust system would be common to all Cavaliers and Sunfires from 1995 onward.)

My friend's car is quieter than stock (good if you don't want to attract the attention of cops but bad if you want everyone to stare and say "look at that cool guy in the cool car!"--- you hope. ) but pulls at least as well as a stock '84 RX7 for the year. If the muffler lasts only one year he'll have gotten his ten bucks worth. If it lasts several years we should all consider this option when it comes time to replace the stock muffler with an equivalent.

 

I respect anyone willing to tackle a project by building their own parts. Nice work. It's great to see someone else not jumping on the big name bandwagon.

 

It certainly takes an ability to think outside the box (not to mention the expertise and tools required) to circumvent the greedy Mazda parts departments and aftermarket exhaust system suppliers by designing and manufacturing your own components. If you have the tools and the know-how, why not?

Besides, unless this inexpensive Cavalier muffler proves to be a viable long-term option building your own may be the only way to avoid getting financially ***-raped by Mazda, Racing Beat and others.

 

well...I will say that i applaud your creativity and those welds are definately clean...but I don't really get the motivation aspect. I mean I put 2.5" exhaust on my 81 with a resonator, extended the primaries on the header and put a GREAT looking polished stainless magnaflow muffler for 350 bucks. Then again i live in florida where you can run no cat and there's plenty of boriquas willin to work on rx-7's, especially nice widebody 81's, for cheap. Then again my car does wake up the neighbor's and sounds like a bunch of pissed of bees in a can. Gotta love the *brap!* AMEN!!!

 

He already said what the motivation was and you confirmed it.