Cut away of a Dyno Max muffler #18381

[rumblefish360]

Ok ok ok, I’m bored....so I got to thinking....
Yea yea yea, I know that’s dangerous....
So. What makes that stock replacement muffler so, almost stock quite?

I don’t know. But I do now!

These were inexpensive stock replacement style mufflers from dyno max (IIRC) purchased as an experiment on sound control on my ‘79 Magnum w/360/4. Hooker super comp headers are on the engine. There tube size is 1-3/4. The exhaust pipe is 2-1/2. The mufflers inlet & outlet are 2-1/2.

But the inside! The inside says .... as small as 1.7 or 1-45/64. That is where the center outlets pipe slides into the middle muffler pipe, which is 2 inch inside diameter. Hell of a neck down from 2-1/2. That diameter stays inside the muffler for ten inches where it then necks down.

The 4 holes around the center tube are hard to measure and I’m not taking part further. They appear to be about an inch or slightly larger. These holes are the only way to get to the second chamber and to exit the muffler. Yes, there are actually only two tubes in the muffler.

The tabs are not welded. Which was a surprise. Though I haven’t ever had trouble with them leaking or coming loose on any dyno max muffler.

You want a quite muffler? This is it! Super quite. So much so as I could here the gears of the trans mesh. Every rock and pebble.

Other models in the line have smaller inlet/outlet sizes. 2-1/4, 2 inch. I’m sure there insides are the same as this one. The depth of the chamber in the first picture below is close to 9-1/2 while the outlet side (second picture) is 4-1/2 inches deep. Bigger the chamber, the better at sound cancelation. As well as a small tube diameter. The case over all is 24 inches long, 10 X 4 width/height.
These are sizeable mufflers in there length. Probably not very easy to fit on an A body. b & C bodies.... probably OK. They were a bit tight on my ‘79 B.

I hope you enjoyed the fruits of my boring day for a few minutes of entertainment.... If anybody wants to donate a muffler...LMAO.

 

[dukeboy440]

yep another case of getting what you pay for

 

[Cuda416]

This is kind of interesting because for a summer job in college I worked for a company at which all I did was put semi mufflers on a flow bench and test them, then I'd cut them open to provide detailed drawings. All of them, as I recall, simply pressed the tubes in the inner chamber walls but the walls were spot welded to the outer shell. It was one of the more interesting "temp" jobs I ever had.

-C

 

[MoparMike1974]

I used to love flowmasters because of the heavy duty gauge steel they are made of. Then one day I cut one open and found the baffles are paper thin. Once the baffles rust out the whole thing is junk.

 

[1Fast340]

Yep isnt it great to take things appart and learn a few things in the procces
Have seen plenty of that over the years from the cheaper lines of stock replacement mufflers,have cut alot of mufflers open to take a look over the years.I much prefered to cut windows into them after first tapping some on them to find the walls if there where no visible signs of them from the outside.
i believe the 18331 is a Walker Sound FX muffler wish is a very cheap line.
The QuietFlow SS mufflers tended to be a much better line much closer to OE,the whole thing tend to be much more solid,just holding them in your hand you will feel the difference and less restricition,but that might have changed since then

 

[rumblefish360]

yep another case of getting what you pay for

I don’t how you mean what you said but I’d agree with you if you agree with me on I paid for a quite muffler and got one.

This is kind of interesting because for a summer job in college I worked for a company at which all I did was put semi mufflers on a flow bench and test them, then I'd cut them open to provide detailed drawings. All of them, as I recall, simply pressed the tubes in the inner chamber walls but the walls were spot welded to the outer shell. It was one of the more interesting "temp" jobs I ever had.

-C

Oh wow! That’s weird! I’d love to put some on a flow bench. No one really provides the mufflers flow rate. Just dyno max on there performance mufflers and Heartthrob. I don’t know how to convert 222cfm @10hg to 28hg.

Yep isnt it great to take things appart and learn a few things in the procces

Yea it is. I was just wondering. Tom Hand sent me some DIY stuff to make my own mufflers. I’m going to give it a shot for fun while trying to make a serious effort in making a well constructed quote free flowing unit. I’ll try and couple it with David Vizards ideas.

 

[Mattax]

Oh wow! That’s weird! I’d love to put some on a flow bench. No one really provides the mufflers flow rate. Just dyno max on there performance mufflers and Heartthrob. I don’t know how to convert 222cfm @10hg to 28hg.

Vizard did years ago and has published it in a few places, including Performance with Economy.
I had an Accurate muffler run on a bench to compare it with the SuperTurbo I was taking off.

 

[dukeboy440]

I don’t how you mean what you said but I’d agree with you if you agree with me on I paid for a quite muffler and got one.



Oh wow! That’s weird! I’d love to put some on a flow bench. No one really provides the mufflers flow rate. Just dyno max on there performance mufflers and Heartthrob. I don’t know how to convert 222cfm @10hg to 28hg.



Yea it is. I was just wondering. Tom Hand sent me some DIY stuff to make my own mufflers. I’m going to give it a shot for fun while trying to make a serious effort in making a well constructed quote free flowing unit. I’ll try and couple it with David Vizards ideas.

I misread what you typed. Ignore my previous comment. My bad

 

[dartfreak75]

Every 318 iv owned (quite a few) has been straight piped none of them have been over bearing loud. They have all been single pipe with manifolds. Is there any performance benefits in a straight pipe ( no muffler at all) or does it hurt performance? Iv heard that no muffler hurts performance and can damage valves etc is any of that true?

 

[d55dave]

When I was young and poor, my 80 volare ex cop car, 318 with single exhaust needed a muffler. I straight piped it but left the cat converter in. It sounded great and was not too noisy.

 

[dartfreak75]

When I was young and poor, my 80 volare ex cop car, 318 with single exhaust needed a muffler. I straight piped it but left the cat converter in. It sounded great and was not too noisy.

That is how I have always driven my 318s. Idk if its cause 318s are low compression or what but they are not that loud. My buddy straight piped his new Silverado (04) and it was unbearably loud.

 

[Mattax]

Every 318 iv owned (quite a few) has been straight piped none of them have been over bearing loud. They have all been single pipe with manifolds. Is there any performance benefits in a straight pipe ( no muffler at all) or does it hurt performance? Iv heard that no muffler hurts performance and can damage valves etc is any of that true?

As long as there is enough piping to keep atmospheric pressure away from the exhaust ports. That's what would be bad. 14.7 psia is atmospheric pressure. a=absolute That makes for lousy exhaust extraction.
If you want to think about it from a combustion point of view; look at it from the two parts of the exhaust cycle. the first part being the pressure from combustion being released and the second from the pumping of the piston.

 

[Mattax]

Some great photos and discusion in this thread.
Restrictive Mufflers

 

[rumblefish360]

Some great photos and discusion in this thread.
Restrictive Mufflers

Oooo. Thanks, I think I forgot about that one.

I misread what you typed. Ignore my previous comment. My bad

No no! It’s all good. I just didn’t know where you were going with it. Sarcasm? LMAO....

Every 318 iv owned (quite a few) has been straight piped none of them have been over bearing loud. They have all been single pipe with manifolds. Is there any performance benefits in a straight pipe ( no muffler at all) or does it hurt performance? Iv heard that no muffler hurts performance and can damage valves etc is any of that true?

There is truth to it.... it is like the old adage, race parts (Top fuel zoomy headers) on a stock engine (318) does not mean the car goes fast.

 

[1Fast340]

Every 318 iv owned (quite a few) has been straight piped none of them have been over bearing loud. They have all been single pipe with manifolds. Is there any performance benefits in a straight pipe ( no muffler at all) or does it hurt performance? Iv heard that no muffler hurts performance and can damage valves etc is any of that true?

Dont worry about it,its not going to hurt a thing and wont cost you any power.
Not a fan of that straight pipe sound but thats up to anyone what kind of sound we all like,on lower performance engines i like a muffler/glasspack that just takes the edge of the sound slightly.

 

[Mattax]

As long as there is enough piping to keep atmospheric pressure away from the exhaust ports. That's what would be bad. 14.7 psia is atmospheric pressure. a=absolute That makes for lousy exhaust extraction.
If you want to think about it from a combustion point of view; look at it from the two parts of the exhaust cycle. the first part being the pressure from combustion being released and the second from the pumping of the piston.

Calvin Elston's insight about exhaust flow's effect on combustion is good reading IMO.
At Speedtalk, screen name exhausted; "What is [exhaust] Blowdown Length?" p.2
Basic rule of thumb from his Exhausting blog: What tube size off the head?

 

[AJ/FormS]

Every 318 iv owned (quite a few) has been straight piped none of them have been over bearing loud. They have all been single pipe with manifolds. Is there any performance benefits in a straight pipe ( no muffler at all) or does it hurt performance? Iv heard that no muffler hurts performance and can damage valves etc is any of that true?

When I called up TTI to order their stuff, I asked for the dual 3" full length system. I was promptly told that, that would be too much for my little 367, and I wouldn't have enough back-pressure.
So stop the clock right there.
So now I'm thinking to myself. Back-pressure. What could possibly be good about back pressure? What is the first thing anybody does when they hop up their engine? Headers right? Headers work by EXTRACTING the exhaust, by initiating a pull on the carb to get the air moving a wee bit earlier. That's what they do. So back-pressure would destroy the header's ability to do that. We all know that processing air is what the engine does, and the more it can process, the more potential to make power it has. How can back pressure help in any way.
So Still thinking, I see a picture in my mind of a race car at the track, running straight headers, no exhaust at all. If backpressure was a good thing, wouldn't racers have some kind of restrictors welded on their header exits?
So still thinking, I see my lowly lawnmower,3.5 Briggs that has been running with a blown "muffler" for 10 years, and seems to be doing just fine. And I see my roto-tiller dumping straight to atmosphere, and it roto-tills just fine. And then I see the Karts,at the track where I am a tech-inspector and a volunteer flagman, and the Karts all have short sections of straight pipe on them;every one. And my mind goes into a million different rabbit holes, and none of them support back-pressure.
Restart the clock.
Ok says I, I'll just take the full-length dual 3s then. And I'll do whatever it takes at my end to ensure the engine lives.
Ok Sir, how would you like that shipped?
So I bolt my dual 3s on and the engine ran perfect, and has done so since 1999. Yeah it might be a lil loud at full song,but I sit ahead of the exits, and it takes a while before the sound catches up to me. I often slow down,just to hear those screaming banshees,lol. I didn't buy the 3s to make power; I bought them to suck heat outta the exhaust,so the gases could have a place to cool off and condense,to provide a low-pressure area for the headers to dump into, and 3" exits so the engine wouldn't have to work so hard to pump the gasses out the ends. 3" pipes have a lotta metal and a lotta mass, and they suck a lotta heat outta the exhaust.
The thinking seems to be right, at least to me,cuz dang that car is fast..... for what it is; just a lil 367. The 70 pounds of exhaust doesn't seem to slow it down one bit.

 

[rumblefish360]

For best performance, you certainly want ZERO back pressure. To larger or an exhaust pipe can hurt. Just like my above example on race parts on a stock engine. While it is on the extreme side of an example, it is still true.

What you (the new guys to this) needs to know is how much power your engine is making and how much a simple exhaust tube will flow . Or how much power can be made through an open pipe at 2-1/4, 2-1/2, 3... etc... Then how much the muffler will flow. According to David Vizard, the flow rate of a muffler should be 2.2 cfm per HP.

Street bound guys looking for a reasonably quite ride can error on the size smaller while drag racers go larger for the max HP. A place street guys visit once in a while and drag racers see every time.

The hardest part of D Vizards exhaust calculation method is having the engine on the dyno and finding the exact length of straight pipe off the collector/reducer without a muffler that makes best power. There is your pressure termination box.

Then comes the task of making one, and then connecting the exhaust via H or X pipe of the proper size into the rest of the exhaust. Followed by the mufflers of the appropriate size for the power on hand.

The muffler I cut up with above would be just fine for a ever so slightly modified engine with the traditional dual exhaust that is a low powered engine. Considering the internal pipe size restriction, these mufflers would be good at I’d guess the basic stock low compression mill that could barley wheeze out 275hp.

These would be fine for the guy that just wants the dual tail pipes on his ride. And maybe a 2-4 bbl. upgrade. Nothing else. Being there the “Sound XF” line of mufflers, the ever so quite rumble can be heard at the tail pipe. And I really mean “ever so slight rumble.”

 

[67Dart273]

I STILL remember about 1976 or so when I put the 340 in the old Landcruiser. I used GOOD OEM equivalent replacement REAL ACTUAL Corvair turbo mufflers from Walker or Marement. These cost MONEY and they were HEAVY

Friend of mine heard about it and priced them. "Too much." He came into the store with his proud new mufflers............Thrush "turbo muffs." I went back and got one out of stock, a Maremont. Brought it up front and back then I could take that cheap *** light weight Thrush and HOLD IT OUT on my outstretched hand and forearm, something I could not BEGIN to do with the heavy built Maremont.

Told him, "come back in about a year" when that Thrush is rusted. That is just about how long they lasted, too!!!

Sad news is today I don't have any idea where you could buy a REAL Corvair turbo muffler built like the OEM

 

[1Fast340]

I STILL remember about 1976 or so when I put the 340 in the old Landcruiser. I used GOOD OEM equivalent replacement REAL ACTUAL Corvair turbo mufflers from Walker or Marement. These cost MONEY and they were HEAVY

Friend of mine heard about it and priced them. "Too much." He came into the store with his proud new mufflers............Thrush "turbo muffs." I went back and got one out of stock, a Maremont. Brought it up front and back then I could take that cheap *** light weight Thrush and HOLD IT OUT on my outstretched hand and forearm, something I could not BEGIN to do with the heavy built Maremont.

Told him, "come back in about a year" when that Thrush is rusted. That is just about how long they lasted, too!!!

Sad news is today I don't have any idea where you could buy a REAL Corvair turbo muffler built like the OEM

Dont know about Corvair mufflers since i cant find them listed but Walkers Quietflow SS series was much better built than most other replacement style mufflers on the market just 6 or so year ago when i stoped working with exhausts.

 

[Unconventional]

I always liked Turbo mufflers. I heard a late model Challenger the other day with a custom exhaust of unknown origin, pretty sad, sounded like a pissed off Honda Accord.

 

[Unconventional]

Simple, compact, gasses make a couple of reasonably unrestricted U-Turns, and out.

 

[rumblefish360]

That’s not a turbo muffler!


This is a turbo muffler!
It’s dyno max’s Little metal U turn helpers that make these worth the price and the rest junk.
That’s my story and I’m sticking to it.

 

[1Fast340]

That’s not a turbo muffler!


This is a turbo muffler!
It’s dyno max’s Little metal U turn helpers that make these worth the price and the rest junk.
That’s my story and I’m sticking to it.


View attachment 1715241472

Those are good Turbomufflers,the Dynomax superturbo!

 

[dibbons]

The Corvair Turbo muffler had one pipe in the center/middle which I used as the exit/outlet end (but it might have been labeled as the inlet). I ran those back in the 1970's (dumped in front of the differential). I don't have a clue what they looked like inside. They were noisy, but my solid lifter, fenderwell headed, double-pumper 273 motor was actually louder than the exhaust note.

1965 Corvair Spyder Turbo Mufflers