Classic Chamber Installation

[astglenn]

I will be performing a refit on my side pipes this weekend. I have opted for the classic Chambered, 3" I.D. Cobra Pack. I am going to be using the 28" version, which will be a bit quieter than the 24" "Stock" length.

So long as Fed Ex freight cooperates, I will get some pics of the fabrication work and what it takes to get the conversion done.

The Classic Chambers are a very reasonably priced conversion tube. My set, which are at the top of the price list, were just a tick over $200.00, delivered. The owner of Classic Chambered, Erick, seems to have a very good understanding of what he does for a living and is extremely helpful in selecting a tube design. He actually builds the tubes, these are not off shore, mass produced tubes.

[Pierre B]

A photo or two, or perhaps more written information, would help me understand exactly what this refit entails, and what it yields in return. Excuse me, please, for not being up to speed on this matter, but I am intrigued.

[Bob Cowan]

I did that last winter. The result are very good. The noise level is decrease, even on the track. And it's a softer more mellow sound. That harsh blat from the stock pipes is gone. The sound is awesome.

I didn't do a before and after dyno test, so don't know about power.

http://www.ffcars.com/forums/showthread.php?t=240604&highlight=exhaust

[rich grsc]

Keep us informed. I am really starting to hate the harsh sound from the stock FFr side pipes. Good photo's and part #'s used are greatly appreciated.

[astglenn]

I forgot Bob had chronicled this mod. I will do a brief show and tell as well. Rain today, so I should be able to get the mod done tomorrow. I will post the events when completed.

Onward proudly!

[Rootbeer Roadster]

I'm looking forward to your pictures and impression especially related to noise level.

[David]

Looking forward to checking it out Glenn! I should be finishing up my headers tomorrow!

David

[astglenn]

Well I got started on the retrofit yesterday. I ended up opening up not only the stock muffler, but the new Classic Cobra Pack as well. I wanted to forever end my question of what was in there. That included the new muffs too. That led to a couple of hours of muffler design research on the web. Well I have learned the following, so far.

I started with a 20" long x 2.5" I.D. Glass pack (Stock Kit Pipe) This is my car in stock form.

http://i124.photobucket.com/albums/p18/astglenn/sidepipe%20retro/photo5.jpg

Stock tube removal
http://i124.photobucket.com/albums/p18/astglenn/sidepipe%20retro/photo.jpg


Whats in here?
http://i124.photobucket.com/albums/p18/astglenn/sidepipe%20retro/photo2-1.jpg

[David Hodgkins]

I bet this is going to be good...

:)

[astglenn]

OK. The work is done. Let me say that I am very impressed with the Classic Chambered "Cobra Pack" retrofit mufflers. The car sounds awesome. Much deeper, quieter and the high frequency racket, that made my roadster sound like a Cambodian Trawler, is all gone. Reversion popping is reduced by a very large percentage as well. That is another attribute that my car exhibited that irritated me to no end. I am glad to have it gone. The mufflers that I utilized are Classic Chambered, 3" Cobra Packs, "Packed" They are available "packed" or "un-packed" for the truly adventurous.

I was skeptical when I opened my boxes. So skeptical in fact, that I cut one of the new Cobra Packs apart to look inside. I also spoke with Erick, the owner of Classic Chambered, at length, while spreading the guts of his muffler out on my bench. Initially, I was less than amused that I had another glass-pack style muffler on my hands. I had visions of a "chambered" muffler. Classic does make those, but these were not it. I ordered wrong. How different could it possibly sound? I mean, a glass pack is a glass pack right? I had glass pack guts spread out all over the bench and fiberglass strands in places they should never be, in order to further my understanding of what a glass pack is, what it does, and why. Erick is a very forthright guy and explained why his "Cobra Packs" would sound substantially different. I fully expected that this would prove untrue and continued with the install in a skeptical "this is going to suck" thought process. A chambered tube / resonator combo was already in my mind and Erick would be happy to build me two. He remained confident that I would love the 28" x 3" Cobra Packs"

To look at the muffler, it is a glass-pack, just like our stock tubes. The construction is very good. Other than the size of the hole down the middle and the longer body, it rather seems identical. The diameter of my new "Cobra Packs" at 3" is larger by 1/2", over the stock tubes @ 2.5" I.D. which really ends up to be 2.250" once past the approach throat of the perforated tube. The louvers in the "Cobra Packs" are a bit different, in they are located in a helical pattern that is a bit tighter than the stock tubes. The packing is substantially different between the two. One is a random roving mat and the other a unidirectional, stranded mat.I also selected a LONGER tube length. The stock tubes are 20". I went with a 28" inch tube length. My plan was to leave the collector alone and shorten the outlet elbow. I stood to reason that a 30% increase in tube length should work toward my goal of sound control. I was not disappointed. The other chief difference in my installation, was that I turned the direction of flow, to place the sound louvers (perforated tube) into the incoming exhaust flow. In theory, this should promote sound waves to telegraph through the louvers and into the packing. Again, I was not disappointed. This makes a big change in the pitch and volume of the exhaust note. I have become convinced that a pleasing, aggressive exhaust note is only partly a game of decibels. Frequency has as much or more to do with the overall presentation. The car now sounds very aggressive, in a controlled, frequency enhanced way.

My car is outfitted with Powerjection lll. One of the big benefits of the system is a very comprehensive laptop interface that shows me in real time, what the reference telemetry is doing while underway. I can tell you that the exhaust flow is enhanced with the 3" I.D. of this system. my engine is a 306, it stands to reason that additional benefits would be recognized on larger displacement engines, in a predictably linear manner. My fuel maps had to adapt with more fuel at peak torque points to normalize the AFR values. That is hard data that is beyond the mere suggestion of enhanced flow. The car also feels more responsive to the throttle. I could not be happier.

I attempted to perform the installation below, using common methods that should be within the capabilities of most advanced hobbyists, or a fairly routine, reasonable costs basis job for a local exhaust shop to perform. I have attempted to get rid of the difficult miter work, by the use of a reducing coupler at the merge collector to muffler intersection. If all headers were straight and plumb, it would not be an issue. In the real world, a little slack to gain some alignment allowance, without the need of compound miter cutting, may be handy to some folks. I also came up with a simple reinforcement of the mid tube hanger that is long standing problem for repetitive cracking. It is a low tech solution that is easy and effective. It wont win a design innovation award, but it should work well and be easily accomplished by most folks. David Borden will no doubt give me a good lumping over it. :)

I have not shown the guts of the Classic Chambered mufflers. I feel that they are Erick's property to display or keep a secret as he sees fit.

Onward.................

Here is what is in there. This is a stock Perforated Tube.
http://i124.photobucket.com/albums/p18/astglenn/sidepipe%20retro/iphonepics078.jpg

The choke point in the stock tube
http://i124.photobucket.com/albums/p18/astglenn/sidepipe%20retro/iphonepics079.jpg

Stock tube on top, Classic Chambered 3" on bottom. Lower right has been disassembled and welded back up. The diameter difference is striking.
http://i124.photobucket.com/albums/p18/astglenn/sidepipe%20retro/photo13.jpg

Inner Perforated tube / Stock Muffler
http://i124.photobucket.com/albums/p18/astglenn/sidepipe%20retro/photo11.jpg

Inner Perforated Tube / 3" "Cobra Pack"
http://i124.photobucket.com/albums/p18/astglenn/sidepipe%20retro/photo12.jpg

The "louvers" are typically installed with their back facing the exhaust flow on the stock tubes. At least that is what I found on my stock tubes. I installed the new "Cobra Packs" with the louvers facing the exhaust flow. My mission was to get as much sound wave into the matting as I could.

[astglenn]

I formed these reducing couplers in the shop. They are made from 3.5" Walker exhaust tubing, expanded to 4". They slip over the collector and muffler tube in a fairly tight fit. They get cut back to approximately 2" OAL. The 3" end will slip up the collector to expose the intersection, then be pulled down onto the 4" tube. At that point, much angular adjustment is possible without mitering the collector or muffler tube. The tube can be mocked up, tacked in place, removed and bench welded. Even a slight "S" can be tweaked into the coupling if needed to overcome an angular offset problem, without looking too obvious.
http://i124.photobucket.com/albums/p18/astglenn/sidepipe%20retro/photo19.jpg
http://i124.photobucket.com/albums/p18/astglenn/sidepipe%20retro/photo22.jpg

We are all aware of this pain in the tail, repetitive hanger crack. Here is a simple fix. It is really easy to do when performing a retrofit.
http://i124.photobucket.com/albums/p18/astglenn/sidepipe%20retro/photo14.jpg

Cut a 1.5" band from the old 4" tube.
http://i124.photobucket.com/albums/p18/astglenn/sidepipe%20retro/photo15.jpg

Cut it into a 180 degree section
http://i124.photobucket.com/albums/p18/astglenn/sidepipe%20retro/photo16.jpg

Slot it with some oversize to fit over the stock hanger bracket. Leave room to clear the tube to bracket weld bead.
http://i124.photobucket.com/albums/p18/astglenn/sidepipe%20retro/photo17.jpg

Make sure you get a 2200 lb drill press involved for drilling a few 1/4" holes through the band!
http://i124.photobucket.com/albums/p18/astglenn/sidepipe%20retro/iphonepics051.jpg

[astglenn]

The holes provide a place to plug weld the band in a few places. Alternatively, the band can be quickly welded to the muffler casing and hanger bracket. This should distribute the load much better and reinforce the connection enough to prevent future cracking.

http://i124.photobucket.com/albums/p18/astglenn/sidepipe%20retro/iphonepics055.jpg
http://i124.photobucket.com/albums/p18/astglenn/sidepipe%20retro/iphonepics068.jpg

[astglenn]

I shortened my tail elbow to 6" OAL before welding it up. I also rotated it downward to a 50 degree orientation. Now I can really blow dust all over my black car! I found that bouncing the sound waves, off the pavement, actually changed the sound a bit. Less high frequency tone is the result.
http://i124.photobucket.com/albums/p18/astglenn/sidepipe%20retro/iphonepics069.jpg

A completed retrofit, ready to go.
http://i124.photobucket.com/albums/p18/astglenn/sidepipe%20retro/iphonepics064.jpg

Heat shield on and back on the car. The outlet is about 1" closer to the rear fender. I think it needed to be. I really like the look of the 50 degree turn-down of the outlet.
http://i124.photobucket.com/albums/p18/astglenn/sidepipe%20retro/iphonepics075.jpg

[Fifty-Two]

Great write-up Glenn! Serious kudos on some nice fab work - simple always works best. And boy do I wish I had your TIG skills!

I assume that since they are glass-packs, there is a finite life to these pipes just as there is with the FFR's? Or is the different type of glass mat in the "Cobra Packs" supposed to have a longer life?

And thanks for giving the raw data (fuel maps, etc) behind your findings as well. It makes sense that with the larger ID, flow should go up ... but its always good to see some numbers that demonstrate it was truly the case.

- John

[astglenn]

Classic Chambered claims that the mat is a lifetime deal. The owner worked for Dynomax for quite some time. I tend to believe that he is a very straight shooter.

Thank you for the kind comments. I could have raced the fabrication up. I really wanted to do something that the average guy can do, without a fabrication shop in his pocket.

[Fifty-Two]

Classic Chambered claims that the mat is a lifetime deal. The owner worked for Dynomax for quite some time. I tend to believe that he is a very straight shooter.

Wow ...
Something I'll definitely be looking into now. Much appreciated Glenn!

- John

[Jeff Kleiner]

Thanks Glenn! Timely info; I blew over the 100dB limit at an event this weekend and have to quiet it down to keep running at the venue.

Jeff

[astglenn]

I will get my hands on a dB meter today Jeff. Let's find out where these things are at. I will get a sound bite posted up as well. The real positive on this conversion is that it is fairly inexpensive and really quick to do. $250.00 all up and a long day.

[Someday I Suppose]

Glenn very nice write up, and great looking car. Black cars are the best <G>

-Scott

[Rootbeer Roadster]

Is the packing made from fiberglass?

[astglenn]

Is the packing made from fiberglass?

To me, it looked like a blend of fibers. It is a much different material, with a specific orientation to the lay of the stranding. I think I am pretty sure what it is, but I wont hazard the guess. I would say that it is at least partly (S) fiberglass, which is much more dense than the typical (E) type glass strand found in typical sound mat.

[astglenn]

Glenn very nice write up, and great looking car. Black cars are the best <G>

-Scott

Thank you. Oh the perils of a black car. Indeed great when clean, clay-rubbed,micro-polished, glazed, sealed, stroked with only high quality microfiber, dry-detailed, burnished, inspected under 4 types of lighting and prayed over.

Next time, it's going to be flat white, put on with a Home Depot roller! Jeff Kliner had it picked when he used to say "Not a Waxer" I get it now. Man do I get it.

[vnmsss]

Very nice work Glenn!!!! Thanks for the detailed description.....We sure coulda used a set of these for the Coupe last year! The 25 Hours race has a strict 95 dB limit, and I guarantee you that's a hard number to hit in the still of the night.....;.)


Next time, it's going to be flat white, put on with a Home Depot roller! Jeff Kliner had it picked when he used to say "Not a Waxer" I get it now. Man do I get it.
Sounds like a red and white car I know......Refrigerator white (Home Depot) and AutoZone red, with custom clear coat courtesy of Manny, Moe and Jack! K

[Cameron Autosports]

Great write up Glenn. Not only very talented in the shop but a good composer of words. I know this article will be a real benefit to a lot of owners. Thanks for taking the time.

[Someday I Suppose]

Glenn I am going to be right there with you, the microswirls that appeared in the car over the winter while sitting in a bubble sort of amaze me :-)

But yep when polished wow does it look mean.


Thank you. Oh the perils of a black car. Indeed great when clean, clay-rubbed,micro-polished, glazed, sealed, stroked with only high quality microfiber, dry-detailed, burnished, inspected under 4 types of lighting and prayed over.

Next time, it's going to be flat white, put on with a Home Depot roller! Jeff Kliner had it picked when he used to say "Not a Waxer" I get it now. Man do I get it.

[astglenn]

Glenn I am going to be right there with you, the microswirls that appeared in the car over the winter while sitting in a bubble sort of amaze me :-)

But yep when polished wow does it look mean.

I stopped using my bubble. The mars that were inevitable when rolling the vinyl over the car were making me crazy.

I found the BEST and I mean BEST products for detailing and keeping up with the paint on the car. My car is a real pain because the clear is on the soft side. Nice. 9K for paint and it comes back with soft clear. $#$@$%^

Check out PoorBoys products. Specifically a material called Black Hole. Amazing stuff. I was a 3M / professional Products user for a long long time. Poorboys entire line of micropolishes and the wonder called Black Hole, are amazing.

[Someday I Suppose]

Glenn, thanks didnt mean to hi-jack this thread. I have picked up a thing of Black Hole but haven't tried it yet. Do you use it as a last step product, or put a wax on after black hole?

I am sure your right with regards to the cover causing some of the marring. I have it off now, but been wondering if there is a way to support the cover so that its off the car when not inflated. Have to give that some more thought. :-)

[astglenn]

Glenn, thanks didnt mean to hi-jack this thread. I have picked up a thing of Black Hole but haven't tried it yet. Do you use it as a last step product, or put a wax on after black hole?

I am sure your right with regards to the cover causing some of the marring. I have it off now, but been wondering if there is a way to support the cover so that its off the car when not inflated. Have to give that some more thought. :-)

I use the Poor-Boys #2,3, or 4, "depending on how things are looking" micro polish, then finish out with the Black Hole. The black hole is the best swirl remover I have ever seen. I used to use corn starch, then it was on to the 3M stuff. The PB Black Hole is head and shoulders better!The final final is the Red, hard wax. That will keep it pretty good for awhile. I use Maguires, "Final Finish" or the Poor-Boys spray Detailer as a spritz with a high quality microfiber towel. This will keep me from wanting to commit suicide for the most part when the car is in a presentable phase. Most of the time the car gets a once over with the duster wand. My kids jump horses on the next parcel over, so the dust is always around. This black paint nearly drove me to counseling. I guess it worked out for the best, now I'll drive it with bugs, mud, stuff that comes out of the south end of a north bound bird, whatever, all over it. Lisa calls it progress. Pffffft.

I am going to fabricate a simple bow frame, from EMT tubing, to make a cage for the bubble to go over. It will come down from the ceiling on a simple bridle / lift winch, like the cone of silence, in the old Get Smart series. It is the only way to make it happen that I can come up with. It would be super handy if Tupperware would make a BIG casserole burper.

[astglenn]

Very nice work Glenn!!!! Thanks for the detailed description.....We sure coulda used a set of these for the Coupe last year! The 25 Hours race has a strict 95 dB limit, and I guarantee you that's a hard number to hit in the still of the night.....;.)


Sounds like a red and white car I know......Refrigerator white (Home Depot) and AutoZone red, with custom clear coat courtesy of Manny, Moe and Jack! K

I tell ya. I think I like your painter better than I like mine, already! I will have a dB meter tomorrow. I am a total devise, tool and equipment hussy. :) had to have it. This IS R&D! I will get some values posted up so we can all know what it is now.

[Jeff Kleiner]

Jeff Kleiner had it picked when he used to say "Not a Waxer" I get it now. Man do I get it.

Hey Glenn, I still say that (have "mydream" Thierry tell you about when he caught me "detailing" the roadster at LCS with a bottle of Simple Green and one of the hotel's towels).

Just FYI, the course dB meter is set up perpendicular to the track and 50 feet back at a point where a driver would ordinarially be hard on the throttle. With our pipes pointing straight out the sides they directly blast it. A buzzy 4 cylinder exhausting out the back might actually sound louder to our ears but the meter will often say otherwise. Turning our outlets down can reduce the level the meter sees.

Jeff

[David]

Outstanding work Glenn, looks great! Cant wait to hear them...

David

[astglenn]

Outstanding work Glenn, looks great! Cant wait to hear them...

David

Thank you David. The car is in the shop. I am actually going to build my own dash finally. Let's get together mang!

[Powerstick]

Am I late or what? Yes, the packing material is a fiberglass blanket. No reports of the Cobrapacks getting louder since I started building them in 2006.

astglenn - awesome writeup - thank you.