Hello! Log in or Register   |  Help  |  Donate  |  Buy Shirts  See all banner ads | Advertise on TheSamba.com  
TheSamba.com
 
Ernst 411-412 muffler cross section and dissection
Forum Index -> 411/412 Share: Facebook Twitter
Reply to topic
Print View
Quick sort: Show newest posts on top | Show oldest posts on top View previous topic :: View next topic  
Author Message
raygreenwood
Samba Member


Joined: November 24, 2008
Posts: 14847
Location: Des moines Iowa
raygreenwood is offline 

PostPosted: Mon May 02, 2016 10:42 am    Post subject: Ernst 411-412 muffler cross section and dissection Reply with quote

So... I have been meaning to do this for years. Eventually I am going to be designing and building a new muffler for the engine I will be building for my 412 in the summer or fall….but this is not really about my muffler design…it’s about what’s inside of the Ernst factory muffler.

There is not much room for a muffler on these cars....and not much out there that is actually better than stock except the Bursch header...which will take work to fit, not available in stainless and not cheap. Or...the VW Heritage stainless T-bird knock-off which is very tempting. Or the vintage speed muffler which...is also interesting....which may also have some fit issues on the 411/412 at the rear breast plate that goes under the intake boot.

Yes there are plenty of HEADER systems that should work well....but fit is far from stock (Tangerine, Annendorp, CSP python).

What I would be really happy with…. is a muffler that works a good bit better than stock (mainly be being less restrictive and less overheating on the heads) but fits in the same space. A pretty difficult task actually.

So....years ago I noticed that among the usual suspects....stock VW branded mufflers, Wagner/Starla, Leistritz, Dansk and Ernst......that the best quality muffler and also slightly larger and heavier...the Ernst...made a noticeable performance improvement.

Not huge tire smoking improvement....but it noticeably ran cooler head temps and a good deal better throttle response that actually warranted a little tweaking to the MPS.

So...when I blew my engine years ago....it damaged the Ernst muffler and I have been threatening to cut it open to see what all is different from the other mufflers. It was also years ago that I had checked the volume on these mufflers with water and found the Ernst to be about 12-15% larger in volume ...which is part of it.

I lost that data somewhere. But I still have the Ernst and an NOS Starla/Wagner and an NOS Dansk...so I will be re-doing the volume checks on all……but for now…the Ernst.

So today...I finally re-checked the volume of (just a hair above 10.5 liters).....and cut open....the Ernst muffler! Very Happy

What I found:

1. These mufflers are a marvel of design in a tight space. A LOT of sound tuning design went into these units. They are not headers…and neither are the mufflers on the type 3 as many erroneously believe and quote.

2. They are effectively part muffler..…using bypasses/baffles and directional changes to lower exhaust energy and de-tune sound energy..…and part resonator (a larger part resonator than pure muffler)….with different sized chambers to dampen different frequency ranges.

Resonators…when designed properly actually get rid of the frequencies that can resonate or “hum” or “drone” through the entire chassis at specific rpm ranges…..but without a lot of baffling or energy losses.

Typically a lot of the WC VW cars and others would use a resonator upstream of the muffler. It allows a much more quiet system by dampening certain resonant frequencies upstream to prevent having to make the muffler overly restrictive downstream.

3. As Jake Raby has noted in posts a long time back on the STF and others (including myself) found out long ago…..the stock muffler design runs engines HOT HOT, HOT. What is inside shows just why the engines and/or specific cylinders or pairs of cylinders run hot with these type of mufflers at the same time as being very quiet considering what they are and what little is in them.

NOTE: There was also extensive heat erosion damage to one of the primary pipes inside. I thought the damage happened when I blew the engine because I heard parts rattling around inside……and the final damage may have…..but really it’s very evident that the cylinder 1-2 side header inlet pipe was so heat damaged that it was literally cracking all over. Part of this is because it is so tight in this muffler that the inlet Y pipe was hard up against the muffler outflow pipe. It could not cool and was probably red hot all the time.

You will see this in the pictures.

I will have some general views first…then a diagram at the end to show the general layout and gas flow path.


The pictures of each chamber will show an straight on view and then a view from a lower angle…eight pictures in sequence so you can get oriented because from any one angle a lot of stuff is hidden by pipes in front of it.

In these pictures the left side of the muffler with cylinders 3 and 4 will always be on the left and the starting point….left to right looking toward the front of the vehicle…with tailpipe exiting to the right and the cylinder 1 and 2 side.

So…The muffler in question:

Image may have been reduced in size. Click image to view fullscreen.

Image may have been reduced in size. Click image to view fullscreen.


The orange things are silicone rubber sheet seals under muffler gaskets to seal the muffler to check the volume with water.

Image may have been reduced in size. Click image to view fullscreen.


Made in October of 1991

The basic muffler layout:

This is a four chamber muffler. From left (driver side) to right- you have what appears to be:

1. Basically an 11” long volume/pressure chamber that is fed by the exhaust from both cylinder banks after it comes through a short resonation chamber. This chamber dumps into the farthest end of the final exhaust pipe.

2. A short 3.5” long and 6” diameter chamber that has a large though hole from the center mixing chamber from both banks. It’s outlet from this chamber to allow it to go into the open end of the final exhaust outlet pipe is 85 .125” holes in the baffle plate which equal 1.02 sq. inches of open area and 84 .125” holes in the final exhaust outlet pipe which equals another 1.00 sq. inches of open area.

3. The main center mixing chamber which is 11” long and 6” diameter with a large depression to clear the breastplate of the engine sheet metal. The combined header pipe from cylinders 3 and 4 dump into this area from the left and the combined header pipe from cylinders 1 and 2 dump in from the right facing right at each other about 8” apart.

The only outlet from this chamber (for all of the exhaust) is the through hole in the baffle to the left which is 1.85” in diameter for 2.69 sq. inches of area….into the small 3.5” long baffle chamber described previously.

NOTE: so to recap at this point all of the exhaust from all four cylinders enters into the center chamber, exits through a 1.85”diameter hole into a resonance chamber of 3.5” long by 6.0” diameter which is about 99 cubic inches in volume. The only exit from this small chamber is 169 holes of .125” diameter which equal 2.028 square inches of opening…..that allow this exhaust into the first chamber listed whose only exit s the final exhaust pipe which has an opening of 1.70” diameter.

4. The fourth chamber is a closed/dead end chamber…. purely a resonance chamber and volume or gas velocity reducing chamber. This chamber is 11” long and 6” diameter. The inlet pipe from cylinders 1 and 2 pass through this chamber but does not vent into it and the main final exhaust pipe passes through it on its way out and vents into this chamber through 735 .125” perforations and the perforated area is wrapped with coarse steel wool.

This chamber allows a portion of the final exhaust to vent into it, creating a pressure head to damp pulses. The steel wool increases the surface volume of the chamber lowering some of the gas velocity.

Image may have been reduced in size. Click image to view fullscreen.


Image may have been reduced in size. Click image to view fullscreen.


This is the first chamber on the left showing inlet pipe from cylinders 3 and 4 and the opening into the final exhaust pipe and the array of 85 perforations for exhaust gas inlet into this chamber.

Image may have been reduced in size. Click image to view fullscreen.


Image may have been reduced in size. Click image to view fullscreen.


The is the second chamber from the left showing the left hand baffle you saw in the photos above, the other set of 84 perforations in the final exhaust pipe that allow some inlet into the pipe from this chamber as well. You can also see the through hole in the right hand baffle for exhaust inlet from the center or main mixing chamber.

Image may have been reduced in size. Click image to view fullscreen.


Image may have been reduced in size. Click image to view fullscreen.


This is the center chamber or main mixing chamber. Note the heard pipes coming in from left (cylinders 3 and 4) and right (cylinders 1 and 2), the through large hole into the baffle chamber at left…and the crimped restriction in the final exhaust outlet pipe that is passing through. I can only guess that this is tuning to keep pressure higher in the first chamber at the far left and also maybe to keep exhaust gas velocity higher in the downstream section of the pipe……or it may create a low pressure area downstream of this restriction like a venturi. I just don’t know.

Image may have been reduced in size. Click image to view fullscreen.


Image may have been reduced in size. Click image to view fullscreen.


This is the final chamber to the right. The only inlet into this chamber is also the only outlet.
After doing some reading, this is a classic resonator design. Some gasses exit the final exit pipe into this chamber through the 735 perforations. As impulse pressure builds and subsides from exhaust pulses…the gas pressure alternately lets some gasses in and out.
This alternating pressure differential creates both a “pneumatic” cushion and alternately cancels some of the exhaust/sound energy. Added to this is the fact that this perforated section was wrapped with a double wrap of course straight fiber stainless steel wool/fiber. This acts like classic muffler packing to increase volume area and slow down gasses.

Image may have been reduced in size. Click image to view fullscreen.


A view of the stainless steel fiber before it was cut away. You can see that over time it was pushed out of the way.

Image may have been reduced in size. Click image to view fullscreen.


A looking back along the length view.

Image may have been reduced in size. Click image to view fullscreen.


Here is the damage. Note the red arrow. Note that you can see daylight back through the inlet flange from the header. The entire seam and about ½” of metal was literally eroded/burned away allowing the exhaust from the cylinder 1 and 2 header pipes to invade this chamber.

The muffler had gotten louder over the months before the engine blew and had some noticeable poor tuning effects. I knew there was something up on the cylinder 1 and 2 side. It was running hot.

As a historical note:…the exhaust had nothing to do with the engine destruction. The engine died from loss of thrust bearing flange at the cam and not enough clearance from the oil pump nuts to survive it. It hammered a bolt head loose from the camshaft and that bolt head stripped all of the teeth from the cam.

To help you get your head wrapped around the exhaust flow in this muffler I made a couple of cheesy diagrams:

Image may have been reduced in size. Click image to view fullscreen.


This cutaway shows the general layout and what pipes or perforations go through each baffle into each chamber.

Image may have been reduced in size. Click image to view fullscreen.


This is a gas flow diagram.

There are numerous issues with these types of mufflers…performance wise…and the problems are the main reason why they run so hot and are fairly restrictive:

1. The wrong cylinders are paired at the ends of the header pipes. For a four cylinder engine is a basic Tri-Y system into a resonator…one would pair cylinders whose ignition points (and therefore exhaust) are 180* apart. This would be 1 and 3 and 2 and 4. Instead…..we see 1 + 2 and 3 + 4 paired out of packaging convenience. Tough decision.

2. The primary exhaust tubing lengths are very short. Most exhaust calculators I have found….when I plug in the cam numbers and displacement…..note that the primary tubing lengths…meaning from exhaust port to collector …should be between 48”-52” for our rpm/peak torque band.

The longest primary tube lengths are for cylinders 1 and 3 and are about 34” total.

3. This leads to the last problem that the primary pipes for cylinders 2 and 4 are about 7” shorter than those for cylinders 1 and 3.

Interestingly….the calculators I have tried….note that the tubing diameters are spot on in this muffler. We don’t really have secondary pipes as this is mainly a resonator…..but you could work the volume of the center mixing chamber into that train of thought.

So….we have: Unequal primary tubing lengths, short primaries and improper cylinder pairings.

Some things to think about.
Ray
Back to top
View user's profile Send private message Gallery Classifieds Feedback
Lars S
Samba Member


Joined: October 04, 2007
Posts: 544
Location: Sweden
Lars S is offline 

PostPosted: Mon May 02, 2016 11:28 am    Post subject: Re: Ernst 411-412 muffler cross section and dissection Reply with quote

Intresting Ray!
I had no idea there was so much theory built in the stock mufflers...thanks for the examination!

Lars S
_________________
Porsche 914 -72, Bahia Red daily driver Smile
VW411 2-d -70, White, sold Sad
VW412 4-d, -73, Gold Metallic, daily driver
Suzuki T500, -69, Candy Gold, sold Sad
Suzuki K50, -77, Black, daily driver
BMW R69S -69, White, sold Sad
Husqvarna 118cc, -47, Black, in archive
Back to top
View user's profile Send private message Classifieds Feedback
raygreenwood
Samba Member


Joined: November 24, 2008
Posts: 14847
Location: Des moines Iowa
raygreenwood is offline 

PostPosted: Mon May 02, 2016 11:54 am    Post subject: Re: Ernst 411-412 muffler cross section and dissection Reply with quote

Lars S wrote:
Intresting Ray!
I had no idea there was so much theory built in the stock mufflers...thanks for the examination!

Lars S


Yes. It's really not something we can beat on VW for.....the hot running and restriction of this muffler/exhaust system....when you take into account that the ACVW engine is noisey compared to modern water cooled engines and exhaust systems.....but really is amazingly quiet compared to how noisey we know it COULD be.

And.....though the muffler obviously is not a performance oriented product.....it allows these engines and cars....designed partly around the exhaust system and vice versa......to operate within design parameters for quite a long time.

And.....the packaging problem VW had to simultaneously solve....was HUGE. How to cram the required level of silencing effect, a survivable level of exhaust length and back pressure ....and some level of serviceable simplicity ....into a allowable space that is roughly 6" in diameter (not including the depressions in the muffler for the breastplate and dipstick tube) and 36" long.

There is a LOT of exhaust tuning design inside of these.....but also a lot of compromises. ...mostly made for space constraints.

I found a really good infomercial article with segments from some of the top performance muffler/exhaust builders in the industry. ...about how all of these different types of tuning devices work. I will post later. Ray
Back to top
View user's profile Send private message Gallery Classifieds Feedback
KTPhil Premium Member
Samba Member


Joined: April 06, 2006
Posts: 24527
Location: Conejo Valley, CA
KTPhil is offline 

PostPosted: Mon May 02, 2016 1:12 pm    Post subject: Re: Ernst 411-412 muffler cross section and dissection Reply with quote

Ray, I think the basis of the claim about the Type 3 muffler being a header is the internal plumbing that equalizes the length of the pipe runs before they feed the open muffler chamber, as shown below.

Image may have been reduced in size. Click image to view fullscreen.


Image may have been reduced in size. Click image to view fullscreen.


The little perforated cones come from the front cylinders, which have the main heat exchanger flow path ahead of them. The aft cylinders have a very short path through the small HEs, and then go through the long internal pipes.

While it's probably an overstatement to call it a header (due to the lack of normal merging), but it does seem to have a lot of thought put into it regarding resonances, which is one of the main advantaged of a tuned equal-length header. Many people assume its little more than a can but it is an exhaust SYSTEM enclosed in a can.

I see the Type 4 is very different, but shows the same attention to path length and resonances.
Back to top
View user's profile Send private message Gallery Classifieds Feedback
raygreenwood
Samba Member


Joined: November 24, 2008
Posts: 14847
Location: Des moines Iowa
raygreenwood is offline 

PostPosted: Mon May 02, 2016 1:49 pm    Post subject: Re: Ernst 411-412 muffler cross section and dissection Reply with quote

KTPhil.....yes.....I have seen that set of pics.

Just like the type 4 muffler...as you note....it shows that a lot of thought went into it. At the very least.....they worked hard with the type 3 muffler to equalize volumes per side.

It also suffers from some of the same problems....or compromises actually. Really the type 3 actually has a much bigger issue with primary header tube length being asymmetrical than the type 4 muffler......
But......it also has much better volume symmetry from side to side....being almost mirror imaged....and appears to have the cylinders paired correctly which is why the large pipes traverse from side to side.

I actually learned a bit of useful info toward working on my own design a while back when I saw these pictures.

The perforations are a method of slowing down gas velocity by forcing the volume through a series of orifices that are smaller....but should work out to close to or greater opening area than the tube diameter they are coming from.
The other pipe.....in the center is largely a balance pipe pushing impulse back and forth to cancel frequencies. Also the type 3 muffler does a LOT less directional changing or switchback of gas than the type 4 muffler.

Thats one of the things I am working toward in the muffler I am making is one main directional change of only 90° instead of 180° with the gasses coming out of the header pipes....feeding into proper Y's before entering the final pipe.

Hence....though the type 3 muffler may limit HP and torque production a bit more.....it runs cooler from my memory and is even more quiet than the type 4 muffler in general. Ray
Back to top
View user's profile Send private message Gallery Classifieds Feedback
titan3c
Samba Member


Joined: February 16, 2012
Posts: 382
Location: Coweta, Oklahoma
titan3c is offline 

PostPosted: Mon May 02, 2016 2:10 pm    Post subject: Re: Ernst 411-412 muffler cross section and dissection Reply with quote

Just a curious question about the type 4 muffler installation. I notice the sedans exhaust to the left, and the Variants exhaust to the right. Is there any particular reason for that? I know the heater exhaust is on the righ

I replaced the muffler on my sedan with a right exhaust some years back, and I have a spare I've had for some time which is also a right exhaust. A little off the subject, but I've always wondered.

BTW I just checked my spare muffler for mfg name, but there is no mfg identification anywhere on it. Bob
Back to top
View user's profile Send private message Classifieds Feedback
raygreenwood
Samba Member


Joined: November 24, 2008
Posts: 14847
Location: Des moines Iowa
raygreenwood is offline 

PostPosted: Mon May 02, 2016 2:37 pm    Post subject: Re: Ernst 411-412 muffler cross section and dissection Reply with quote

titan3c wrote:
Just a curious question about the type 4 muffler installation. I notice the sedans exhaust to the left, and the Variants exhaust to the right. Is there any particular reason for that? I know the heater exhaust is on the righ

I replaced the muffler on my sedan with a right exhaust some years back, and I have a spare I've had for some time which is also a right exhaust. A little off the subject, but I've always wondered.

BTW I just checked my spare muffler for mfg name, but there is no mfg identification anywhere on it. Bob


They have versions that exit to both right and left on all models. In fact.....I have never seen anything but a right exit or a center exit to the right in the US. Does not mean that there have not been left exits here in the US....just that they are few.

I think Lars or someone else posted a thread a while back about the fact that some early 411 had left exit heaters for a particular reason and there was a good amount of info about exhaust in there as well.
I will look in thr parts book and see if there are any M codes or country codes that apply to this. Ray
Back to top
View user's profile Send private message Gallery Classifieds Feedback
raygreenwood
Samba Member


Joined: November 24, 2008
Posts: 14847
Location: Des moines Iowa
raygreenwood is offline 

PostPosted: Mon May 02, 2016 6:12 pm    Post subject: Re: Ernst 411-412 muffler cross section and dissection Reply with quote

Since we are talking about it...or at least I am....I will throw in some sketches of how I plan to make a muffler for my 412.

Bear in mind ....I could be really happy with the better flow and lifespan of say...A VW Heritage stainless steel T-bird header knock-off like this one

https://www.vwheritage.com/shop/bay-bus/AC251704/s...StartRow=1

And it would be dirt simple to bolt up....and even with shipping the price is not bad...but I can guarantee you that this will be a tight ugly fit behind the rear "cheese grater" fence of my 412. My four door had a T-bird with a glass pack on it when I bought it. Ran great...loud as hell.

Or this one from Vintage speed: http://shop.vintagespeed.com.tw/s.nl/it.A/id.73/.f

or this one which will NOT fit behind the rear fence...but lists higher flow.

http://shop.vintagespeed.com.tw/s.nl/it.A/id.120/.f

which I can guaratee will have fit issues on the 411/412...just by looking at it. It lacks the 1" deep dish for the breast plate....but I could work with that ...but am not thrilled at the possibility of having to bend sheet metal.

Also....I found a sketch of a cutaway of one of these a while back I will look for and post....its very well designed inside....but like the rest...are not equal length...is a bypass/baffle style muffler...and I have not found any data to suggest that other than having larger volume which should help....that its not any more or less restrictive than any of the stock styles.

While having a muffler in stainless is one of the prime decisions makers behind all of this...for the price...and for my car...THE PRIME decision maker is better engine longevity...for me.

This is a really interesting article with a lot of active and passive silencing and exhaust flow techniques. A good read.

http://www.dragzine.com/tech-stories/exhaust/under...rategies/.

More later when I get my sketches done. Ray
Back to top
View user's profile Send private message Gallery Classifieds Feedback
furgo
Samba Member


Joined: September 06, 2016
Posts: 795
Location: Southern Germany
furgo is offline 

PostPosted: Tue Jul 03, 2018 6:23 am    Post subject: Re: Ernst 411-412 muffler cross section and dissection Reply with quote

I came across this excellent thread as it was mentioned recently on the Bay Window forum. Great work as usual.

I've got a somehow related question... I believe my bus has a Dansk muffler, but I couldn't find any info on it. Ray, what are the markings on that NOS Dansk one you mention you have? Perhaps I can compare mine with them. Even if it's a different part for a bus, the part numbering scheme should be similar (I'm guessing the "DK" stands for Dansk).

Mine read:

52 04551
DK 81-334-378
13 03

Image may have been reduced in size. Click image to view fullscreen.

Image may have been reduced in size. Click image to view fullscreen.

_________________
'79 Westy, P22 interior, FI 2.0 l Federal, GE engine (hydraulic lifters)
Back to top
View user's profile Send private message Gallery Classifieds Feedback
raygreenwood
Samba Member


Joined: November 24, 2008
Posts: 14847
Location: Des moines Iowa
raygreenwood is offline 

PostPosted: Tue Jul 03, 2018 11:35 am    Post subject: Re: Ernst 411-412 muffler cross section and dissection Reply with quote

Furgo...you always open a delightful can of worms!

The mufflers...... Very Happy

So....from my experience and your markings....you have....a Dansk....Uh..Walker...Uh Starla....uh....all of the above! Laughing

So check out these pictures of my NOS muffler ....which by construction and the mediocre quality of the welds and the flange materials and the markings...the part # DK 81-334-378...I "think" is a Dansk part #....so it "seems" to be a Dansk in my opinion.
Image may have been reduced in size. Click image to view fullscreen.

This muffler seems to be a Dansk in construction...but has a Wagner metal stamp....and a Starla decal...

Image may have been reduced in size. Click image to view fullscreen.

and...you can just see the Wagner logo decal under the Starla decal.

Image may have been reduced in size. Click image to view fullscreen.


Image may have been reduced in size. Click image to view fullscreen.

Classic Dansk messy welds and stamped pattern flanges on the inlet and outlet flanges. Compare how restrictive these seem to the Leistritz muffler pictures below.

So which is it really?

Well Read this link.
https://en.wikipedia.org/wiki/Tenneco

The gist.... Tenneco....bought Walker in 1969. Walker was one of THE MOST innovative muffler company's ever.
They invented the louvered noise reduction pipe (resonator)....invented the first stainless steel exhaust system parts...invented the first catalytic converter and mass produced it. Stellar mufflers...back in the day.

So Tenneco bought Walker...and in 1974 they bought Starla...a high quality Swedish muffler manufacturer serving mostly Europe. So they had a network now. From what I can surmise....American made Walker products were sold under the Starla name in Europe...and probably Swedish made products sold in the US under the Wagner name....or....its possible that owning both names and companies they simply grouped all imported exhaust system parts under Starla and all domestic under Wagner. I just do not know.

But...for some time....Dansk has been owned, or a part of JP group....Jopex....Johannes Petersen

http://en.jpgroup.dk/company/the-history-of-jp-group.aspx

So I am "guessing" that the conglomerate of Tenneco...AKA the parent company of Walker since 1969...and later Starla....was buying certain parts made regionally to include parts from Dansk/Jopex.

The other exhaust I have for comparison of quality to the Dansk/Wagner/Starla I showed above.....is an NOS OEM Leistritz for a 411 E (damper style center exit) made in "Nurnberg" (Nuremberg) in May of 1973......which goes against the statement of some in the thread below who think that Leistritz was only in the VW parts business since 1975.

Image may have been reduced in size. Click image to view fullscreen.

May 1973 build and you can see the Leistritz logo in the red circle.

Image may have been reduced in size. Click image to view fullscreen.

Image may have been reduced in size. Click image to view fullscreen.

Much higher quality welding and metal.

https://www.thesamba.com/vw/forum/archive/index.php/o-t--t-613681--.html

Some nice video history here in these links
https://www.leistritz.com/en/company/history.html
https://tools.leistritz.com/en/company/history.html

Ray
Back to top
View user's profile Send private message Gallery Classifieds Feedback
furgo
Samba Member


Joined: September 06, 2016
Posts: 795
Location: Southern Germany
furgo is offline 

PostPosted: Tue Jul 03, 2018 2:23 pm    Post subject: Re: Ernst 411-412 muffler cross section and dissection Reply with quote

Thanks Ray. I think from that I conclude that I have a Dansk muffler indeed. It seems that the two first rows of the stamped numbering are the same.

The only differences being:
- the third row, which in my case I had always thought was the production date. Looking at the number on your muffler, I no longer think so.
- no Walker stamping on mine. Perhaps it indicates a part sold in Europe? For some more context on the origin of parts, mine is a tourist bus that lived some years in the US before coming back to Europe around the 90s.

I can't definitely tell from the pictures, but yours seems painted, while mine is galvanized.

raygreenwood wrote:
Furgo...you always open a delightful can of worms!


I see your can and I raise you a bucket! Here's some more research in return, as a way of thanks:

Here's the current muffler from the Jopex brand:

Image may have been reduced in size. Click image to view fullscreen.


Their current Jopex part number is 8120601900
http://www.jpgroupclassic.com/productview.aspx?ID=8120601900

Their former Dansk part number was VW-35028. Jopex is the current brand for VW parts from JP Group Classic Line. Dansk is now their brand for Porsche instead. I'm not sure when this change happened, but I guess that's why I couldn't find any info at all under the supposedly Danks part number stamped on my muffler.

The product page above points to a TÜV document for the product certification of the part for German roads. Here's the direct link:
http://www.jpgroupclassic.com/Images_products/RelatedFiles/VW-35028.PDF

A few comments on that:

• If you look at the first extract of that document below, you'll notice that the muffler has or had either a Dansk or Walker marking. So it might have been an original Walker design.
• If you look at the second extract, you can actually see the insides of the muffler. It might spare you the effort of sectioning your muffler –although I for one would still be interested to see how the insides and their quality compare to the stock one Smile
• This Jopex/Dansk/Walker uses basalt rock wool instead of stainless steel wool. I'm not sure if that's indicative of better/worse/equivalent quality.
• In case this has any particular meaning, the drawings are from 1991. I'm not sure if the part was manufactured earlier, probably yes. There was an addendum in 2008, just to include the assembly instructions. I would think the currently available part has not changed since then.

Image may have been reduced in size. Click image to view fullscreen.

Image may have been reduced in size. Click image to view fullscreen.


Rougly translated legend from Danish:

1 - Muffler top
2 - Muffler top part
3 - Basalt rock wool (long fiber)
4 - Tailpipe
5 - Perforated pipe
6 - Central tube
7 - Bulkhead A
8 - Bulkhead B
9 - Bulkhead C
10 - Inlet pipe
11 - Inlet pipe
12 - Inlet manifold
13 - Outlet flange
_________________
'79 Westy, P22 interior, FI 2.0 l Federal, GE engine (hydraulic lifters)
Back to top
View user's profile Send private message Gallery Classifieds Feedback
raygreenwood
Samba Member


Joined: November 24, 2008
Posts: 14847
Location: Des moines Iowa
raygreenwood is offline 

PostPosted: Tue Jul 03, 2018 3:25 pm    Post subject: Re: Ernst 411-412 muffler cross section and dissection Reply with quote

Yes....it looks virtually identical in the inside layout to the Ernst I cut open. Thank you!

The one I really want to see inside is the "damper style" center exit model of exhaust. But the Leistritz is such a high quality model....I refuse to cut it up.

Jopex/Dansk also still has a normal catalog for VW and other models.
http://www.jpgroupclassic.com/products.aspx?brand=3

They just have a distinct catalog for Porsche because they make body panels and parts as well. Ray
Back to top
View user's profile Send private message Gallery Classifieds Feedback
KTPhil Premium Member
Samba Member


Joined: April 06, 2006
Posts: 24527
Location: Conejo Valley, CA
KTPhil is offline 

PostPosted: Tue Jul 03, 2018 3:38 pm    Post subject: Re: Ernst 411-412 muffler cross section and dissection Reply with quote

raygreenwood wrote:
The one I really want to see inside is the "damper style" center exit model of exhaust. But the Leistritz is such a high quality model....I refuse to cut it up.


For other reasons (plugged yard drains, not do-it-yourself colonoscopy) I bought this borescope for about $50:

https://www.amazon.com/gp/product/B0785H3XR7/ref=oh_aui_detailpage_o06_s00?ie=UTF8&psc=1

This may let you explore the inside of the muffler enough to figure out what's inside. Handy for other hard-to-see inspections, too (screws dropped into carbs/combustion chambers, behind-wall cable runs and plumbing, drains, drier vents, A/C vents, etc.)

This version has a really long cable, and connects wirelessly to your phone (careful, there may be different versions for different phones) and it records stills and movies. I like the wider depth of field this one has.
Back to top
View user's profile Send private message Gallery Classifieds Feedback
furgo
Samba Member


Joined: September 06, 2016
Posts: 795
Location: Southern Germany
furgo is offline 

PostPosted: Tue Jul 03, 2018 4:03 pm    Post subject: Re: Ernst 411-412 muffler cross section and dissection Reply with quote

Something else to add to the original post... I just noticed that the Ernst muffler is still available, and at a very affordable price.

I'm assuming it's the same design with a different part number:

=> Ernst 104005

Image may have been reduced in size. Click image to view fullscreen.


If that's what used to be the stock one, that's the one I'll probably look at when I have to replace my muffler.

Also, for those concerned about noise (I am) the Jopex muffler has some dB figures on the TÜV report:

Driving vehicle*

• Aftermarket: 79 dB
• Stock: 79 dB

Stationary vehicle*

• Aftermarket: 91 dB
• Stock: 91 dB

These probably also apply to the Ernst one.

* Measured at 3450 RPM
_________________
'79 Westy, P22 interior, FI 2.0 l Federal, GE engine (hydraulic lifters)
Back to top
View user's profile Send private message Gallery Classifieds Feedback
raygreenwood
Samba Member


Joined: November 24, 2008
Posts: 14847
Location: Des moines Iowa
raygreenwood is offline 

PostPosted: Wed Jul 04, 2018 10:07 am    Post subject: Re: Ernst 411-412 muffler cross section and dissection Reply with quote

Having driven with all of them at one time or another.....I can tell you that the Dank/Jopex and the Ernst and The Leistritz...all end exit models....are approximately the same in sound level....but they have noticeably different exhaust note.

The Dansk....is slightly higher pitched...and is a little more restrictive (more on that in a minute).

The Leistritz version which was a stock dealer available muffler is teh classic stock sound and noise level. The Ernst was about the same LEVEL of sound but was slightly deeper in pitch and had a unique sound on deceleration/over run. It "sounded" like it flows better...and in fact it tunes like it as well.

I know teh Dansk is more restrictive. You can see this just in the diameter of inlet and outlet ports...which are the only part I "know" for sure are more restrictive.....except that it IS slightly smaller in total volume by a few liters....which is why I really want to look in side one to see what the perforation hole size and quantity it.

From what I can see looking into the exit pipe of all three....the Ernst has slightly larger holes in the perforations which explains the sound note difference and may explain part of the lower restriction.

I know the Dansk is more restrictive...and the Leistritz slightly less restrictive than the Dansk...and the Ernst less restrictive than either....because I was installing these on a HIGHLY tuned 412. You may not notice the difference on a bus.
But on a 412 that is highly tuned with a four speed trans.....it requires a change in fuel mixture going from the Ernst to a Dansk....and almost always a slight idle adjustment as well.

The center exit exhaust (damper style)...are THE most restrictive. Even slightly more restrictive than the Dansk.....but very quiet. Ray
Back to top
View user's profile Send private message Gallery Classifieds Feedback
Towel Rail
Horizontally Opposed


Joined: April 15, 2005
Posts: 4560
Location: SE CR IA US NA PE
Towel Rail is offline 

PostPosted: Sun Jul 08, 2018 5:50 pm    Post subject: Re: Ernst 411-412 muffler cross section and dissection Reply with quote

This is a fantastic thread, Ray. Although I am unlikely to own a Type IV car, or perhaps even a Type IV-powered car, your threads on dissecting and blueprinting these parts are illuminating. I also didn't realize you lived so close to my area -- did you move in the last few years?

Would it be premature to ask what ideas you have for improving the stock muffler in your design? Given space limitations above, in front of, and behind the stock muffler, would you extend it downward to gain more volume? (Meaning space, not sound.) Wink
_________________
1974 Thing -- under the knife
1967 Beetle -- spring/summer/fall driver
1996 Subaru OBW (EJ22, 5-speed, AWD) -- winter car, 3-seasons "don't feel like biking today" car

049 > 070 > 053 > 009
Back to top
View user's profile Send private message Gallery Classifieds Feedback
raygreenwood
Samba Member


Joined: November 24, 2008
Posts: 14847
Location: Des moines Iowa
raygreenwood is offline 

PostPosted: Mon Jul 09, 2018 12:47 pm    Post subject: Re: Ernst 411-412 muffler cross section and dissection Reply with quote

Towel Rail wrote:
This is a fantastic thread, Ray. Although I am unlikely to own a Type IV car, or perhaps even a Type IV-powered car, your threads on dissecting and blueprinting these parts are illuminating. I also didn't realize you lived so close to my area -- did you move in the last few years?

Would it be premature to ask what ideas you have for improving the stock muffler in your design? Given space limitations above, in front of, and behind the stock muffler, would you extend it downward to gain more volume? (Meaning space, not sound.) Wink



The space limitations are the killer!

So we have all heard of the better effect that a basic "Thunderbird" style 4 into 1 header can make....right?

But I have also heard...and I can see this....that though the basic "T-bird" style header is an improvement over the stock muffler in flow....it has issues. Its not really a proper header with nice inlet angles and does not have exact equal length pipes. Its just a header that has been beaten into shape to fit in a tight spot.

Image may have been reduced in size. Click image to view fullscreen.


Image may have been reduced in size. Click image to view fullscreen.


This is teh basic thunderbird design but done in stainles from VW Heritage...which I think is the same as EMPI

And....that collector flange is a BIG hole....and has no real merge or collector space between it and the muffler inlet...so while it is an improvement in flow over the stock muffler...it is nowhere near as much benefit as a real tuned header with a proper muffler would be. It can have flat spots in certain ranges because of that large dead space right after all the pipes merge.

And..depending on rpm band and gearing and cam and lots of things.,..you can get arguments especially in the case of 914....for using a 2 into 2 into 4 like the Bursch header....which is well tuned...but will not be anywhere near fitting under a 411/412. Probably no problem on a 914 or a bug when you can let some of it hang out.

Image may have been reduced in size. Click image to view fullscreen.

This is the Bursch 2 into 2 into 1 header.

So keeping mind that overall we are happy with the stock muffler in a sound dampening point of view......if we could change just one or two things...we can get better performance from it.

Right away as noted the Ernst...just by using a marginally larger muffler in overall dimensions.....got larger internal volume. It has largely the same internal chambering and layout as the Dansk and any other end exit type 4 muffler....but has slightly larger perforations in the main exit pipe...probably a few more perfs in one area or another...but its main thing is that when you measure the outside of the muffler body in a lot of areas.....it a few millimeters larger...most everywhere. Not enough to make a fit issue anywhere....but just enough to give a larger internal volume overall.

And....I know from experience these changes actually made an improvement. Whether its the pipe size, the perf size the extra volume...or all combined.....that make the improvement....I do not know yet.

But...to the original question....if we were making a further improved replica of the original muffler.....what could we do?

Lets say we just wanted more volume. So....as you note...the first thing I would do is just keeping the inside layout and chamber size allocations identical....yes....I would increase the outside diameter by a bit...and since you cannot move upward....I would move downward. If you have the ability to form sheet metal....you could keep it squarish in cross section with rounded corners....and get away with lengthening its height downward by maybe 3/4" ...just so its peeking out from below teh rear skirt...and you could probably get maybe 10mm closer to the bolt on rear valance skirt and still not have issues.

For example just in a very gross calculation.....if you are looking at the stock muffler overall outside size and doing a volume change.....lets say the stock muffler is roughly round in cross section and is 6" diameter and 40" long.

That is a crude calculation of about 1,131 cubic inches. If we can increase the overall diameter by only 1/4"....it increases the volume to 1,227 cubic inches....and that is just about an 8% increase.

Ok...but the stock muffler is NOT actually really round....its kind of a roundish rectangle because of the way its made in two welded parts.

So lets say we actually drop it down 3/4"...so we can take out those damn dent in the top for the breast plate clearance and the oil dipstick tube. We can pick up about about say 1-2% volume that way....and we make this thing out of an actual TUBE of metal....that can be larger in diameter by up to say 3/4".....which is only 3/8" on any/all directions.

That is a whopping 21% increase in volume over stock.

And...I think that is a lot of the benefit of the Vintage speed muffler. The vintage speed is not equal length...its not a header....though from pictures I have seen its mainly a combination of a chambered bypass muffler and resonator. And is basically round tube construction.
Image may have been reduced in size. Click image to view fullscreen.


My hesitation with simply buying a vintage speed is that I have seen no information about how it runs with a stock sized engine with stock injection.

I want equal lengths for equal heat and pressure on the primary lengths. I think there is already enough potential imbalances in the system. I would hate to have overall less back pressure and higher volume in the system...which can run better...but still have unequal exhaust pressure and cylinder temps on all cylinders.
Ray
Back to top
View user's profile Send private message Gallery Classifieds Feedback
Display posts from previous:   
Reply to topic    Forum Index -> 411/412 All times are Mountain Standard Time/Pacific Daylight Savings Time
Page 1 of 1

 
Jump to:  
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum

About | Help! | Advertise | Donate | Premium Membership | Privacy/Terms of Use | Contact Us | Site Map
Copyright © 1996-2018, Everett Barnes. All Rights Reserved.
Not affiliated with or sponsored by Volkswagen of America | Forum powered by phpBB