Bostig Muffler Options with Catifold

[john_lessard]

Fellow Bostig owners:

Seems the Walker 21141 is discontinued and a replacement option needs to be identified. I've had the 21141 installed on my van for about 4000 miles now and the droning at highway speeds is getting to me. I figured this would be a good time to test a replacement. Here are Jim's words from a post on the Zendesk Support page:


"
The Walker 21141 looks like it's been discontinued. Luckily the exhaust hanger setup makes replacement with alternatives very flexible as long as the overall dimensions, inlet/outlet configurations and sizing are consistent. I'll be testing another more recent walker quietflow shortly, and hopefully it can become the "standard" muffler, but here are part numbers and info I've collected below in the meantime:



Old muffler: Walker 21141

Application 96-00 Ford Contour 6 cylinder

Muffler Material: Steel

Case Shape:Oval

Inlet Diameter (in.):2.000 in.

Inlet Quantity:One

Inlet Location:Offset

Outlet Diameter (in):2.000 in.

Outlet Quantity:One

Outlet Location:Offset

Reversible:No

Internal Construction:Turbo-style

Muffler Finish:Aluminized

Case Exterior Length (in.):12.000 in.

Overall Length (in):21.000 in.

Thickness (in.):5.500 in.

Width (in.):11.000 in.



Direct replacements (correct sizing, may be louder than the quietflow):

AP / EASTERN 700239 MSL/MAXIMUM; Aluminized Steel Info

WALKER 18808 SoundFX;



Possible replacement quietflow(test results in July 2021):

Walker 21525 Quiet-Flow Stainless Steel Muffler




Universals that should fit, but need tips, untested.

AP / EASTERN 3779 Enforcer II; Oval Body; H4.25" X W8.75" X L13"; 17" Overall Length; 2" ID Configuration. O/C

AP / EASTERN 690008 Xlerator Big Max Turbo; Small Oval Body; H3-1/4" X W7-3/4" X L11"; 16" Overall Length; 2"

WALKER 17904 16.5" OAL

WALKER 17900 18" OAL

WALKER 17188 SoundFX; Aluminized Steel; 17" OAL

WALKER 17815 SoundFX; Aluminized Steel; 18.5" OAL

AP / EASTERN 690003 Xlerator Big Max Turbo; Small Oval Body; H3-1/4" X W7-3/4" X L11"; 16" Overall Length; 2" O/O
"


I purchased the Walker 21525, with the hopes the Quietflow solves the droning issue. I test fitted it on my 2WD. For reference I am running 215/75R15 tires.

The muffler sits closer to the outside of the van compared to the 21141. I re-arranged the Bostig muffler hangers to better suite the new position. It's almost perfect with my configuration. I will need to add a shim or bend a bracket to get the muffler to sit horizontal. It's about 2 inches away from the rear tire which is concerning.


Would love to hear input from others with other-than-stock mufflers before I modify this one to make it work with my exhaust!
_________________
1986 Tin-Top Vanagon, 2.0L Zetec, Peloquins TBD 2WD

[kourt]

I've been running the Walker 17904 for years. I replace it about every two years. Great fit, minimal drone---at least, less drone than any of the truly stainless options.

The world of mufflers is full of products that produce a throaty, loud sound intentionally. It's a challenge to filter out those products to find something that is designed to be quiet.

kourt

[JudoJeff]

Hi John,
Cut off the metal rod sticking off the back of the muffler.

If the muffler fits in the space, it should work.

Re-directing the sound by adding an extension to the muffler exhaust can help. They sell a vast variety. Some move the noise 90 degrees to the side, others soften the sound. Read up on how silencers work. Same principles work here.
_________________
________________________________________
1989 Vanagon GL Westfalia Camper, Burned up on 7/31/16.
1987 Vanagon GL Westfalia Camper, Bostig & Rebuilt, sold
1986 Vanagon GL Westfalia Camper, Bostig Sold May 10, 2021
1999 Ford GTRV Westfalia camper (30% bigger Westy layout)

[john_lessard]

Yes I will cut those welded hangers before final install. This was a dry fit, in case I needed to return it.

Not sure how an exhaust silencer can fit with the 45 deg angle tip.

I am hoping Jim can chime in since he may have already tested this exhaust to some extent in July.
_________________
1986 Tin-Top Vanagon, 2.0L Zetec, Peloquins TBD 2WD

[gdmike]

Any results with your muffler replacement? My Bostig has an extremely loud resonance drone similar to what you describe, especially at higher speeds. Been trying to figure out if it's intake or exhaust? I have put down layers of acoustic matting without a satisfying result
_________________
86 Wolfsburg Weekender, Bostig, Peloquin LSD, OTRA

[danfromsyr]

what does your air cleaner look like?
if it's some form of cone, visible element 'tuner type' filter that will be loud/drone on like crazy. a proper filter arrangement would have a canister/housing.

[RGS Paul]

[john_lessard]

You reached out at the right time! I continued to run the stock Walker 21141 after determining the muffler I test fitted in the first post was too close to the tires for comfort. This year the drone had finally gotten to me and I needed to fix it once and for all. Just a few days ago, I installed a Supertrapp - https://www.summitracing.com/parts/sup-444-2003.

I am a novice welder at best, but the job was very easy. There is plenty of thick metal to weld to. I cut the curved tail pipe with a Sawzall, held the flange in place, tack welded, positioned as needed, then bead welded it together.

Photos of the muffler and diffuser disks on the van coming soon.

I was able to measure a -3dB drop with an audio decibel meter in the cabin of the van at idle. The drone is significantly reduced when driving. I am absolutely delighted! Looking forward to more test driving so I can hear the difference.

[john_lessard]

Bonus muffler I test fitted for those searching:

Walker 17602
https://www.summitracing.com/parts/wlk-17602

Muffler Material: Steel

Inlet Diameter (in.): 2.00 in.

Outlet Diameter (in.): 2.00/1.75 in.

Inlet Location: Offset

Outlet Location: Center

Case Shape: Oval

Reversible: (Walker Website says Yes)

Internal Construction: Baffled

Muffler Finish: Aluminized

Case Exterior Length (in.): 11.00 in.

Overall Length (in.): 16.00 in.

Thickness (in.): 3.250 in.

Width (in.): 7.750 in.

Outlet Style: Standard, without tip


This muffler is much smaller than the 21141, but it does fit. You will just need to come up with spacers for the hangers to reach muffler when mounted and possible get shorter hose clamps. I think this could be a great candidate to pair with a Supertrapp. Its short enough that you may even be able to fit the clamp-on Supertrapp https://www.summitracing.com/parts/sup-344-2005 to save yourself some welding. I ended up returning the muffler and opting to weld my Supertrapp to my 21141.
_________________
1986 Tin-Top Vanagon, 2.0L Zetec, Peloquins TBD 2WD

[gdmike]

Thanks John, I appreciate the update!!!!! Any pics or info greatly appreciated. Going to give the Supertrapp a shot.
_________________
86 Wolfsburg Weekender, Bostig, Peloquin LSD, OTRA

[john_lessard]

Here are some photos of the Supertrapp after a ~2 hour round trip. I noticed the fuel mileage was 1 MPG down on average and I lost a bit of power in the higher RPM range. This made me think 6 disks was too little, so I added 2 more. I will continue to add disks until I'm happy with the performance / sound balance. I don't suspect to notice the different between 6 and 8 disks much.

According to the Supertrapp manual, the discoloration is normal and okay. A tan coloring to the parts is normal and a sign of an okay disk quantity.

This is not the silver bullet for the higher RPM highway drones. It definitely took the edge off, but I think I need something more. I wonder how the Supertrapp with fair paired with a different muffler. Hopefully folks can report their findings. My next noise control step is to add Mass Load Vinyl (MLV) or some recycled rubber matting to the engine bay deck through the floor. I read about others having success with that.

_________________
1986 Tin-Top Vanagon, 2.0L Zetec, Peloquins TBD 2WD

[john_lessard]

I added the rest of the Supertrapp plates to make a total of 12 plus the exhaust deflector. I also added Mass Load Vinyl covering the entire rear deck and down the slanted firewall touching the center floor. All and all I am happy with the decrease in noise. The van still drones loudly when I step on the gas. I drove it to work today and on some mild inclines on the highway I was flooring it to maintain ~60mph and the engine was just bellowing. I was actually struggling to maintain the speed too. When I floored the van in 4th gear I was nearly slowing down. I think this is normal Bostig performance. FWIW my van is a relatively light tin top, 2WD transaxle with stock gearing, and 26.3" diameter tires.

I think most of the loud drone is coming from the air intake. I have an Apollo K&N filter on my van and I think it's causing more noise and not contributing to performance. I may switch back to the stock filter to compare sound and performance changes.

_________________
1986 Tin-Top Vanagon, 2.0L Zetec, Peloquins TBD 2WD

[jimf909]

I wish we could drive each other's vans. I wonder if your noise is louder than mine or if I'm just ignoring it. I'm not bothered by my Bostig's noise and we carry on conversations in normal speaking tones. It would be nice of it was quieter. Maybe you'd say mine is just as loud? Also, yours sounds slower than mine or we have different standards for a mild incline. Mine doesn't race ip inclines but Ikm able to generally maintain 60 mph going up Snoqualmie Pass here in WA (there's a section where it may slow to 55 or so.

Regardless, as mentioned, that K&N may be contributing quite a bit of noise. Did you ask Jim for a tune for the K&N.

Thanks for experimenting.

p.s. I don't know the Walker model that I'm running.
_________________
- Jim

[john_lessard]