Bostig Muffler Upgrade

[LemonCove]

Two reasons to do this:
- Increase clearance between muffler and A/C compressor
- Reduce back pressure

Before clearance:

After clearance:

Magnaflow S/S flow through design with offset inlet/center outlet.

Full details in my Picasa album:
https://picasaweb.google.com/13VelosdeRemi/BostigMufflerUpgrade#

Jed
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'88 Bostig Westy

[plysaker]

I love it.
_________________
"Darth Blue" 1985 ASI Bostig Reemo-falia! More than the Sum of His Parts, Which are many. Curently on the rack, getting a new heart. From Ford.
"Snowball" White 1967 Franken-Fastback, a survivor's story. At least 3 cars donated to the project.

[LemonCove]

Long story short (more info on my Picasa site), I looked for a quieter, "OEM style" muffler with the same advantages of the offset design Magnaflow for A/C compressor clearance.

Here are the mufflers I researched:

The Walker rep indicated noise level would be essentially the same for all "OEM type" designs, except the "Mega Flows" which are designed for HD trucks (not a good application). All of the mufflers in the table have offset inlets and a narrower case than the "Bostig Spec" for greater clearance, and the case is short enough to fit within the same space. They all require a tip, but these are cheap and available at places like O'Reilly's and Pep Boys.

17904 Installed:

Clearance:

I actually attempted to make measurements using a sound level meter, but the meter doesn't respond like our ears do . . . there's little difference between the Magnaflow and the 17904 in db, but your ears can discern the lower, "throatier" sound. No significant difference in db when idling or cruising.

Bostig folks, I also posted on the "Knowledge Base" site.

So my advice after testing out 3 mufflers? Use an offset inlet design to give your A/C compressor more clearance from the muffler. If you want a more "OEM" sound (like the Bostig spec muffler) go with the 17904, a bargain at $20. If you want a more aggressive sound, and perhaps a minor performance benefit, go with the Magnaflow. Any installation will appreciate the Walker "acousti/seal" sealant to prevent leaks.

Lots more details on Picasa Site:
https://picasaweb.google.com/13VelosdeRemi/BostigMufflerUpgrade#

Jed
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'88 Bostig Westy

[furrylittleotter]

When I read the title I was excited to see somone had rid the system of that 90degree 0radius elbow. You can imagine my disappointment.

Neil2

[bosruten]

Thanks Lemoncove! I will surely use the information posted to change out my muffler. I have AC lines that come even closer than the compressor.
Oh.. and I've added one more person to the block list.
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'87 Syncro Weekender

[bostig]

Couple things of note:

1) Nice work and write up!
2) "SS" on the quietflow SS is marketing BS, it isn't stainless nor do they claim it, it's aluminized. But the quietest we've tested. It reaches max attenuation about 5k miles in due to soot build up on roving. They last 2-3 seasons around here. I'm game to try the other quietflow again and see how it compares though. I like a $20 pricetag
3) There is no additional benefit in terms of backpressure with going with an alternative. Even with the turbo setup the quietflow's complete removal offers no benefit or increase in flow/power. ie the muffler isn't the bottleneck even at much higher output levels. We know where the next bottleneck is, and will have some fun things later in the season if that's what you're after.


Jim

[LemonCove]

[bostig]

[kourt]

I've put the Walker 17904 on my Bostig, with a 9" down curve tip, and it's roomier and quiet, and gives more clearance from the AC compressor.

There's about 1/2" of space between the tip and the body sheet metal, and I only used one set of muffler mounts to install it. Very solid. This install eliminates the need for the machined aluminum muffler mount plate, but I'm going to leave it in place for now.

kourt

[shizzon]

Great work!

A bit off topic, but where did you get the thermal insulation on your coolant line?

https://picasaweb.google.com/13VelosdeRemi/BostigMufflerUpgrade#6001947772984575618

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1989 Bostig Syncro Westy

[shizzon]

One other question -- Has anyone re-used the exhaust flange gasket when removing and re-installing the cat, or do you have to use a fresh one every time?
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1989 Bostig Syncro Westy

[LemonCove]

[bostig]

I'm going to try the small muffler too and test for differences in flow/sound while I do it. I do like the small size a lot.

Also it should be noted that the Quietflow we spec and suggest you source through Rockauto has a lifetime warranty. So when it needs replacement you can send it in for another, or have two to rotate for that purpose. Remember that mufflers are wearable items, even stainless ones, esp. if they use wire roving and will soot up over time let alone rust/corrosion which will also occur (although much more slowly) with even the best 304 mufflers.

Jim Akiba

[kourt]

My 91 Westy Bostig conversion at a rowing regatta today. Perfect regatta vehicle. You can see the new, smaller Walker muffler here.

kourt

[westylife]

How much quieter is the smaller muffler than the kit muffler? I'm that kinda guy who wants it as quiet as possible.

WL
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1983.5 Westfalia Bostig RG1

[kourt]

With the exhaust tip installed, the Walker muffler is about the same as the stock Bostig muffler.

kourt

[denwood]

I used this way back when setting up a dual "straight thru" for my i4 conversion..may be of use today: http://www.autospeed.com/cms/A_0383/article.html

The exhaust: http://my.tbaytel.net/guskers/exhaust.html

Two SS mufflers (different sizes, both straight-thru designs) mounted inline and the CAT make for decently quiet exhaust that also performs very well.
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Cheers,
Dennis Wood
The Grape

[brooklynvan]

Here are a few pics of my install. I took the muffler to my local meinieke and they welded it in to use the old hangers.
tip on the way.
[img]https://drive.google.com/file/d/0B0ub6M12S7KmeWxVeTV6RUMydUtSVFlQdWxGMzRPYnlsN3Vj/edit?usp=sharing[/img]
[img]https://drive.google.com/file/d/0B0ub6M12S7KmWTdvZEtuMDJuV0JvRnV6RDVGWXA5VGxWNFM4/edit?usp=sharing[/img]
[img]https://drive.google.com/file/d/0B0ub6M12S7KmN01kb1dWUEJONUIzZHJac3pjNE5VQWZoSUlR/edit?usp=sharing[/img]
_________________
1990 Vanagon "Plain Jane" Bostig in the Back
TRADED: 1967 Panel for 1976 BMW 2002
SOLD: 1984 Sunroof Vanagon with EJ22
RIP 1986 Saab turbo
and my daily commuter: a Bicycle

[MsTaboo]

So..LemonCove, which muffler are you using? The Walker 17904 or the Magnaflow 12225? (12224?)

I'm in the process of rebuilding the Bostig conversion in our '90 Syncro Westy, with a zero mile engine and rebuilt A/C system. I like the idea of more clearance between the muffler and the A/C compressor.
However, in your Picasa photo album you have some conflicting info about which muffler.

Which one has given you the best performance/satisfaction?
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Currently:
'90 Syncro Westy 3 knob w/Zetec

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[LemonCove]

The 17904. Much cheaper (now $24 from Summit), and quieter. No difference in performance. I really think that's the way to go, and fits nicely.

You'll probably want to add an exhaust tip as well, for aesthetics and to clear the rear valence. I originally had a simple one from PepBoys, but when I did the burley bumper, I cleaned up the rear and added a nicer looking Vibrant Performance Exhaust Tips 1503 ($17 also from Summit.)

I also used Walker 35959 Acoustiseal to seal between the muffler and cat pipe. No Leaks.

I updated my picasa album to show the 17904, but not the new tip/bumper.
https://picasaweb.google.com/13VelosdeRemi/BostigMufflerUpgrade#
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'88 Bostig Westy