SC, Carrera Bischoff Muffler Modification, Mod, Gut, Gutting, Dual, Two Out

[75Carrera]

I added a restrictor plate option by welding in a flange where the plate can be added when I want to quite it down for long trips with a passenger... But why? It sounds so sweet!

[M Scahfer]

Gordo, got my muffler opened up and did a modified gut, just took out the pipes to the right of the middle baffle(in the picture that would be on the left of the baffle). I did some sound/video of the stock Bischoff 5/87 muffler at idle, 2000 rpm and 4000 rpm before the surgery and will do the same rpm's when the muffler is done at the welder's and re-installed.

[M Scahfer]

from the top: outlet pipe, crossover pipe, and inlet pipe.
The stock muffler weighed 20 lbs. and the pipes and third/right baffle I cut out weighed 44oz. or 2 3/4lb.

[Eric-325I]

What is the weight difference between the Bischoff (as on my '79 SC) and the average M&K?

As I don't have to deal with emissions and my original cat was most likely long ago clogged, I replaced the cat with a 'test' pipe last weekend. I can't get over how much louder the Bischoff is and sounds muuuch better as well. I can't imagine it much louder as I'm already afraid to wake up the neighborhood at night.

Eric

[911pcars]

While we're on the subject, anyone have a chance or a reason to dissect a Dansk 2in/1out or 2in/2out? Better yet, someone with photos?

Inquisitive mind wants to know.

Sherwood

[JMatta]

Yes...I have a Dansk 2 in 2 out that I'd love to know what's inside. My car is already quite loud, as I'm running headers on it (2.4 ltr).

[david dolan]

The mechanic I had when I lived in San Diego wrote the following technical article about making a dual outlet muffler. It's an interesting read.


http://www.dietersmotorsports.com/twinpipe911.htm

[stownsen914]

Quiet Boom, Tim, or Gordo:

I'm planning a sport muffler mod soon on a stainless 911 muffler. Which alloy wire should I use with a MIG for welding? Thanks.

Scott

[stownsen914]

Originally Posted by stownsen914

Quiet Boom, Tim, or Gordo:

I'm planning a sport muffler mod soon on a stainless 911 muffler. Which alloy wire should I use with a MIG for welding? Thanks.

Scott

Anyone know? Thanks in advance.

Scott

[MrPerkles]

Originally Posted by JMatta

Yes...I have a Dansk 2 in 2 out that I'd love to know what's inside. My car is already quite loud, as I'm running headers on it (2.4 ltr).

[berettafan]

it would seem part of the purpose of the various routings inside these mufflers is to equalize backpressure for both sides. yes? no?

[911pcars]

What does the inside of a 2in/2out Dansk look like? Anyone?

Sherwood

[Gordo2]

For M Scahfer: nice work, are you adding a second tailpipe as well or just gutting to get a litte more sound? Either way, for the cost of a used muffler, it's fun to play with. I probably went a little overboard in how I went about mine.

Scott: I went with whatever Lincoln wire they have at Home Depot/Lowe's - I think I went with a small diameter wire - like .025 or something.

Gordo

[stownsen914]

Originally Posted by berettafan

it would seem part of the purpose of the various routings inside these mufflers is to equalize backpressure for both sides. yes? no?

Also less back pressure in general (for both sides).


Gordo: thanks for the information.

Scott

[911 tweaks]

any updates form those who did any mods to a muffler as to how their version worked out...??
thx, bob

[M Scahfer]

It's been almost six years since I sawed into my muffler after gordo's post that showed me best what and where to cut. Sounds great and with the by-pass pipe engine breaths better. The guy who welded it up said it was tricky, two thin layers of the shell make it harder. Plus the weight savings is nice. My version is a one in and one out muffler still.