converting 1 out to 2 out

[KennyG]

I have a stock muffler sitting in my garage an I was thinking about converting it to 2 out.
Can this be done out of the car and then install and cut valance to match? Or should the valance be cut and then fit the pipe to it?

Thanks,
Kenny

It's nice to have options.

[Wil Ferch]

This is a classic chicken-or-egg question. I would try to fit the pipe first, because things don't always go well ( in terms of symmetry..at least it didn't for me)...then cut the valence to match.
Hint..for a pro looking job, cut the right side hole with a 45 degree rear-and-up slant on the forward edge...to mimic the left side that has such a slope as part of the rear rocker. Also, take a vice grip, padded perhaps, and slowly work your way around the new right-side hole by giving it a "lip". Then dress the tool marks by sanding or using a rubberized Cratex bit, and have the valence painted. Now it looks "factory".
--Wil Ferch

[BGCarrera32]

I've was contemplating this too a while back. I haven't gotten to the exhaust yet because of the screwed up Fabspeed premuffler issue that delayed things for a month, then the snow thawed and it was time to roll.

I took my muffler off, and stopped in at my CarX man. Pretty cool guy actually, we took it in back and he grabbed a piece of scrap stainless exhaust pipe, and tried to mirror the right side output. He used their large mandrel bender, and I have a piece that should do the trick for the right outlet pipe when I get back at it this winter. It is loose enough of and angle where I should be able to adjust and tack in place.

Here's a shot of a dissected muffler I found somewhere else here...


Something to think about anyway...

[Hetmann]

The bigger question is... If anyone has done this, How does it sound?

[jmz]

seems years ago there was an article/schemtics for converting your factory muffler (1974 stlyle) to the Porsche factory type sport muffler. I don't know if I still have it. I had a local fabricator modify my stock exhaust and it was pretty easy and only $125.00 including the new stainless tips. I had mine done like the rs type muffler w/ the exhauast tips exiting from the mid section.

[Danskman]

Just a heads up for you... when you cut and paste a right side tailpipe to a single outlet muffler, you are not getting the full benefit of a true, dual out system. The Dansk dual out mufflers are designed from the start as a dual out system, and have the internal components to match. A new Dansk dual out muffler is definitely not a single out muffler with a second tailpipe attached to the right side. I'm not saying that making your own is not a doable alternative, but just want you let you know all the facts.

[jmz]

Danskman, you are correct. The schematics I was speaking of include instructions for cutting open the muffler and changing the baffles to work as a dual outlet sport muffler.

[ttweed]

Originally posted by jmz
seems years ago there was an article/schemtics for converting your factory muffler (1974 stlyle) to the Porsche factory type sport muffler.

It was in the PCA Upfixing series- copy of article is here
TT

[911pcars]

The following is probably more applicable to early 911s (pre-74) since there is no removeable valence, but instead a rear bumper.

If you weld on the new tip before cutting out the valence, you can't install the muffler for a trial fit. I would cut the opening in the rear bumper first.

Create a template on the driver's side, then transfer a mirror image onto the passenger side for the cutout. Follow the suggestions to replicate the rounded edge. You can also braze on a piece of round stock bent to follow the curve around the opening, then hammer over the sheet metal to form a rounded lip. All this is easier with fiberglass bumpers/valences of course.

Start with a piece of 90º exh. tubing, then cut and grind to center the outlet in the opening and follow the contours of the muffler, and to match the orig. pipe. Tack weld in about 3 places, remove the muffller, then complete the weld. If you want to use larger pipes (2.5"-3"ID), cut off the orig. tail pipe, then repeat the above on both sides.

Not sure how this setup sounds compared with the usual "internal sport muffler modification". Anyone? BTW, you can modulate the desired exhaust sound by gradually enlarging the passenger side opening into the muffler. I don't think the engine cares which side of the muffler passes more exhaust.

Sherwood Lee
http://members.rennlist.org/911pcars

[Wil Ferch]

Sounds great....think Steve McQueen on the opening lap of Lemans !
--Wil Ferch