taming loud exhaust

[dw1]

I've got a Fabspeed Euro premufler in place of the original cat., and a Dansk 1-in-2-out on my '87 3.2.

While I like the sound, at highway speeds and when I get high in the rev range, it is just plain too loud. I also think I may be giving up some mid-range HP in favor of high-end performance with 2 large open pipes.

I've thought about a cap on one side, but I think it would be interesting to put in an electric exhaust cut-out valve to close off one side except when I want it open.

Has anyone seen an exhaust cutout valve that needs only a bare minimum of straight pipe, or is suitable for putting onto a curved pipe?

I ask because the outlet pipes from the muffler are a sort of S-curve with no real straight section.

I'm also open to alternate suggestions (baffles?), but I would like to keep this muffler.

[ivangene]

after reading your bumper mod post I was going to ask how you like the muffler....guess this answers that

[dw1]

I do like the muffler, but above 3200 rpm or so I'm just a bit paranoid about attracting the attention of those who protect and serve if I'm unable to restrain my right foot in a quiet neighborhood.

If I plug one side, the sound level drops by 10 - 12 dB. Interestingly, plugging the passenger-side pipe had a larger effect.

I do fondly remember an informal "show me what you've got" run with my car and a 427 Cobra repro on a local franchise freeway. The sound from both of our cars was great.

[rattlsnak]

I have a similiar issue. I have a straight cat by pass with a B&B 1 in /2 out and man is it ever loud. it truly sounds like a big block with open headers..! I'm looking to either add a premuffler, or getting one made from a magnaflow or something. How much will installing a premuffler quiet it down?

[dw1]

rattlsnak,

The premuffler is quieter than a straight -tube cat bypass, but I didn't measure by how much. My "seat of the pants" feel is that the difference was not as significant as I had hoped.

[Dublinoh]

I capped one side of a m & k and it helped a lot....funny worked best on drivers side. Electric valves I have seen were pretty large...

[rattlsnak]

thats what i figured... Did you have a straight tube first as well and then added the premuffler?

[Jaskas]

I have an elektric cut out on my 2-out system. It reduces the noice nicely when needed.



Installed:




Offcourse it cuts dow on the power a bit, but when just cruising it doesnt bother me that much. And with flick of the switch you have the full roar available

[dw1]

Jakas,
That is what I am looking to do! I figured someone in this creative group had done it.

It is, unfortunately, kind of hard to tell the mounting and dimensional details from the photos. Do you have a sketch or drawing with some basic dimensions available? I'm thinking that you made some measurements to get the pipe cut & welded.

What type of muffler did you start with, and what size valve are you using? My pipe appears to fall between the valves made for 3 and 3.5 inch pipe.

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Rattlsnak,
Yes, I did try the straight pipe - a "test pipe" it was called - and it was maybe a bit louder with that than with the Fabspeed premuffler. More importantly, changing from the pipe to the premuffler changed the tone by making it a bit less "tinny" and it seemed to eliminated a resonance.

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Dublinoh,
Yeah, I thought of a cap, and that is probably what I'll do if I can't make anything else work out, but I like the idea of flipping a switch to open up the closed pipe.

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Thank you all for your inputs.

[Jaskas]

I have quite simple exhaust. Its basically 993 headers + 993 cat + 2x2,5" 90 degree SS angles


I used 2,5" valve from raceready performance. Allready broke one last summer, and the warranty did not cover for is.

I didn´t do any exact measurements. I just put the two flanges on the pipe to find the best spot for the valve. ( The fit is really thight as you see in the pics) Then i spot welded the flanges on the pipe, cut it and tested the fitment. When the fitment was ok, it was time for final welding.

[Steve 82SC]

Ben. of M&K muffler fame, used to have a short, perforated stainless steel sleeve that fits into either side of the exhaust tailpipe. This is not a cap, but rather a sleeve that changes tone and DBs just enough to possibly take care of the problem. It requires a small hole being drilled on the underside of the tailpipe and is secured with a sheet-metal screw, easily removable quickly and without getting dirty. I had a complaint similar to yours on my old system. It doesn't make it whisper-quiet by any stretch of the imagination, but it takes that "edge" off at higher rpms. You can use a sleeve on one side or both, depending on your tastes. Give him a call......it may be the answer to your issue. And, it's sure less complicated than an electric cut-out.

Steve

[rattlsnak]

Those are probably C&C inserts. They are used commonly with the 993 crowd on fab speed super cup exhausts. I had them also. They did work well. They would have to mount in the test pipe or premuffler though if you have short exit pipes.