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Join Date: Aug 2004
Location: Stuck in NJ
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3.2ish free flow exhuast

This is just for 's and giggles'. I'll have to post a sound clip when it gets warmer.

1987 Cab, 3.5 LN jugs, 9.5:1 JE pistons, twin plugged, 8-10 psi supercharged, and other stuff. Had a set of Dansk SSI's used just for winter heat. Never mind the primary is too restrictive, the secondary is 2" which just makes things worse, and it was running into a Dansk 2 in 2 out .

So, cut off the secondaries, weld on 2.5" and run that through independent 21" 2.5" glass packs, one for each bank. All just an exercise in welding. In case you wondered how loud? Could have just run open headers and it would be the same ding. Now shopping Amazon for deal on Noise Cancelling Headphones. But, it does rev up quicker, lol.




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Kuehl
1987 911 cab, modified
https://griffiths.com/
Old 01-10-2020, 01:41 PM
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Pretty slick.

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Old 01-10-2020, 02:47 PM
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Nice Charlie. I can hear it from my house... sounds good.
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Karl ~~~

Current: '80 Silver Targa w /'85 3.2
Prior: '77 Copper 924. '73 Black 914. '74 White Carrera. '79 Silver/Black/Anthracite 930s.
Old 01-11-2020, 01:44 AM
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If you want it to be a little quieter try extending the tailpipes a couple of inches past the bumper.
Old 01-11-2020, 06:57 AM
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Got a chance to record a quick sound clip in the shop before I started working on plan B.

So the objective was to have heat and better flow.
The best flow with the SSI's choking everything was the 2.5" secondaries after the merge to separate "mufflers". The 'mufflers' we tried were simply straight through
2.5" ID glass packs approximately 18" long. This is 1 step above open headers.
I can say, and no dyno needed, she did rev quickly (even though our ign advance is conservative), and she did pull like a crazy lady at top end. But... you cannot stand near the car never mind drive it with this test exhaust system.

Exhaust Video
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Kuehl
1987 911 cab, modified
https://griffiths.com/
Old 02-08-2020, 08:25 AM
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The video is set to private.
Old 02-08-2020, 08:33 AM
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I just changed the publish date from tomorrow to today.
try it again
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Kuehl
1987 911 cab, modified
https://griffiths.com/
Old 02-08-2020, 09:08 AM
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That’s a sound I’d love to hear fly-by, but hate/hate to live with. Is it still in this configuration?
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Ken
1986 930, 1969 Mach1, 2003 540 Sport, 2016 R1200RS
Old 05-16-2020, 07:40 AM
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When I turn the volume up or down, it gets louder or softer. A reference dB number would communicate better - a suggestion for all “sound” threads.

But I get the idea. Bigger muffler(s).

Sherwood
Old 05-16-2020, 08:25 AM
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Yeah, db ratings would be interesting but you would need to develop standards.

So, I took the complete glass back system off, simply too loud no matter if the power gain is worth it. Its for sale if you want buy.
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Kuehl
1987 911 cab, modified
https://griffiths.com/
Old 05-16-2020, 01:56 PM
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So, my objective was to have a free-flowing system, not particularly tuned to a given rpm or load; could do that another day. Anyway, a free-flowing system using 2.5" immediately after the collector and into the muffler that is not too loud and does not kill power.

So I cut off the narrow inlets on my Dansk 2 in 2 out. And, I noticed Dansk uses 2.5" through the insides between the baffles! What a piece of luck! Opened up the exterior can, welded in 2.5" and routed that back to the V bands at the collector. Now I can use my SSI' heater boxes in the winter and run my 1.75" RSR headers with the same muffler in the summer.

I'm used to the sound of the Dansk 2x2, and in terms of power, it does not really take that much off.

Took it out for a 3 hour joy ride on the back roads and a piece of highway. This is the perfect set up for me.

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1987 911 cab, modified
https://griffiths.com/
Old 05-16-2020, 02:05 PM
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Looks nice

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Old 05-16-2020, 05:24 PM
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Quote:
Originally Posted by kuehl View Post
Yeah, db ratings would be interesting but you would need to develop standards.

So, I took the complete glass back system off, simply too loud no matter if the power gain is worth it. Its for sale if you want buy.
A decibal is a standard reference for measuring sound pressure levels.

While most not lab certified, there are several cell phone dB apps. Some are more accurate than others. There's no other way to communicate loudness level unless everyone had a standard fixed volume setting on their playback device.

If you measured the dB level from a repeatable distance and height and recorded a video, viewers could adjust the video audio playback level on their cell app to the same level and get a more accurate idea.



I measured a live 110dB rating of an equiv. RSR at the LB Gran Prix couple years ago (it hurts). When someone plays it back on their device, it can sound like a Singer sewing machine or a Space Shuttle at take off - via their volume control.

Sherwood
Old 05-16-2020, 05:50 PM
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If you measured the dB level from a repeatable distance and height and recorded a video, viewers could adjust the video audio playback level on their cell app to the same level and get a more accurate idea. Sherwood

Yup, and none in tunnels, against walls, etc

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1987 911 cab, modified
https://griffiths.com/
Old 05-16-2020, 06:36 PM
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