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 6Likes
09-22-2016, 04:27 AM
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CC Member
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Join Date: Jun 2014
Location: Perth,
W.A
Cobra Make, Engine:
Posts: 52
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Glass pack sidepipes
Running live side pipes and keeping the noise level within the regulations is a challenge. I am thinking of using two 2.5'' 24'' glass pack mufflers ( hot dogs etc) Engine is a stock 430 hp LS3 with factory VE catalytic converters. Anyone tried this type of set up before? I need to keep the outside diameter of the mufflers under 4'' due to space limitations. Appreciate any feedback or ideas.  |
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09-22-2016, 08:24 AM
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CC Member
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Join Date: Jan 2002
Location: Melbourne, Australia,
VIC
Cobra Make, Engine: AP Pace427 (AP4033) GM L77 6.0L TR6060
Posts: 838
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The VE cats make a big difference, so that's a start. On my undercar system I had VF cat, one muffler (straight through) two baffle plates and three steel wool balls on each side and the system is 2.5" stainless pipes. That kept it under 90db each side as required.
Sorry, I know that's not exactly helpful for your sidepipes, but the baffle plates and wool balls might help. Are you after temporary of permanent notice reduction?
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Guy
Cobra Progress guye-cobra.blogspot.com
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09-22-2016, 07:07 PM
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Join Date: Apr 2006
Location: Mildura,
vic
Cobra Make, Engine: FFR Coupe, 416ci of LS goodness
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Glass pack mufflers are not known for being quiet.
If you are serious about muffling down your side pipes you might want to look into building them with a spiral or baffle arrangement.
I ran 2.5" perforated pipe packed with stainless wool and then wrapped with weld blanket.
They weren't the quietest but they were easy to live with.
The weld blanket made the surface temp of the pipes lower too.
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09-22-2016, 07:33 PM
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CC Member
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Join Date: Apr 2010
Location: melbourne,
vic
Cobra Make, Engine: Robnell Blown LS1
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Quote:
Originally Posted by guye
The VE cats make a big difference, so that's a start. On my undercar system I had VF cat, one muffler (straight through) two baffle plates and three steel wool balls on each side and the system is 2.5" stainless pipes. That kept it under 90db each side as required.
Sorry, I know that's not exactly helpful for your sidepipes, but the baffle plates and wool balls might help. Are you after temporary of permanent notice reduction?
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And be careful not to overheat your 'wool balls' 
That would be bad !! |
09-22-2016, 07:37 PM
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Join Date: Apr 2010
Location: melbourne,
vic
Cobra Make, Engine: Robnell Blown LS1
Posts: 296
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I found the easiest way to lower the db from my sidepipes is put in earplugs!! 
Join the revolution I say.. |
09-22-2016, 09:57 PM
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Join Date: Jun 2014
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Anyone using the spiral inserts? I have heard good things about them. The noise level is to pass the noise police test.
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09-22-2016, 10:00 PM
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Join Date: Dec 2015
Location: Perth, Australia,
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What type of cobra is it? Just interested as I'm in Perth too.
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09-22-2016, 10:05 PM
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Join Date: Jul 2012
Location: Melbourne,
Vic
Cobra Make, Engine: Pace 427SC. LSA Supercharged with 6sp TR-6060 trans.
Posts: 463
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Quote:
Originally Posted by Cobrakiller
Anyone using the spiral inserts? I have heard good things about them. The noise level is to pass the noise police test.
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I believe Bernie (BMK) runs them in his sidepipes on his Kirkham. From what I understand, he left them in even after getting the car on the road.
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www.paintwerks.com.au
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09-22-2016, 10:22 PM
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Join Date: Apr 2010
Location: melbourne,
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Cobra Make, Engine: Robnell Blown LS1
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A possible solution:
You already have the cats fitted which drops the noise level some.
Fit the spiral wound internals with supertrapp ends.
Would be compact and adjustable.
How is the noise test done in W.A and what level do you need to achieve?
I used the magnaflow glass packs on my sidepipes which were ok when cruising but when you stepped into it then it would bark !!
We have to meet the noise level at a specific RPM which is where the ability to tune comes in.
Then you come across the performance/noise issue as well.
Cam changes etc will change the noise characteristics also.
Last edited by kyleb; 09-22-2016 at 10:35 PM..
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09-23-2016, 12:44 AM
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Senior Club Cobra Member
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Join Date: Feb 2006
Location: Melbourne,
VIC
Cobra Make, Engine: RMC, carb 347 TopLoader and Jag running gear ~ so old school I time it with an hour-glass :D
Posts: 1,293
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Quote:
Originally Posted by Cobrakiller
Anyone using the spiral inserts? I have heard good things about them. The noise level is to pass the noise police test.
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I am running auger style inserts inside my sidepipes
The casings were custom made and the auger sits inside a perforated steel tube which is the inner for the main body of the side pipe.
Overall a 4" OD IIRC
They took a lot of bark out of the exhaust
I have followed my car from behind and cant really hear the exhaust
I have left them in for the last couple of track outings
LB |
09-24-2016, 07:05 AM
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CC Member
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Join Date: Aug 2000
Location: Australia Geelong,
VIC
Cobra Make, Engine: Real: Southern Roadcraft, SRV8, 351W stroker
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glasspack sidepipes
I have glasspack sidepipes. And they arn't excessivly loud. I include a thumb sketch of their construction. I couldn't get pic to load so look at page 5 in my gallery.
Cheers,
Bryan
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If it doesn't matter what gear your in you have enough torque.
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09-24-2016, 04:34 PM
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Join Date: Nov 2009
Location: Cheltenham,
Vic
Cobra Make, Engine: Classic Revival CR3516, LS3, Aussie Mike'd T-56, 3.70 LSD, AP brakes, Penske shocks
Posts: 1,616
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Mine are a 4" tube, 2.5" perforated inner which then has pot scourer donuts stretched over it. Sorry dont have a pic of the scourer setup to hand. Dont use steel "wool" as it can burn, whereas the scourers are more like wire mesh. I got the scourers from Woolworths, 3 to a pack were about $0.60 I think, needed less than I thought I would. Anyway with all this my system is pretty quiet but I think the cats do more than the pipes....
Modena's progress update
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Ben in AU
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09-24-2016, 04:52 PM
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Join Date: Jan 2002
Location: Melbourne, Australia,
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Cobra Make, Engine: AP Pace427 (AP4033) GM L77 6.0L TR6060
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Yes. To be clear, we used steel scourers not wool (as Ben says). And in the undercar setup I inserted them towards the rear, further away from the hot engine end as possible (as Kyle says). I get that this isn't so easy in sidepipes!
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Guy
Cobra Progress guye-cobra.blogspot.com
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09-27-2016, 09:50 PM
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I am thinking of using these side pipe covers, they have a fiberglass insulator on the inside to keep the heat down. ( I have a confession, I don't own a cobra instead I have 63 Corvette coupe but my build is an ICV and this is the only forum that deals with ICV's, a lot of our issues are similar though) Max. pipe o.d. is about 3'' to 4'' depending on how far you space the covers out.
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09-27-2016, 10:16 PM
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Join Date: Apr 2006
Location: Mildura,
vic
Cobra Make, Engine: FFR Coupe, 416ci of LS goodness
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What ever you do, don't try to be different and put a Windsor in it!
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09-28-2016, 01:31 AM
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Join Date: Jun 2001
Location: munno para west,
sa
Cobra Make, Engine: absolute pace chassis #50 L98 & 6 speed auto
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Quote:
Originally Posted by Gav
What ever you do, don't try to be different and put a Windsor in it!
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why would he want to go slower for lol i like those covers not seen those before
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10-09-2016, 02:51 AM
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Join Date: Feb 2009
Location: Geelong,
Vic
Cobra Make, Engine: DRB, 302 EFI 5 speed 9"
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I had 2 cats and 4 mufflers on a under car system with a stock engine and was still 1db over in Victoria.
It was quite than a BF GT
Good luck getting it quiet
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Ross
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10-09-2016, 04:30 AM
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Join Date: Jun 2012
Location: Naracoorte,
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Cobra Make, Engine: CR Cobra 3169
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I have a fg cat on either side with a 1.2 metre hotdog with perforation, and I just had my first inspection. They produced about 100 db, then I stuffed 5 scourer into the end and it brought it down to 95 db. So Now I am looking for a very small diameter muffler to quieten it down to a legal level.
302 windsor. The engineer went through a lot of jargon about frequencies etc and tuning the exhaust to counteract them. We played with the idea of inserting to tin can into the end with a stiff wire and sliding the can inside the hotdogs whilst it is running until you hit the sweet spot . The test is done running the engine in neutral at 3300 rpm.
JD
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10-09-2016, 05:49 AM
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Join Date: Dec 2015
Location: Perth, Australia,
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Quote:
Originally Posted by guye
Yes. To be clear, we used steel scourers not wool (as Ben says). And in the undercar setup I inserted them towards the rear, further away from the hot engine end as possible (as Kyle says). I get that this isn't so easy in sidepipes!
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Just so I understand... Are we talking about these sorts of things?
https://www.woolworths.com.au/Shop/B...roductId=10924
Or perhaps these?
https://www.woolworths.com.au/Shop/B...productId=2774
I never would have thought of stuffing such a thing in there! It really works huh? |
10-09-2016, 05:51 AM
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Join Date: Nov 2009
Location: Cheltenham,
Vic
Cobra Make, Engine: Classic Revival CR3516, LS3, Aussie Mike'd T-56, 3.70 LSD, AP brakes, Penske shocks
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yes these are what I used
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Ben in AU
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