Exhaust Question - Need advice

[KR4MC Steve]

I installed a resonator tip by 3A Racing with 2 1/2 id.
Clamped it to the hacksawed off stub of the non-resonated chrome tip the muffler shop welded to my Dynomax Super Turbo Muffler.

The Roar at 3000-3200 is still there just the same.

The overall sound got a little deeper & more mellow, but the volumne & growl on acceleration seems to be the same.

The overall length of the tip remains the same ( 8" plus a 1" stub to clamp to versus 9".

I did this before I found the enginnering exhaust info on the net.

Hope this helps.

[Lars1776]

What is interesting bout all this is that one can revise his/her stock system using only ONE muffler and have the resonance problem. Didnt even need to be a glasspac!!!!!!
The lackof drone with the stock system is based on proper DESIGN of the system, while we are doing the typical backyard hot rod 'try it and lets hope its OK' concept, and now you have to use its corollary of 'If it dont work we will change it until it does'!!
Those that bought an aftermarket system 'should not' have a problem if the manufacturer stated ' a little louder than stock'.
But no consolation to those that are doing it piecemeal, think our friend in the NL is experiencing this tothe max!
He had a hint in his last post, cant get to it while typing this.
Someone else also found extending the exhaust typ an inch or so beyond the end of the rear pan helped. And others suggested extra insulation.
IMHO all of the above may be necessary- this be a cut and try mode not a This WILL Work mode.
Now
I gots a Subaru Legacy GT wagon, and had the sad occasion to take a 40 mile highway trip as back seat passenger. LOTS ofnoise and could hardly hear front seat passengers! Decided to check the extent of sound deadening, pulled off the rear cargo side panels and carpet, and LO- almost nihl>
So off to me favorite auto upholdstery shop and goe me some dense grey recycled 1/2 inch thick padding he uses in street rods and customs. (No not that aluminum faced thin stuff...).
$15 worth of this, some 3M Super WS adhesive, and 3 hours of work and the Roo no longer sounds like I am sitting in the bed of an ole pickup driving at 50 mph.
He's trying to say it will take some time and effort to solve this turkey of a problem.
ONCE one of the list gets his right, hope he will post it will ALL the details in cluding muffler make model location tailpipe extension, etc etc.
Then the list can build a library of solutions......
Go for it!

[Comedy Cruiser]

....maybe I'll just go back to the stock muffler and when I drive I'll make loud grumbling sounds...

[theo]

I could be wrong but when i make the more quiet baffles longer with an extra piece of metal atached to them (and the extra metal more narrow). And put some absortion materials around the baffles. It will be probely more quit. If this doesn't help i will put a extra metal pipe to the baffles but then with holes in it so the absortion metal will do his work better.

Another option is a extra muffler but first want to try it without many extra work, i have to say that by just narrow the inlet of the baffles the sound is already more quit end low end torque comes back a little, so i have good hope that the thing i just explained is going to work.

I could have some advice on with absortion material i should use any info is welcome.

Theo

[Sci-Fi]

Originally posted by theo
I could have some advice on with absortion material i should use any info is welcome.

Theo

You can probably go to your local motorcycle shop and buy some silencer packing from them. Here's a link with prices to give you an idea of the costs:
http://www.rageperformance.com/silencerpacking.asp

The other alternative is to replace the long single centerline muffler with a muffler and a resonator to control the sound or drone. Adding heat shielding material in the centerline tunnel will also absorb noise from entering the cabin. An old trick is to buy a muffler or glasspack with the inner tubing that is larger than the entry or exit diameter of the exhaust tubing to allow the exhaust gas to linger longer in the muffler to absorb the sound. Acts like an expansion chamber. Hooker used to make a muffler that had a chamber that was larger than the inlet and tapered to match the exhaust pipe diameter to control noise or drone.

[PTGT Redman]

pt chruzin,

It's the dual outlet single tip

[Grouch]

Just buy a Bassani. You get the nice mellow sound
( No burbles though ) also no droning at any speed If you want it loud you take an allen wrench and a tool with a hook and remove the baffle I made a tool out of an old Phillips screwdriver. It take less than 5 minutes to do it If the engine is cold.If it's been running for a while forget it.

[Lars1776]

Sci FI definately has some hints, esp since these devices are used on motorcycles quite a bit. Your comments on the changing of torque is also very interesting.
In the 'Old Days' when folks added dual exhaust to their cars they thought they would get better performance AND more MPG.
What happend was more performance but with the increased flow of exhaust thru the system, they also had more unburned gas passing thru the system, hence lower mpg.
Could be with todays fuel injection and computers that does not happen, but since you report the low end torque changing, maybe it does.
Any rocket scientests on board???

I am sure your experience will help others so continue your interesting posts Theo!

[Lars1776]

more info to confuse...
.
http://www.norcal-saac.org/ot/sound_table.htm

This URL takes you to a sports car competition car/info chart showing various cars withengine mods, etc.
A little work will take you down to a VIPER ofall things, using
supertrapp units but of huge 4" diameter pipes, and look at
the low DB.
Much more info too....even some Dynomax mufflers. The Lobak
is an perforated megaphone but available for only 3" and up diameters. See http://www.secureperformanceorder.co...ProductID=4733
All FYI or FYConfusion..

[theo]

Originally posted by Sci-Fi

The other alternative is to replace the long single centerline muffler with a muffler and a resonator to control the sound or drone. Adding heat shielding material in the centerline tunnel will also absorb noise from entering the cabin. An old trick is to buy a muffler or glasspack with the inner tubing that is larger than the entry or exit diameter of the exhaust tubing to allow the exhaust gas to linger longer in the muffler to absorb the sound. Acts like an expansion chamber. Hooker used to make a muffler that had a chamber that was larger than the inlet and tapered to match the exhaust pipe diameter to control noise or drone.

Thanks for the info Sci-Fi!

I think that what i have done by making the inlet of the baffle more narrow has the same idea. Closing the outlet of the system a little more makes the exhaust gas stay longer in the resonator (and piping).
When ordering this system i didn't realize that it was this loud never heard any european car with this kind of noise outside ore inside the car! Even when they have added a sport muffler.
The thing what i liked about it (and still do) is the looks and the spare tire that still is under the car.

About the back pressure;
When the exhaust system just have been installed i drove away and the engine turned of, i drove away like i was used to do before it was installed just let the clutch come on slowly without giving any gas. Before i narrowed the baffles i have to give gas when driving away normal, otherwise the engine would shut down. Now i almost can drive away again like i used to. So back pressure is coming back again not like it was when i had the sock exhaust on it. So probely it's save to close it down a little more will try it this weekend if the weather is good enough. But i'm gonna use the extra baffles i received for the example i'm giving earlier in this thread. First i have to go by a partshop because i want to use the T-304 steel for the extra piece of metal i want to atache to it. When a have good results i will let y'all know. I really like the feedback from you all when i have any quistions just want to let you know that

I'm not sure what you mean with glasspack i have read this a few times already i presume it's a kind of absortion material.

Theo