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-   Tech Tips (http://www.clubcobra.com/forums/tech-tips/)
-   -   Muffler replacement huge horsepower gains! (http://www.clubcobra.com/forums/tech-tips/95927-muffler-replacement-huge-horsepower-gains.html)

RedBarchetta 04-19-2009 12:02 PM
Quote:
Originally Posted by undy (Post 941466)
Eric, The flutter occurs when the mufflers are installed as they are intended, for max sound attenuation. When I installed the inserts before, with the louvers being ineffective for max flow and minimal sound attenuation, there was no flutter. This flutter issue is very wide spread, not just your systems (no pot shotz at CC intended here at all, I've always been happy with your stuff and customer support).

You have any thoughts on this flutter issue??

Dave
Hi Dave. Just a note on the Stainless Specialities mufflers. They do not have a directional louver within them. It's a stainless steel mesh that holds back a ceramic blanket material. I would also suspect that the blanket material gets coated over a duration, as my pipes are louder today than they were when new. WOT will alert every police officer within a 1/2 mile radius (maybe up to a mile if they are down wind.). Ear plugs are mandatory and I have just gotten used to using them all the time now. They also cut down on the wind noise when doing 70-75 on the interstate.

-Dean

Rare Iron 04-19-2009 06:39 PM
Quote:
Originally Posted by undy (Post 941466)
Eric, The flutter occurs when the mufflers are installed as they are intended, for max sound attenuation. When I installed the inserts before, with the louvers being ineffective for max flow and minimal sound attenuation, there was no flutter. This flutter issue is very wide spread, not just your systems (no pot shotz at CC intended here at all, I've always been happy with your stuff and customer support).

You have any thoughts on this flutter issue??

Dave
Dave, I'm not really sure what this can be. I would suspect the louvers in the flowpath are creating this, but if someone running mufflers with smooth perf cores are having the same effect, then that would blow my theory out of the water. I've heard of other sounds described on decel & in-between shifts on manual cars - like backrapping, popping, etc. This is not limited to my mufflers. If you listen to the Z06 Corvette on my website, he is running 3" Powersticks x 20" long, & he accelerates from 30 MPH to 140, then takes his foot off the gas for an extended decel. NO popping or fluttering at all, AND he was not even running tailpipes - the exhaust was dumping under the car! I did not expect it to sound that clean. He was also running into the louvers as suggested.

undy 04-20-2009 04:01 AM
Quote:
Originally Posted by Rare Iron (Post 941614)
Dave, I'm not really sure what this can be. I would suspect the louvers in the flowpath are creating this, but if someone running mufflers with smooth perf cores are having the same effect, then that would blow my theory out of the water. I've heard of other sounds described on decel & in-between shifts on manual cars - like backrapping, popping, etc. This is not limited to my mufflers. If you listen to the Z06 Corvette on my website, he is running 3" Powersticks x 20" long, & he accelerates from 30 MPH to 140, then takes his foot off the gas for an extended decel. NO popping or fluttering at all, AND he was not even running tailpipes - the exhaust was dumping under the car! I did not expect it to sound that clean. He was also running into the louvers as suggested.
All things said, I'm am very pleased with the Cobra Packs.. You really have to be listening hard to pickup on the flutter. The more I drive it the less noticable it's becomes. As I said earlier, from outside the cab you can't hear it.

What I really like about the Cobra Packs are ... the rumble at idle is deeper, more mellow and best of all quieter than the Cobra Sticks were. It still screams at WOT though, as it should. The "under the overpass" melodies are very pleasing too..:D .. ya jus' can't resist that throttle blip on entry to let 'em know you've arrived:JEKYLHYDE

DRBB 04-22-2009 01:48 AM
Does this thread apply to all cobra sidepipes? I am curious if anyone knows about Unique Motorcars side pipes?

mickmate 04-22-2009 06:05 AM
Sure it does, are Unique slip fit or flange? They will both be covered here.

mickmate 05-11-2009 09:17 PM
Looks like another Classic Chambered fan
http://www.clubcobra.com/forums/show...threadid=96873
I'm ordering another set tomorrow. Two of these cars are close to running.

mickmate 06-29-2009 12:32 PM
Good news to report, two of the three recently installed sets of Classic Chambered have been fired up. Funnily enough it was literally within minutes of each other. They sound pretty good even running indoors with both sets. I got the opportunity to log on a few miles with a set of the 2.5" using the transisition cones both on entry and exit to the mufflers. I ran my kids around in the car and found them quite easy to hear and talk to while driving. I received several comments about how loud they were from outside the car, some were car guys that said awesome, others were whiny neighbours that question the legality of such noisy exhausts so take that for what it's worth. No need for earplugs and plenty of power though I can't comment on the before and after difference in power from them. The customer will probably weigh in on it.

DocDirk 06-29-2009 03:42 PM
HP Gains
 
I had my 533 BB Ford chassis dyno'd before and after changing from stock 1 7/8" ID baffles to 2 1/2" ID baffles and the result was a gain of almost 50 peak RWHP, and increased low end torque. I'll post the dyno graphs when I have them...should be today or tomorrow.

Regards!

Dirk

Dwight 06-29-2009 04:26 PM
Classic Cobra mufflers
 
I changed my mufflers last winter from 2 1/2" x 24" Lone Star mufflers to 3" x 28" COBRAPACK MUFFLER. My 302/354 dyno'ed at 402 rwhp 416 rwtq. I do not know how much I gained with the new muffler because I changed heads, cam, intake, TB, mass air, etc.
But I love the sound, loud but not to loud. I can cruise at 70 and talk to the passenger. I could not do that with to old mufflers. Nice deep rumble.

I highly recommend the Classic Cobrapack mufflers.

www.classicchambered.com/

Dwight

Dwight 06-29-2009 04:49 PM
DRBB

About 4 or 5 years ago I removed the fiberglass packing from a friend's Unique side pipes. He bought the kit in early 90's maybe 91 or 92. The pictures tell the story better than I can.
Another friend, Mike had his Unique side pipes replaced with the Classic Cobrapack last fall and love the power (seat of pants) and sound.
Dwight

http://www.clubcobra.com/photopost/d...epipes_6_1.JPG

http://www.clubcobra.com/photopost/d...depipes_4_.JPG

KarlCSX2498 06-29-2009 06:40 PM
New classic chambered mufflers
 
Hello, I had Nick replace the mufflers in my side pipes with the CC 2.5" packed mufflers. I just started the car for the first time (it is a brand new car, scratch built) and the pipes sound fantastic. Not loud but a low rumbling sound and the idle sound is perfect. If I can get a few details complete, I should have a test drive this weekend. I hope to have a video on the club cobra site in the next couple days so everyone can hear.
Nick did a great job and I highly recommend his services.
regards, karl


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