Muffler replacement huge horsepower gains!

[mickmate]

Rodknock I hadn't planned on testing the Hushpowers/Flowmasters but I can help you with installing or testing them or maybe someone here has tried them already. Good to know there's another source. One of the goals of this thread is to draw out more options available to us.

[RodKnock]

Originally Posted by mickmate

Rodknock I hadn't planned on testing the Hushpowers/Flowmasters but I can help you with installing or testing them or maybe someone here has tried them already. Good to know there's another source. One of the goals of this thread is to draw out more options available to us.

I actually have them installed on my car. They advertise Hushpower's in the Vintage Motorsports magazine as being less restrictive, but quieter, in order to pass sound at the various tracks around the country. I'm curious if they're any better than the alternatives out there.

[dont]

I changed out my stock 2.5" ID mufflers to 3" ID Cobra packs and picked up 16 HP and TQ on a chassy dyno. For the transition I expanded the 3" tails that come out of the Cobra packs to a tight slip fit into my existing 3.5" pipes. I have the fluttering when I push in the clutch coming to a stop. There are pics in my gallery of the process.

[undy]

Originally Posted by dont

I changed out my stock 2.5" ID mufflers to 3" ID Cobra packs and picked up 16 HP and TQ on a chassy dyno. For the transition I expanded the 3" tails that come out of the Cobra packs to a tight slip fit into my existing 3.5" pipes. I have the fluttering when I push in the clutch coming to a stop. There are pics in my gallery of the process.

I too have a similar fluttering noise with my new 3" Cobra Packs.

[madd matty]

i am replacing the muffs on a superformance two grand if done well . first 10 to 15 hp. lost at the colector; it must be blended with grinder and re tigged. second back presure is bull. if you have a heat sensor gun point it at your side pipes at the point of the biggest heat drop thats it you could cut your pipe off and it would be perf. i have done this on drag cars and it is all good . but this is just my opinion ie new member.

[cdnus]

Dean
If you look closley at mickmate's photo you will see that rather than the end washer/baffle being welded directly to the perforated core there is now a solid sleeve welded to it. Now the perforated core fits over the sleeve on both ends allowing it to float when it expands and contracts. That's what was the problem with the old version, you would get cracks at the welds on the perforated core & all the packing would get sucked out.
Now with the two pieces not welded together the core can expand all it wants and will not crack or split.

Craig

[BMEP]

Great thread! I'd love to hear more about the flutter. When exactly does it happen? Seems like it's heard any time the engine is losing revs - is that right? Is it a constant sort of slapping/flapping sound or is it more of a random popping?

I've read every muffler thread I can find because I'm about to build a set of sidepipes for my FFR. I want minimal power loss and noise is okay as long as it's not crazy. I'd been planning on the same sort of setup (except with merge collectors) that RedBarchetta has but now I'm wondering if that's the right thing to do...

Rob

[dont]

Mine only makes the fluttering noise during the time when the clutch is depressed until it reaches idle RPM's. If I leave it in gear during slow down it sounds fine. To me it almost sounds like the motor is inhaling instead of exhaling.

[cdnus]

It would be interesting to find out if this "flutter" is associated to engine displacement & muffler size. Do the members with big displacements encounter this noise (427+) ?
Is it only smaller (408-) that encounter it?
When I had the original VERY restrictive mufflers I did not have any "flutter" but as soon as I installed the S/S 2.5" mufflers I started getting it.
It's almost as if the flow capacity of the muffler is too much for the engine @ lower RPMS & you get a "sucking effect" that causes the fluttering.
I suspect that if I installed 2.5" turnouts the problem would go away--would look rediculous but might solve the problem. (not going to happen)

Not being a engineer & not knowing anything about expansion-contraction-heating-cooling-velocity of exhaust gasses this is my best shot at the problem.

I am sure that someone here is & can answer with a more accurate solution/cause/effect.

Craig

[undy]

Originally Posted by cdnus

It would be interesting to find out if this "flutter" is associated to engine displacement & muffler size. Do the members with big displacements encounter this noise (427+) ?
Is it only smaller (408-) that encounter it?
When I had the original VERY restrictive mufflers I did not have any "flutter" but as soon as I installed the S/S 2.5" mufflers I started getting it.
It's almost as if the flow capacity of the muffler is too much for the engine @ lower RPMS & you get a "sucking effect" that causes the fluttering.
I suspect that if I installed 2.5" turnouts the problem would go away--would look rediculous but might solve the problem. (not going to happen)

Not being a engineer & not knowing anything about expansion-contraction-heating-cooling-velocity of exhaust gasses this is my best shot at the problem.

I am sure that someone here is & can answer with a more accurate solution/cause/effect.

Craig

I have it now with a 600hp 482" s/o and 3" Classic Chambered exhaust.. I didn't have it before with the other 3" CC exhaust. The other set flowed as much as this set.. I'm not really complaining as I've grown used to it and others outside the car don't seem to hear it.

[Dwight]

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]

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

[madd matty]

and we have a winner . i think dean nailed it at least in my case. at 9000miles my left pipe started to buzzzzz . baffle broke weld. It only made noise when hot.

[priobe]

I am currently getting ready to make my mufflers. I dont not want to get the same "flutter sound that everyone is speaking of.

Here is my setup.

My collector is 3.5 and my muffler are 3 in with a 4 inch body. I had a muffler shop expand the 3 inch to 3.5 I.D. I will then cut down the expanded 3.5 ID where the cone shape enters the muffler.

Will I experience this flutter noise?

[priobe]

Originally Posted by priobe

I am currently getting ready to make my mufflers. I dont not want to get the same "flutter sound that everyone is speaking of.

Here is my setup.

My collector is 3.5 and my muffler are 3 in with a 4 inch body. I had a muffler shop expand the 3 inch to 3.5 I.D. I will then cut down the expanded 3.5 ID where the cone shape enters the muffler.

Will I experience this flutter noise?

So it sounds to me as if nobody really knows what cause the flutter.

However, if I install the pipes and described with minimum noise reduction (louvers facing outward I should not receive any flutter?

[undy]

that would be a good question.. Maybe Eric w/ Classic Chambered could weigh in on this flutter stuff???

BTW... my CC inserts without the packing and the louvers facing for minimal noise reduction were unbearably loud, hence the new Cobra Packs installed for maximum noise reduction. I'm very pleased with the sound and performance now.. I'm getting used to the flutter. I talked to a friend standing away from the car while it was running/fluttering and he said he couldn't hear it from his standpoint. Maybe it's only noticable to the driver??

[RedBarchetta]

Thanks, Craig.

Beer for life to the guy that can eliminate the flutter. LOL

[undy]

Originally Posted by RedBarchetta

Thanks, Craig.

Beer for life to the guy that can eliminate the flutter. LOL

I think it's partially due to the lack of a cross-over or X-pipe. It could be affected my muffler baffle design ... or even installation. My last set of CC's sidepipes I ran were simply 3" ID inserts, which slipped into my straight 4" (lake style) sidepipes. I installed them backwards, with the louver "scoops" not scavenging exhaust into the outer chamber. That resulted in max flow with minimal sound reduction. I also had ZERO "flutter". Fast forward to the new set of CC's Cobra Packs. Same muffler design, but with fiberglass in the outer chamber. I installed these with the louvers scavenging exhaust, resulting in a little flow loss but better sound reduction. Now I have flutter.. Was it the different outer housing, the louvers installed in the scavenging manner (that's what I think) or ... the addition of the fiberglass packing..

The "flutter" quandary marches on...

Dave

[mickmate]

Hey Dean, Eric looked at your sketch and made these up from it. http://www.classicchambered.com/clas...cts.html#cobraKidding, but he has them in stock at the bottom of that page as a reducer. We took and cut out just the transition we needed to match diameters and put it on the end like this . We installed them in Dougs 3" and Karls 2.5". They make a really smooth radiused transition between the diameters so if the flutter is caused by reversion off the corners then this will fix it. Karls car will be running soon so we'll have some real feedback on whether it works. What was that about a lifetime beer supply................????????

[RedBarchetta]

Originally Posted by cdnus

When I had the original (SPF) VERY restrictive mufflers I did not have any "flutter" but as soon as I installed the S/S 2.5" mufflers I started getting it.

Craig

Same here. Someone else mentioned that it sounds like paper flapping in the breeze. Great description for those that have not experienced this. There are a lot of annoying sounds that these cars can make (i.e. wind noise on the freeway is louder than any muffler). But the "flutter" is truly annoying and gets harder to live with the longer you have it. I suppose that exhaust pop from a Weber system is another of those sounds that others just deal with. Perhaps more period correct, too.

Originally Posted by mickmate

Hey Dean, Eric...has (reducers) in stock...We took and cut out just the transition we needed to match diameters and put it on...We installed them in Dougs 3" and Karls 2.5". They make a really smooth radiused transition between the diameters so if the flutter is caused by reversion off the corners then this will fix it. Karls car will be running soon so we'll have some real feedback on whether it works. What was that about a lifetime beer supply................????????

Looking forward to reading the updates. Now I just need to find a beer truck idling next to a 7/11 that I can steal.

-Dean