Muffler replacement huge horsepower gains!

[mickmate]

Wow there's some super feedback and info coming out already. The first car (Doug hold your horsepower) is John's SPF with a pretty rumpy 7 in it. He actually saved Deans post and info for a looong time to source his mufflers. He got them from Stainless Specialties here http://www.stainless-specialties.com/products2a.htm and I believe they were the Perform Master. The pipes we were putting them into were mild steel and they were getting ceramic coated so there's no need for stainless here but the results were unquestionable, read on. The SPF use the flange to flange for a header sidepipe connection. John and others say it's a bear to get at some of the bolts there's a thread on it in the SPF section on CC. With this first set of pipes I lined them up with the edge of the welding table, tacked some washers to the bench that were bolted through the flange so I could accurately relocate the parts relative to each other. Then I measured the length and tip height of the tail pipe or dump tube. Take a minute to know for sure that you can get back to where you were. There's better methods coming so hang tight. At this point we unbolted it from its makeshift fixture and ceremoniously cut the old muffler out with a chop saw. It worked out really well having the new muffler 1" longer. That gave us a nice clean cut and piece of tube to work with instead of cutting right on a weld and trying to clean that up without losing any length. I obviously recommend an extra inch as the actress said to the bishop! Having adjusted the lengths and squaring up the collector tube and tail pipe they were cleaned up for welding. Next the parts are realigned back on the fixture carefully with the mount being relative to the flange end. At this point they are tacked together in at least 3 spots. Check it all again to make sure nothing has moved and weld the parts together. If you're using MIG to weld stainless to mild you'll want a 308 wire and Argon backing gas. We used the TIG to tack and weld. Interesting to note with a job like this most of the time is in the set up and prep. By the time it comes to switching your MIG over and paying for a spool of wire etc it really was quicker and easier to TIG them. The TIG welds are a whole lot nicer than the welds I'm seeing on all these factory pipes done with a MIG. Ceramic coating covers some sins but the MIG welds have got holes and inconsistencies in them that the ceramic coating doesn't hide. A good MIG welder would do a bang up job on these I'm sure and they are really good for filling in dents and disc pad sanding them back before coating. Most of these pipes suffer a little underbelly roadrash. I'll show you guys what we saw side by side on the old and new mufflers. Stay tuned

[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.

[bigrob]

My motor is rated at 375 HP and dyno'd 306 at the wheels, which is cool for me. But.....more power is ALWAYS a welocome friend. And louder would be cool too....I think FYI I had a 5.0 mustang years back and removed the mufflers and the car definitely felt slower. Had the same issue on a newer Tang GT when mufflers were removed. Not sure if I lost HP or torque, maybe both. I rememeber reading you usually lose one or the other when tweaking your exhaust system.

[mickmate]

OK so here's a good side by side comparo of the SPF stock pipes compared to the specialty stainless bad boys

The stock mufflers were not only very small on the ID they had also been crushed across to restrict them even further. The cross section of the ID at the most restrictive parts measured about 3/4" x 1 3/4".
Having cut, trimmed and squared off the pipes cuts it was simply a matter of reinstalling the components in the jig. As I said tack them in a few places and I try and skip around with my welding. That does a couple of things, most importantly dispersing the heat so you don't finish up with banana pipes and also for ease of weld positioning and a nicer resultant bead. Then it's off to my pal Zac http://www.directcoating.com for the ceramic coating process. He tells me sidepipes are not easy to do. The reason for that is they are long (obviously) and when they have been ceramic coated, which is brittle by nature. They have to be finished with a polishing/burnishing media by tumbling. That can cause chips and dings in all the nice work we've done. The good thing about it is that these guys do top notch work and can rework if necessary always with super results. He has redone "other" peoples work for me as well as some superb systems we have built for Hot Rods. Doug had a good solution to avoiding shipping damage which is also a serious consideration with these things. He took his to the UPS store and said "package and send em". They did a great job for fairly short money compared to the pipes value and wrapped them up really well in a guitar box.

[RedBarchetta]

Originally Posted by mickmate

Mick, consider some sort of transition cone insert to allow the exhaust to overcome the abrupt 90* weld of the new inner muffler. I whipped up this sketch for someone else here as an example:



Without it you will experience some "fluttering" when letting off the gas. Not as pronounced under moderate acceleration between shifts, but you will definitely here it when you approach stop lights. Very annoying. If I had the money I'd rip out my existing pipes and start over.

My $0.02.

-Dean

[cdnus]

Dean,
I was able to get out yesterday for my first run with the replacement s/s mufflers. They did relace the defective mufflers N/C, but my cost for shipping & re & re mufflers was about $540.00 can. + my labour.
I did fab & install the transition cone in the inlet side.
If you look at the posted photo by mickmate (above) you can see the difference in the upgraded version of their muffler.
I went with the 2 1/2" core as previous & I am very pleased with the sound, I can again enjoy driving without blood running from my ears.

NOTE!
I still get that fluttering sound on de-cel below 2000 rpm. & idle, but no tweeting with this set. I did a few mid throttle spurts (roads are still pretty dirty from the last snowfall) & the sound was very nice & I did not have to wince at all.
In fact it was so smooth I found myself surprised several times when I checked the tach & saw the rpm much higher than I thought.

So far so good

Regards Craig

[RedBarchetta]

Originally Posted by cdnus

Dean,
I was able to get out yesterday for my first run with the replacement s/s mufflers...I did fab & install the transition cone in the inlet side...If you look at the posted photo by mickmate (above) you can see the difference in the upgraded version of their muffler....NOTE! I still get that fluttering sound on de-cel below 2000 rpm. & idle, but no tweeting with this set.

Regards Craig

Craig, thanks for the update. The upgraded mufflers don't look all that different to me...maybe a thicker weld bead along that 90* section to "build up" the deflection area, but I don't see much else. The fact that you are still experiencing that fluttering noise at/below 2,000rpm on d-cel, WITH THE REDUCTION CONE, concerns me greatly. Not from a performance standpoint, but just that this fluttering is a frustrating aspect that shouldn't be there.

I would suspect that the 2.5" ID are considerably quieter than the baseball-esque 3".

-Dean

[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.

[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

[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]

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?

[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

[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??

[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.