One or Two Mufflers

[Mike Mileski]

Well, I'm about ready to do my exhaust system and know that it would be simpler if I could only use a single muffler (I'm running a new Chevy ZZ 350 H.O. crate motor) as opposed to squeezing in two of them, along with the extra tubing. My worry is that a single muffler will cause serious restrictions at higher rpms. I even bought a Borla, modified it to fit using the stock hanger, and then sold it because of my concerns. Any good experience with good flowing (and not overly noisy) single mufflers out there?

[Guest kc6wfs]

Hi Mike,

 

I'm running a single FlowMaster 2 stage with 3" pipe and don't seem to have any restriction. Noise is not to bad until WOT.

You can hear it on my geocities.com web page below.

 

Dave

 

 

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www.geocities.com/kc6wfs/240z.html

www.NitroPhotos.com

[DavyZ]

Mike, although I have not installed it yet, I bought a 3" single system from Rick Johnson. According to Rick it is very close to running a double. Why? It is built right! Two mandrel bent 2.5" down pipes go to an efficient Y-pipe (you can use a Flowmaster Y-pipe for this) that dumps immediately into a stainless Borla (straight thru design) and then to a mandrel bent 3" pipe, ending in a large Dynomax Superturbo(?) muffler with chrome tip. The Dynomax has 3" internal flow directors NOT the restricted smaller ones. This package flows so well according to him, that when he switched to a similar 3.5" system, there was no difference in power. The system is quiet, which is what I want, flows well, and is a single (read: simple to install) system as well. Just by looking at this system, I know it is a winner and will suit me right up to 400hp (and maybe higher)with no worries.

 

Now the only concern of mine is if my block-huggers are up to the task. I would go with the full-length units next time although they are considerably more expensive. Just my $.02

 

David

[BLKMGK]

We've talked about this some before - due to the fluid dynamics involved a single 3inch pipe flows as well if not slightly better than a pair of 2.5's. There are plenty of mufflers out there that should work without sacrificing too much power and the system Davy described does sound pretty good. Headers are where you may actually lose some HP but honestly I'm willing to sacrifice a little power here and there to wind up with a car that's comfortable both to drive and to service.

 

While I think about it - there are several companies that make OVAL pipe. If ground clearance is a concern look around at some of the circle track types of catalogs or in the back of some of the Chevy mags to find these puppies. I THINK Spintech may be one of the folks advertising this stuff. Worth a look anyway...

[Guest Anonymous]

I have heard that if you go the dual pipe route it is best to bolt and not weld so you can still gain access to the trans and certain other components that the pipes may restrict access to. After a little research I have decided on a single 3" to go with my LT1. But that's just mu opinion. good luck.

Craig

[Guest Rick Johnson]

I built the 3 1/2" system discussed earlier (it is 3 1/2 with mandrel bends all the way back to the 3" Dynomax Turbo Muffler). I tucked it in real tight and it does not hang down too bad. It did not make more power than the 3 inch system. For the strip I plan on exchanging the 3" Dynomax for a straight thru design which will simply bolt in because I flange mounted this rear section. When I make this change I will let you all know if it makes more power.

 

I must add that if you want a truly quiet system you must use 2 mufflers in series. I built the new 3 1/2" system with only a Dynomax in the rear and it resonates loudly below 2000 RPM. My preference for an additional resonator is the Borla Multi core muffler. It's 4 1/4 x 7 7/8 case is small enough to fit under the driveshaft. It is very pricy but it is quiet while offering a straight thru design.

[Modern Motorsports Ltd]

quote:

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Originally posted by Rick Johnson:

I must add that if you want a truly quiet system you must use 2 mufflers in series. I built the new 3 1/2" system with only a Dynomax in the rear and it resonates loudly below 2000 RPM. My preference for an additional resonator is the Borla Multi core muffler. It's 4 1/4 x 7 7/8 case is small enough to fit under the driveshaft. It is very pricy but it is quiet while offering a straight thru design.

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Rick, I"ve experienced your resonance on two systems now. It was only absent on the one I had a resonator on and that was too restrictive (poorly bent/made system as well!). What setup/header sizes/motor/any dyno data did you run with the 3" setup with borla resonator you describe?

 

My new system is going to be a single pipe still but dual mufflers/bottle of some sort/undecided as of yet. It HAS to be quiet at cruise and mild throttle especially up to 2500rpm. My setup after other mods sitting on my shelf will be 3-325rwhp (1-3/4" headers). Money is a concern but not a real limit after past two systems SUCKED for my purposes and I'm now mor knowledgeable on pros/cons.

 

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Of all the things I've lost, I miss my mind the most.

[Guest Rick Johnson]

Ross, I have a medium performance 383 wiith a 700R4. I have 1 3/4 inch tube long headers into 2 1/2 collectors into 2 1/2 mandrell bent pipes. They used to merge into a single 3 inch pipe which went directly to a 3 borla multi core muffler (bodyy size 4 1/4 x 7 7/8 x 16" long). It then continued back thru 3" mandrel bends to a 17793 3 inch Dynomax turbo muffler. This system had a reasonable sound level but would not get you in noise trouble. The only slight resonant point was right at 1800 RPM. G-Tek claimed 295 average rear wheel horsepower.

 

My new system uses the same 2 1/2 pipe but goes into a flowmaster Y connector into a 3 1/2" mandrel pipe all the way back to the same 3 inch style Dynomax muffler.

 

The sad truth is the system is way too noisey without the borla multi core in the driveshaft tunnel. It currently resonates from about 1000 to 2000 RPM. And the G-Tek assures me the power is very similar - maybe up a few HP on average but not over 300.

 

This weekend I will install a 3 1/2" borla multi core in this system (unfortunately I only have room for the 12" long version. I hope all the resonance is gone???

 

Unfortunately borla no longer makes the 3 inch version of the multi core, instead you would have to use the sportsman muffler which is much cheaper but not quite as quiet (it is not multi-core).

 

In the future - if Irwindales' 1/8 mile track is fun - I will build a 3 1/2" straight thru muffler which will flange mount to my existing sytem replacing the Dynomax when I go racing and dont mind the noise. At this point I believe my system will be as efficient as anyones dual 2 1/2 system -- probably better.

 

Hope this helps

[BLKMGK]

Drawing on my Mustang experience here... Mustangs coe from the factory with two mufflers and a true dual exhaust. Look closely at the stock mufflers - they're different sizes! IF you use two mufflers of the same size the droning at cruise will drive you mad. It's a roar that goes from the front of the car to the back in endless cycles of highway driving - you'll know the true meaning of headache if you run a pair of old style two chambers with this setup like I did!

 

So, if running dual exhaust try running a different muffler on each side to help cancel out the sound. I ended up putting turbnos on that car which killed the noise perfectly with those same mufflers. Now without turbos I've got Dynomax mufflers on there and the noise is perfect IMO with no drone that I've noticed. Probably sacrificed some sound but hell I'll gladly give up 10hp to gain that much comfort!

[Andrew Bayley]

I totally agree with what Jim said.

One pipe resonating is bad. Two pipes resonating at the same time is painful!!! I used to have a Cadillac that I experimented with true duals. First, I ran two equal lenght glass packs half way back in the trans tunnel. Very loud, tons of resonation. Next I put two more equal length glass packs right at the back of the exhasust system. It became quiet, but there was still quite the drone. Then one day, out of dumb luck, one of my tailpipe glass packs fell off. Instead of replacing it with the same sized (18") muffler, I opted for the smaller 12" one. To my surprise, the resonance was gone. Also, the tone of the exhaust was much more smooth.

 

Anyway, I was wondering if anybody knows of a source where I can get 4" mandral bent exhaust pieces. I've been considering the single exhaust route again. Two pipes would look cool, but single would be cheaper and easier ( a little more "stealthy" as well ).

 

-Andy

 

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"But I don't sit idly by,

I'm planning a big surprise."

 

Andrew's Land of Z and Honey

[Guest Fast Frog]

Gentlemen:

 

Before you go out and buy those 2" headers and that 3" or 4" exhaust systems that may or may not tie into a single big pipe and muffler, check out the tech specs and info on Sanderson's web sight!! (www. Sandersonheaders.com) Like carburation, the tendency is "bigger is better". I got my eyes opened by visiting Sanderson's web site!!

 

Rick

[Guest Rick Johnson]

3 1/2, 4 and larger mandrel bend pipe can be found at a truck parts store. In LA we have Fleet Supply and they have a great selection of short and wide radius mandrel bends.

[Modern Motorsports Ltd]

quote:

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Originally posted by Rick Johnson:

Ross, I have a medium performance 383 wiith a 700R4. I have 1 3/4 inch tube long headers into 2 1/2 collectors into 2 1/2 mandrell bent pipes

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Great info Rick and others. My build is 'intended' to have same power as yours was putting out. I want mine literally quiet if possible at cruise and mild throttle (ie. cruising on the highway and you need mild throttle to pass occasionally or just maintain changing speed in traffic). What would you reccomend to knock the noise down one more notch from what you had? I want this car to finally be comfortable for my wife to go on long trips with me and the sound is one of a few remaining roadblocks. (car is soundproofed on front half/rear remains to be done, I want the exhaust quieter as well). At full throttle it can growl somewhat but 90% of the time being quiet is fine by me, a lot less police attention is attracted let alone I prefer the stealth factor for security as well.

 

 

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Of all the things I've lost, I miss my mind the most.

[BLKMGK]

Start by soundproofing the rear! I was flat out amazed at how much quieter my car was when I put in the soundproofing. Hunt up the thread where I posted about that and check out some of the URLs others provided for cheaper sound proofing materials. I think I really like the bedliner idea too

 

As for quiet mufflers, I think the Dynomax mufflers are pretty good and keep my Mustang pretty quiet. They might sacrifice some power but it's worth it IMO. This car might get their stainless ultras if I can't find ricer mufflers on the cheap. I expect those to be louder than their regular mufflers though.

 

Hrm, you running dual? A crossover pipe? X pipes are supposed to be good for quieting things down. Where's a good place to get a cheap X? Dr. Gas sells them but they're a bit pricey I've been told....

[Guest Rick Johnson]

Ross,

I just got back from an afternoon of driving my car with the additional Borla in series with the Dynomax in back.

Reminder - 2 1/2 pipes into; flowmaster Y connector; into the Borla multicore 3 1/2 in/out 12" long; into 3 1/2 pipe and mandrel bends; into 3" Walker Dynomax.

 

I view the system as a complete success. The resonance between 1 and 2000 RPM is completely gone after the addition of the 12" Borla. The noise level is acceptable to my critical ear - I hate noise.

 

Interestingly, it does not seem to have any resonant points at all. The last 3" system with a 16" Borla and 16" Dynomax had a real short resonant point at 1800 RPM. Maybe the talk above about different size mufflers applies to mufflers in series as well. Maybe the smaller Borla (12" long) is a better match for the 16" Dynomax in the rear???

 

I built it myself and must warn anyone duplicating this system that these components barely fit and patience or a good muffler man will be required.

 

I recommend having a flange near the Dynomax so you can drop the system down to work on the trans etc. Additionally, you could bolt on a straight thru muffler to pick up those last few ponies at the track.

[Modern Motorsports Ltd]

quote:

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Originally posted by BLKMGK:

Start by soundproofing the rear!for cheaper sound proofing materials.

 

Hrm, you running dual?

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The rear will be soundproofed, that's a given. I've been using Proform heat shield pads and sound pads/v. pleased with price and performance. Made a huge difference in heat and sound, can't roast burgers on my tranny tunnel any more but it was a worthwhile tradeoff

 

Single exhaust as described up above. I do recall your sound proofing thread and sources/including an auction site that routinely had kits at good pricing AIR.

 

 

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Of all the things I've lost, I miss my mind the most.

[Rob]

I really like my 3" single exhaust and Edelbrock (I think its called) 304 series muffler. It sounds very cool, I get lots of compliments on it. Not too loud, but you can definitely hear it. It fits nicely in the stock location. I also have the ZZ4 crate motor. For under 400 HP I think you are OK with single 3" if the system is designed correctly. I would recommend buying a good flowing Y connector from flowmaster or similar rather than relying on the skill of the muffler shop in this critical area.

 

One other thought, the dual exhausts really hurt the sleeper look. Nothing wrong with that, but it could be a consideration. I love surprising people. Any gear head can tell I have a V-8 from the sound of my exhaust though.