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socorob

Quietest muffler for V8 Z?

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socorob    4

Who thinks they have a quiet exhaust, and what are you running? I have a hushpower, which I thought it meant it would be quiet. I was watching a car show on TV and the flowmaster rep was on there saying their hushpower line makes your small block sound like a big block. Exactly opposite of what I want. Mine roars too much for my taste, and would like it quiet as possible but don't know what to replace it with.

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JMortensen    235

I was looking into this with my build because I was over the db limits for the venue I was racing at. After multiple threads on different forums, the general idea that I got out of it is that you need volume inside the muffler and tight packing. The exhaust pulses vibrate the packing, turning the sound energy into heat. So the recommendation was as big a muffler as you can fit, with packing not reflectors as you would find in flowmaster or other "chamber" mufflers.

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Miles    32

I have been looking at reducing the exhaust noise on my 240Z (SBC 350, 2.5" exhaust, Flowmaster Magna Flow 14" body muffler).  The noise level is fine for city driving at low throttle opening, but approaching WOT it sounds like open exhaust and driving through parking lots sets off car alarms.

 

Here is some info I have been looking at:

 

 

http://www.dragzine.com/tech-stories/exhaust/understanding-muffler-design-and-sound-absorption-strategies/

https://www.acoustics.asn.au/conference_proceedings/AAS2005/papers/34.pdf

Edited by Miles

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socorob    4

I have the hushpower and it is loud. My wife hates riding in the Z and wears earplugs when she does. It sounds awesome at track days and when accelerating around, but is absolutely horrible at interstate speeds for anything more than a couple minutes. I have dual 2.5" going into a single 3" just before the diff, going 3" single out the stock location. Theres no dba limit at the track here, but it probably wouldn't pass if there was.

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74_5.0L_Z    9

I have Borla Pro XS mufflers on mine. I love the way they sound.  They are mellow at part throttle but scream at full throttle.

 

I've had people say that they don't mind getting passed by me because they love the way my car sounds.

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I have not fired up the LSZ with the full CXR exhaust on it but will report later.  

 

That being said, we have put auger style inserts in several cars, they cause the gases to tumble and it makes a huge difference in sound and cause very little back pressure.  The flow through mufflers with external packing all get louder with time.  We found this on the side pipes with the Factory Five cars we build.  We have replaced side pipes completely with the auger mufflers and they are a tin sound without the booming.  On my stock 240Z I put a car chemistry insert (not an auger style just baffles with no glass) in the MSA exhaust as it was too loud for the stock car and droned, it does create a bit of pressure but the stock exhaust was so much smaller than the MSA it was not a big deal.  Hope this helps.  Opinion to follow:  For the money I would get an auger insert from speedway or who ever and just stick it in a joint and see if it helps.  Richard.  

Edited by Richard Oben

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ryant67    6

I think another issue is that while you can select a muffler that will be quiet when first installed, once you've ran it hard for awhile it will start getting loud as the packing deteriorates.  My Magnaflow was borderline too loud on install, and now it's just beyond excessive.  I really need to nurse the throttle to keep the noise down in the city...

There are places that manufacture mufflers that you can open and repack as needed.  I think that will be the direction I head in next time...  

Coast Fabrication makes them, but I think you'd be looking at a custom size to get enough volume to keep the noise down, or daisy chaining a couple of them...  http://www.coastfab.com/ultra-lightweight-racing-mufflers.html

Burns makes them too, although I think it might actually be Coast manufacturing them...  http://www.burnsstainless.com/ultra-lightmufflers.aspx

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thedarkie    2

I have Borla Pro XS mufflers on mine. I love the way they sound.  They are mellow at part throttle but scream at full throttle.

 

I've had people say that they don't mind getting passed by me because they love the way my car sounds.

 

Key word being "mufflers" here.. you're doubling the canister volume by using two of them. 

 

My 363 swap is done and I had to have a new exhaust and headers made to match the taller heads - I'll be selecting a muffler soon but am only going with a single out. I have to measure the space to see what the biggest can we can fit under there is? ]

 

 

Magnaflow makes 22" long 5x11 oval mufflers with 3.5" in/out, does anyone have something of similar size and can comment on noise? Definitely DON'T want to be setting off car alarms. 

Edited by thedarkie

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RebekahsZ    106

To reduce noise, go to shortie headers if cast iron won't fit and reduce pipe diameter. I'm building a street rod and after how loud my truck is with long tube headers and 3" exhaust, I'm going with cast manifolds and probably 2" dual exhaust with a crossover. After a while, loud is just...loud.

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thedarkie    2

To reduce noise, go to shortie headers if cast iron won't fit and reduce pipe diameter. I'm building a street rod and after how loud my truck is with long tube headers and 3" exhaust, I'm going with cast manifolds and probably 2" dual exhaust with a crossover. After a while, loud is just...loud.

 

Don't know that I'd be willing to compromise so much of the performance-side of exhaust design just to quiet it down. Don't you think it'd be better to hang onto longer primaries and more pipe volume, and just stick on a larger muffler at the end? 

 

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mtnickel    12

Good watch on exhaust size : power relationship.

 

https://youtu.be/_PVXvHkr-Vs

 

Makes me really rethink having just a SINGLE 2.25" axle back on my 300 odd HP subaru. But I too like it quiet. May have to look at trying the Dynomax VT as one member above mentioned. They are surely quiet, but can be a little "unnatural" sounding as the spring flapper opens and closes.

Also a good watch on Cast vs short vs long tube headers:

 

https://youtu.be/Y7_lSU3D0jw

 

and while we're on the subject, this one on dented headers blew my mind. Don't be scared to take a mallet to anything :P

https://youtu.be/azPKIjxmmdU

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thedarkie    2

^^ good reminder, totally forgot about those videos.. the header one is appropriate for me - just goes to show how much power is lost/gained on a 500hp motor when going from cast shorties to mid length to long tubes.... in conclusion: not much!!! 10 horsepower lost or gained at 500, in a 2500lbs car, really won't make much difference. 

 

I don't think Im gonna sweat the details of packaging my custom headers, just gonna let the fabricator do his thing... it really won't matter in the end. 

Edited by thedarkie

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mtnickel    12

Just measured my old exhaust that I had on a mild 5.0 swap.

 

It was shorty headers into dual 2.5" pipes merging into single 2.5". Muffler oval 5x11 by 14" long with 2.5" in-out. The car wasn't obnoxiously loud at all just FYI. 

Ya. As per the videos again, the 2.5" they said was really really quiet. So a single 2.5" I can imagine would be really quiet (depending the design).

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Savage42    21

I have a dual 2.5" mandrel bent tubing with x-pipe going all the way back to a Magnaflow dual in / 3" outlet in the stock location.  I went with thicker 14 gauge tubing to keep noise down. 

 

This is a video from the outside:

 

This is inside my car with my iPhone 7 and a blast at 70% throttle in 2nd gear.  Quieter than I expected: 

Edited by Savage42

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JoeK    2

I have a dual 2.5" mandrel bent tubing with x-pipe going all the way back to a Magnaflow dual in / 3" outlet in the stock location.  I went with thicker 14 gauge tubing to keep noise down. 

 

 

Gary,

 

Do you happen to have any pics of the underside of the car with this exhaust installed?

 

Thanks, Joe

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RebekahsZ    106

The issue of sound control is really affecting the hot rodders who autocross. SCCA (and many road courses) is having to enforce noise limit (dB)standards. When I was autocrossing, I had to pedal the car when in proximity to the dB meter. If I were to really pursue autocross, I imagine my fix would be (either to run a stock Miata in stock class, or) to mount a huge (like 4' long) RV muffler cross-wise from the rear bumper mounts external to the car. Something I could install with v-bands the night before the race. I don't know if it would be better to direct the outlet straight toward the sky, straight back, or straight at the ground.... but getting scolded for having a car that sounded as good as it looked and ran (perhaps with a better driver) really sucked the fun out of hanging with the SCCA crowd. It's not their fault-they are just doing what they gotta do to keep the facility.

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calZ    1

You could also do it Laguna Seca style. Put an elbow on the back that you can change the direction of. Figure out which side the sound meter is on and point the exhaust up and away from it.

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Savage42    21

Gary,

 

Do you happen to have any pics of the underside of the car with this exhaust installed?

 

Thanks, Joe

I don't have a shot while on the rack, but this may help. I copied a friend's car that has an old school SBC with the same piping & muffler and it sounded good, as well. Not the prettiest, but functional and didn't cost me a fortune.

post-505-0-37702800-1488403864_thumb.jpg

post-505-0-71237400-1488403947_thumb.jpg

post-505-0-54487200-1488404003_thumb.jpg

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It's going to end up with how much HP are you willing to trade off for being quiet.

 

When I decided on the layout for my car, after digging it seemed that glass-pack type mufflers were the best balance of performance vs sound reduction.

 

I read through a bunch of Vizard and other's stuff.  Actual testing across manufacturers on the same setup is shockingly difficult to find.  Half the articles about mufflers cite professionals from one company or another who always insist their own design is best.

 

I did find this post when I was looking: http://www.bangshift.com/forum/forum/bangshift/tech-section/3202-some-muffler-test-info

 

I ended up with a pair of these https://www.summitracing.com/parts/sum-633222 tucked up next to each other where the stock muffler should be.  I don't think what I did will fit with the stock bumper shocks.

 

20160813_173951_zpslruoyzn2.jpg

 

I have this video, but, I have no idea how much normalization my phone does by default for sound being recorded.  It is noticeably quieter when the car is actually on the ground.  And probably because you're then much higher than the exhaust compared to where my phone recorded this from.

 

https://youtu.be/5B2p1C9UAK4

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720fast    0
Posted (edited)

 Here is my 77 280 with 2 1/4 in back to the diff then 2 1/2 to chambered muffler. I do not have carpet just two rubber mats. I have to roll down my windows to here exhaust, and I have 60,000 miles on the muffler it was put on in 2014 I had a turbo muffler before that.

 

 

 

 

Edited by 720fast

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