Quietest Boosted Exhaust?

Jayhovah · 04-27-2017, 12:55 PM

Based on the discussion in this thread, Chase, I think you should probably just add some turbos.

Kzonts · 04-27-2017, 12:59 PM

Bringing up the GTR exhaust again, just as an example. It has two sets of cats and a "Y" pipe, etc... Hell, if it takes this much engineering to reduce the sound, just remove the SC. You built a race car and it comes with a certain decibal level... LOL

MoulaZ · 04-27-2017, 02:23 PM

Quote:

Originally Posted by bcfromfl

When you say that "they didn't have too much of an effect," do you mean on boost pressures (i.e. restricting the exhaust and increasing boost), or on sound levels, or both?

Sound level. Didn't notice any difference in power/boost at all.

Quote:

Originally Posted by jmroy6

GESI makes a nice high quality drop in cat that will withstand the high egts from boost. i know Seb tuned a nismo 370z with these cats on a stillen sc and had good results.

link https://www.vibrantperformance.com/c...Path=1527_1326

Jeez, for those prices you might as well just buy another whole system!

Krylon · 04-27-2017, 11:16 PM

Quote:

Originally Posted by jmroy6

GESI makes a nice high quality drop in cat that will withstand the high egts from boost. i know Seb tuned a nismo 370z with these cats on a stillen sc and had good results.

link https://www.vibrantperformance.com/c...Path=1527_1326

I've got 2 Vibrant GESI 7530's. They are placed at the end of the downpipes close to the flange.

Quote:

Originally Posted by MoulaZ

Jeez, for those prices you might as well just buy another whole system!

It hurt the wallet but I'm hoping to not have to replace these. Sounds good with a 3" exhaust, etc.

ChaseZ · 04-28-2017, 12:18 AM

Quote:

Originally Posted by Jayhovah

Based on the discussion in this thread, Chase, I think you should probably just add some turbos.

Sounds good. Send me yours

Boosted Performance · 04-28-2017, 01:14 AM

I built this a long time ago for my 350Z:

The two mufflers in the rear were very large straight flow through design, and for that reason along with the turbo, the exhaust was as quiet as stock. This is with aftermarket equal length headers, and of course no catalytic converters.

I have since built this:

3.5" piping from where the OEM Y-pipe would end, splitting in to dual 3". This is all aluminium, and weighs in at 12lbs. It is of course louder, but not as loud as one would think.

Also did a single 3.5", which is a bit more rowdy

it came in at about 8lbs :

Sound clip of the single 3.5" splitting in to dual 3.0"

http://vid137.photobucket.com/albums...psueffzhrq.mp4

Sound clip while on the lift single 3.5":

http://vid137.photobucket.com/albums...pscleukp0r.mp4

MoulaZ · 04-28-2017, 01:45 AM

Quote:

Originally Posted by Boosted Performance

I built this a long time ago for my 350Z:

The two mufflers in the rear were very large straight flow through design, and for that reason along with the turbo, the exhaust was as quiet as stock. This is with aftermarket equal length headers, and of course no catalytic converters.

I have since built this:

3.5" piping from where the OEM Y-pipe would end, splitting in to dual 3". This is all aluminium, and weighs in at 12lbs. It is of course louder, but not as loud as one would think.

Also did a single 3.5", which is a bit more rowdy

it came in at about 8lbs :

Sound clip of the single 3.5" splitting in to dual 3.0"

http://vid137.photobucket.com/albums...psueffzhrq.mp4

Sound clip while on the lift single 3.5":

http://vid137.photobucket.com/albums...pscleukp0r.mp4

Love that first one, any clips of that one?

And for the size I was expecting a lot more noise for those last two. Nice work!

I'm waiting to finish rebuilding my SC, before I do another recording under the same circumstances of my pre-SC recordings for a reasonable comparison. Right now the car starts, but the SC is on my bench awaiting new seals & bearings hah.

Boosted Performance · 04-28-2017, 01:57 AM

Quote:

Originally Posted by MoulaZ

Love that first one, any clips of that one?

And for the size I was expecting a lot more noise for those last two. Nice work!

I'm waiting to finish rebuilding my SC, before I do another recording under the same circumstances of my pre-SC recordings for a reasonable comparison. Right now the car starts, but the SC is on my bench awaiting new seals & bearings hah.

Sorry, don't have sounds clips of the first one. It is basically stock sounding. With that exhaust, all you hear is the turbo.

ChaseZ · 04-28-2017, 02:11 AM

Quote:

Originally Posted by MoulaZ

I'm waiting to finish rebuilding my SC, before I do another recording under the same circumstances of my pre-SC recordings for a reasonable comparison. Right now the car starts, but the SC is on my bench awaiting new seals & bearings hah.

Ditto. Got my new seals and bearings here just need to get to the R&R.

ChaseZ · 04-28-2017, 02:18 AM

Quote:

Originally Posted by Boosted Performance

( Click to show/hide )

3.5" piping from where the OEM Y-pipe would end, splitting in to dual 3". This is all aluminium, and weighs in at 12lbs. It is of course louder, but not as loud as one would think.

( Click to show/hide )

Sound clip of the single 3.5" splitting in to dual 3.0"

http://vid137.photobucket.com/albums...psueffzhrq.mp4

Maybe I need a 3" test pipe instead of 2.5

Or bring my car up a couple days before seb's dyno day in June and you can whip me up an exhaust like that one..

TopgunZ · 04-28-2017, 08:47 AM

Dang Sasha. You should start a BP exhaust option with your kits, or others. Those look great!

Boosted Performance · 04-28-2017, 09:43 AM

Quote:

Originally Posted by ChaseZ

Maybe I need a 3" test pipe instead of 2.5

Or bring my car up a couple days before seb's dyno day in June and you can whip me up an exhaust like that one..

For sure, I'd be able to help you with that.

Go full aluminium once you are out of the heat range of the turbo, I really like the tone on my own car. Dual 3" with 4 mufflers.

I also use 3mm wall aluminium tubing on the exhaust, not the typical Vibrant paper thing crap. It will last a very long time.

Quote:

Originally Posted by TopgunZ

Dang Sasha. You should start a BP exhaust option with your kits, or others. Those look great!

Yeah, I had a bit of a feeler for the aluminium exhaust, but there wasn't all that much interest.

Jayhovah · 04-28-2017, 11:20 AM

Quote:

Originally Posted by ChaseZ

Sounds good. Send me yours

But then my car will be too loud!

bcfromfl · 04-28-2017, 12:51 PM

I thought I was understanding that the consensus leans towards turbos being generally quieter than s/c (although depending upon a host of variables), but in this thread it seems that turbo and s/c exhaust systems are being compared interchangeably.

If there IS a difference in sound levels between the two systems, how can the s/c exhaust be modified to reduce some of this additional noise? Maybe I'm in the minority, but I'd like to see some configuration that keeps the decibels to a manageable level. Seems like the cats are a key component to reduce some of the worst of the noise, but they should be repositioned downstream to avoid the worst of the heat? Is that right? Where would you place hangers, etc.? Will the sensors need additional cabling to reach? Other problems?

I found a suggestion on one website that recommended adding spiral inserts inside straight pipes to reduce excessive noise. Has anyone tried something like this?

I tried Googling the images of the exhausts of factory s/c cars, but that didn't really yield helpful results. Are factory s/c cars known to burn through cats?

Jayhovah · 04-28-2017, 12:59 PM

Quote:

Originally Posted by bcfromfl

I thought I was understanding that the consensus leans towards turbos being generally quieter than s/c (although depending upon a host of variables), but in this thread it seems that turbo and s/c exhaust systems are being compared interchangeably.

If there IS a difference in sound levels between the two systems, how can the s/c exhaust be modified to reduce some of this additional noise? Maybe I'm in the minority, but I'd like to see some configuration that keeps the decibels to a manageable level. Seems like the cats are a key component to reduce some of the worst of the noise, but they should be repositioned downstream to avoid the worst of the heat? Is that right? Where would you place hangers, etc.? Will the sensors need additional cabling to reach? Other problems?

I found a suggestion on one website that recommended adding spiral inserts inside straight pipes to reduce excessive noise. Has anyone tried something like this?

I tried Googling the images of the exhausts of factory s/c cars, but that didn't really yield helpful results. Are factory s/c cars known to burn through cats?

There is definitely a difference in noise having turbos in the exhaust stream and its a very significant one. Exhaust sound, heat, velocity... energy in general, are soaked up by the turbo.

There is a lot of good discussion on this thread.. but for the sake of discussion we've probably overthought it quite a bit (which is healthy as it helps us all gain more knowledge....one of the primary purposes of this forum!)... I think if you just go with one of the quieter exhaust systems that follow the OEM design (allows for much larger muffler) and some resonated test pipes (or cats somewhere in the stream), you'll be fine.

04-27-2017, 12:59 PM	#62 (permalink)
Kzonts Track Member Join Date: Mar 2015 Location: Greenville, SC Age: 61 Posts: 872 Drives: 2019 Roadster Rep Power: 200741	Bringing up the GTR exhaust again, just as an example. It has two sets of cats and a "Y" pipe, etc... Hell, if it takes this much engineering to reduce the sound, just remove the SC. You built a race car and it comes with a certain decibal level... LOL __________________ 2019 Magnetic Black Roadster FI Exhaust \| EVO-R Rear Diffuser \| Artwork Bodyshop Front Splitter \| Tuned By Specialty Z

04-28-2017, 01:14 AM	#66 (permalink)
Boosted Performance The370Z.com Sponsor Join Date: Feb 2010 Location: Edmonton, AB Posts: 1,629 Drives: Z's Rep Power: 3382	I built this a long time ago for my 350Z: The two mufflers in the rear were very large straight flow through design, and for that reason along with the turbo, the exhaust was as quiet as stock. This is with aftermarket equal length headers, and of course no catalytic converters. I have since built this: 3.5" piping from where the OEM Y-pipe would end, splitting in to dual 3". This is all aluminium, and weighs in at 12lbs. It is of course louder, but not as loud as one would think. Also did a single 3.5", which is a bit more rowdy it came in at about 8lbs : Sound clip of the single 3.5" splitting in to dual 3.0" http://vid137.photobucket.com/albums...psueffzhrq.mp4 Sound clip while on the lift single 3.5": http://vid137.photobucket.com/albums...pscleukp0r.mp4 Jayhovah, Zbrah, ChaseZ and 1 others like this. __________________ 750WHP starting @ $7,500 to the door FOR DETAILS VISIT: http://www.the370z.com/members/boosted-performance.html FB: https://www.facebook.com/Boosted-Per...6303179791462/ IG @boostedperformanceyeg Last edited by Boosted Performance; 04-28-2017 at 01:30 AM.

04-28-2017, 08:47 AM	#71 (permalink)
TopgunZ A True Z Fanatic Join Date: Jun 2012 Location: Minneapolis Posts: 2,651 Drives: 06 350Z , 09 370Z MT Rep Power: 6834	Dang Sasha. You should start a BP exhaust option with your kits, or others. Those look great! __________________ ROTREX SUPERCHARGER TUNER KITS - $6799/ CUSTOM STILLEN AIR TO AIR KITS -$2100/ 700+ WHP!! WWW.TOPGUNSPEEDWORKS.COM

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04-28-2017, 12:51 PM	#74 (permalink)
bcfromfl Enthusiast Member Join Date: Nov 2016 Location: Youngstown, FL Posts: 256 Drives: 2015 PW Nismo 6MT Rep Power: 9	I thought I was understanding that the consensus leans towards turbos being generally quieter than s/c (although depending upon a host of variables), but in this thread it seems that turbo and s/c exhaust systems are being compared interchangeably. If there IS a difference in sound levels between the two systems, how can the s/c exhaust be modified to reduce some of this additional noise? Maybe I'm in the minority, but I'd like to see some configuration that keeps the decibels to a manageable level. Seems like the cats are a key component to reduce some of the worst of the noise, but they should be repositioned downstream to avoid the worst of the heat? Is that right? Where would you place hangers, etc.? Will the sensors need additional cabling to reach? Other problems? I found a suggestion on one website that recommended adding spiral inserts inside straight pipes to reduce excessive noise. Has anyone tried something like this? I tried Googling the images of the exhausts of factory s/c cars, but that didn't really yield helpful results. Are factory s/c cars known to burn through cats?