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Yet another 3800SC exhaust build by gtoformula
Started on: 03-25-2014 08:55 AM
Replies: 25 (1863 views)
Last post by: longjonsilver on 12-07-2020 09:07 AM
gtoformula
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Report this Post03-25-2014 08:55 AM Click Here to See the Profile for gtoformulaClick Here to Email gtoformulaSend a Private Message to gtoformulaEdit/Delete MessageReply w/QuoteDirect Link to This Post
This past weekend I put over 400 miles on my car (1986 GT 3800SC 5spd). The exhaust noise was intense and I've decided to install a new system. In the image below you can see how the mufflers are currently arranged. I didn't install this system, but it is basically a down pipe from the rear manifold, to a "T" split, two bullet mufflers and then dual tailpipe tips (no resonator). I have researched several threads on exhaust builds and have listed them below ... gathered several ideas from these and will use them to create my own.

Here's basically what I'm going to do:
- my system will end up looking a lot like the system JamesCurtis put together (link below). It will have a flex pipe coming off the first bend by the manifold flange.
- I am going with a Magnaflow #12158 muffler. Seems like it is quieter than the FlowTech Afterburner and is just a bit longer (1"). I like the Hedman Hot Tips that Darth Fiero used, but I can reuse my current tips and save some bucks.
- revin had a great idea in using the exhaust donuts that are available on eBay. These provide a nice mandrel 180* small radius which will save room and eliminate some welding too.

Here's my shopping list:
- 2 1/2" Summit flex pipe #SUM-652510 $38.13
- 2 1/2" ebay exhaust donut $38.00
- Magnaflow muffler #12158 $105.62 (2 1/2" inlets and outlets)
- Dynomax Performance 2 1/2" exhaust pipes #42596 $10.97 (muffler to tailpipes)
- Dynomax Performance 2 1/2"-2 1/4" exhaust reducers 41961 $4.97/@ (tailpipes/tips are 2 1/4")

I'll cut off the flange that is currently welded to the system and bolts to the manifold. The exhaust donut will be cut in half ... one half will form the U-bend connecting the muffler inlet to the flex pipe outlet. Part of the other half will be used to connect the manifold flange to the inlet side of the flex pipe. The straight exhaust pipes will connect the muffler outlets to the 2 1/4" reducers. The current tailpipes already have 90* radius bends so all that I'll need to do is weld them to the exhaust reducers.

I'm hoping to end up with a much better sound. I don't expect, or want, a quiet system ... that's not why I bought the car. What I do want to get rid of is the way loud, and not great sounding, bullet muffler system. I'll have about $215 with all the basic parts and will enlist my neighbor's welding skills. As always, your thoughts, ideas and opinions are welcome.

_


JamesCurtis
http://www.fiero.nl/forum/Forum2/HTML/129145.html

revin and Darth Fiero (first image)
http://www.fiero.nl/forum/Forum2/HTML/123782.html

Alex4rmula
http://www.fiero.nl/forum/Forum2/HTML/121048.html

qwikgta
http://www.fiero.nl/forum/Forum2/HTML/123378.html
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solotwo
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Report this Post03-25-2014 07:48 PM Click Here to See the Profile for solotwoSend a Private Message to solotwoEdit/Delete MessageReply w/QuoteDirect Link to This Post
I bought a car last year and was told it has 3" . I asked about changing to 2 1/2 and was told ":you dont want to do that". so how does yours run with 2 1/2?
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gtoformula
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Report this Post03-25-2014 08:19 PM Click Here to See the Profile for gtoformulaClick Here to Email gtoformulaSend a Private Message to gtoformulaEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by solotwo:

I bought a car last year and was told it has 3" . I asked about changing to 2 1/2 and was told ":you dont want to do that". so how does yours run with 2 1/2?


Can't say yet. I am in the process of ordering parts. You may want to review the thread links i included. Most of them are running 2 1/2" systems. 3" may be a good idea if you're running heavy mods, but probably not necessary for my low mod set up.
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solotwo
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Report this Post03-25-2014 08:54 PM Click Here to See the Profile for solotwoSend a Private Message to solotwoEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by gtoformula:


Can't say yet. I am in the process of ordering parts. You may want to review the thread links i included. Most of them are running 2 1/2" systems. 3" may be a good idea if you're running heavy mods, but probably not necessary for my low mod set up.


My car came with a bone stock 3800SC
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gtoformula
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Report this Post03-25-2014 09:03 PM Click Here to See the Profile for gtoformulaClick Here to Email gtoformulaSend a Private Message to gtoformulaEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by solotwo:


My car came with a bone stock 3800SC


Mine too. This will be one of the mods I do. All the mufflers installed in the thread links are 2 1/2" except the Flowtek Afterburner and it only a had 3" inlet with dual 2 1/2" outlets.
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gtoformula
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Report this Post04-01-2014 01:14 PM Click Here to See the Profile for gtoformulaClick Here to Email gtoformulaSend a Private Message to gtoformulaEdit/Delete MessageReply w/QuoteDirect Link to This Post
OK. Got the parts last night and disappointed with the muffler. The Magnaflow is a beautifully constructed piece, but I don't think that the inlet/outlet arrangement will work. The Summit specs say that it is reversible, but not for how I intended to install it. There is a center inlet on one side and two offset outlets on the other side. I had intended to use on of the offsets (on the side that has two) and use two outlets ... one from each side. It doesn't look like it is plumbed for that set up. Gotta return the muffler and maybe some of the pipes and start over again.
Requesting recommendations:
Flowtech Afterburner part #50363FLT. This will work regarding the inlet/outlets, but it has one 3" inlet and two 2.5" outlets. The 3" throws a curve into my pipe plumbing and that muffler will also be louder than the Magnaflow ... I think.
Spintech 333SC - just spoke with them on the phone. Their inlet/outlet arrangement is perfect for what I have planned. One offset inlet with two opposed outlets (one on either side straight across). The standard dimensions of this muffler are 4"x10"x15"L. I have heard that 15" may be too long (13" to 14" being preferred). Spintech offers a 13" version that will obviously be somewhat louder. Opinions on whether I can go with the 15" or play it safe with the 13"?
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nosrac
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Report this Post04-01-2014 03:47 PM Click Here to See the Profile for nosracSend a Private Message to nosracEdit/Delete MessageReply w/QuoteDirect Link to This Post
You got the wrong magnaflow. The correct one is the transverse Camaro muffler.
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Tom Slick
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Report this Post04-04-2014 08:13 PM Click Here to See the Profile for Tom SlickClick Here to Email Tom SlickSend a Private Message to Tom SlickEdit/Delete MessageReply w/QuoteDirect Link to This Post
here is how Darth did mine, since you were asking.

This images is larger than 153600 bytes. Click to view.
This images is larger than 153600 bytes. Click to view.

[This message has been edited by Tom Slick (edited 04-04-2014).]

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JamesCurtis
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Report this Post04-05-2014 03:06 AM Click Here to See the Profile for JamesCurtisClick Here to Email JamesCurtisSend a Private Message to JamesCurtisEdit/Delete MessageReply w/QuoteDirect Link to This Post
I'm sorry I posted a photobucket photo. It is a broken link for me. Here's a photo below to show you what I have:



It has a bit of a drone to it when it's wrapped up at 2500 rpm on the highway/interstate. I've been thinking of running a system that followed the stock fiero route to get a little more length in the pipe. I also don't like how low this exhaust sits below the cradle. My muffler is definitely the lowest point of my car due to the lack of a tight radius coming off of the rear manifold down into the muffler.

------------------

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Report this Post04-05-2014 04:16 PM Click Here to See the Profile for Diamond DaveSend a Private Message to Diamond DaveEdit/Delete MessageReply w/QuoteDirect Link to This Post
Nice job Tom how does it sound? I love my magnaflow. Sound is incredible.
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Tom Slick
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Report this Post04-05-2014 06:13 PM Click Here to See the Profile for Tom SlickClick Here to Email Tom SlickSend a Private Message to Tom SlickEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by Diamond Dave:

Nice job Tom how does it sound? I love my magnaflow. Sound is incredible.


wonderful
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gtoformula
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Report this Post04-27-2014 03:40 PM Click Here to See the Profile for gtoformulaClick Here to Email gtoformulaSend a Private Message to gtoformulaEdit/Delete MessageReply w/QuoteDirect Link to This Post
OK. All the parts have arrived and I'm about to begin the cut 'n fit process before I weld it all up. Thanks to all that have contributed ideas/suggestions.

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gtoformula
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Report this Post05-03-2014 06:22 PM Click Here to See the Profile for gtoformulaClick Here to Email gtoformulaSend a Private Message to gtoformulaEdit/Delete MessageReply w/QuoteDirect Link to This Post
Well, I finally had time to complete this project. Below are the pictures I just took of the completed system. There are two pics of the exhaust after everything was welded and two more after I painted the system with high heat ceramic paint. Note that I did not paint the stainless flex joint. The last picture is of the car with everything completely assembled. The muffler hangs down just so that it is exposed, but it is actually just a bit higher than the rear anti sway bar that I installed.

I'd also like to give a shout out to several forum members that provided input and suggestions: Darth Fiero, jfrost, nosrac and revin who was nice enough to reply to my many messages. Sorry if I left anyone out. Thanks guys!

It went together well, but it's still louder than I expected. I am considering installing the Hedman Hot Tips resonator/exhaust tips. Does anyone have experience with these resonator tips or another type of resonator that can be installed in place of the tailpipes? I'd like to make it a bit quieter, but don't want to mess with the muffler that I just installed. BTW, the Spintech muffler is really a nice piece. Never seen anything like it before. Very complex internals that are all steel and have no way to blow out. Should last forever.





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Report this Post05-03-2014 10:48 PM Click Here to See the Profile for JamesCurtisClick Here to Email JamesCurtisSend a Private Message to JamesCurtisEdit/Delete MessageReply w/QuoteDirect Link to This Post
I must say that your exhaust snugs up much better than mine does - nice work! I like the sound of the exhaust I have at idle and part throttle but it is a little loud going down the interstate. May I ask where you got the two 180* sections and what size of downpipe you used?

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gtoformula
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Report this Post05-03-2014 11:38 PM Click Here to See the Profile for gtoformulaClick Here to Email gtoformulaSend a Private Message to gtoformulaEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by JamesCurtis:

I must say that your exhaust snugs up much better than mine does - nice work! I like the sound of the exhaust I have at idle and part throttle but it is a little loud going down the interstate. May I ask where you got the two 180* sections and what size of downpipe you used?



I drove it more this afternoon and found that the exhaust is a bit quieter at 70 mph cruising speed than I thought. I'll keep it like it is for now and hold off installing the resonator tips. To get the tight 180* bends I used the exhaust donuts that were recommended by revin. I found them on eBay for about $40. Cut it in half to get the 180* from the flex joint to the muffler and used another 90* section from the manifold flange to the inlet side of the flex joint. So the $40 bought two pieces. The entire system is 2 1/2".
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gtoformula
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Report this Post05-03-2014 11:42 PM Click Here to See the Profile for gtoformulaClick Here to Email gtoformulaSend a Private Message to gtoformulaEdit/Delete MessageReply w/QuoteDirect Link to This Post

gtoformula

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Member since Feb 2012
 
quote
Originally posted by JamesCurtis:

I must say that your exhaust snugs up much better than mine does - nice work! I like the sound of the exhaust I have at idle and part throttle but it is a little loud going down the interstate. May I ask where you got the two 180* sections and what size of downpipe you used?



James Curtis. You are one of the forum members that I failed to acknowledge. The pictures you posted of your system with the flex pipe was what made me install the same flex joint. Very glad that I put that into my system.
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Report this Post05-24-2014 02:30 AM Click Here to See the Profile for henrysscSend a Private Message to henrysscEdit/Delete MessageReply w/QuoteDirect Link to This Post
Am I seeing this right. Is their no converter on this? How do you get around the second O2 senser?
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Report this Post05-24-2014 02:17 PM Click Here to See the Profile for Lou6t4gtoClick Here to Email Lou6t4gtoSend a Private Message to Lou6t4gtoEdit/Delete MessageReply w/QuoteDirect Link to This Post
I have it somewhat Like Jamescurtis has, but I Used a 1995 Camaro muffler. (you would think if it quiets an LT1, it would quiet a 3800 ). Still not real quiet at all.
I think there May be a lot to the idea "it needs to take a longer route" before the muffler.
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gtoformula
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Report this Post05-24-2014 08:37 PM Click Here to See the Profile for gtoformulaClick Here to Email gtoformulaSend a Private Message to gtoformulaEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by henryssc:

Am I seeing this right. Is their no converter on this? How do you get around the second O2 senser?


Henry
No cat. Registered as an antique in Texas. Five year registration = $50 and no inspections. Regarding the second O2 sensor. Engine is from a 1998 Regal. I bought it with this engine and didn't do the install. Did Buick have a second O2 sensor after the cat? Runs great so no issues with wayward engine sensors.
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Report this Post05-24-2014 10:16 PM Click Here to See the Profile for MstangsBwareClick Here to Email MstangsBwareSend a Private Message to MstangsBwareEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by henryssc:

Am I seeing this right. Is their no converter on this? How do you get around the second O2 senser?


Second O2 is not used in the swap from the donor car to the Fiero. Its deleted off the harness and out of the PCM.
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Report this Post05-24-2014 10:20 PM Click Here to See the Profile for Neils88Click Here to Email Neils88Send a Private Message to Neils88Edit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by gtoformula:


Henry
No cat. Registered as an antique in Texas. Five year registration = $50 and no inspections. Regarding the second O2 sensor. Engine is from a 1998 Regal. I bought it with this engine and didn't do the install. Did Buick have a second O2 sensor after the cat? Runs great so no issues with wayward engine sensors.


That's interesting that you can register it as antique when it has a 1998 engine
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gtoformula
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Report this Post05-24-2014 10:59 PM Click Here to See the Profile for gtoformulaClick Here to Email gtoformulaSend a Private Message to gtoformulaEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by Neils88:


That's interesting that you can register it as antique when it has a 1998 engine


There is no inspection process in Texas to verify if an engine is original. No emissions inspection either. Just took the title to the tax office after I bought it and registered it as an antique. Not a DD so no issues of putting too many miles on.
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Report this Post05-25-2014 09:18 AM Click Here to See the Profile for revinSend a Private Message to revinEdit/Delete MessageReply w/QuoteDirect Link to This Post
The exhaust looks good. You could have adjusted it around a bit to "hide" it more, but good job!
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Report this Post05-25-2014 02:32 PM Click Here to See the Profile for Lou6t4gtoClick Here to Email Lou6t4gtoSend a Private Message to Lou6t4gtoEdit/Delete MessageReply w/QuoteDirect Link to This Post
"That's interesting that you can register it as antique when it has a 1998 engine ou6t4gto" Doesn't matter about the engine, only the VIN # .
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Report this Post05-27-2014 02:46 AM Click Here to See the Profile for PaulJKSend a Private Message to PaulJKEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by JamesCurtis:

... it is a little loud going down the interstate.



Mine has (2) california-grade cats and a 19" cadillac muffler. If I lift my foot off the throttle, all i can hear is the wind when going down the interstate .
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longjonsilver
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Report this Post12-07-2020 09:07 AM Click Here to See the Profile for longjonsilverClick Here to visit longjonsilver's HomePageClick Here to Email longjonsilverSend a Private Message to longjonsilverEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by nosrac:

You got the wrong magnaflow. The correct one is the transverse Camaro muffler.


Like this one???

https://www.magnaflow.com/p...-performance-muffler

jon

------------------
Astronomy says we will find a coded signal from outer space. Then we'll KNOW that life exists there, for coded signals aren't by chance.

Biology says there are coded genetic signals in every cell, but we KNOW that no intelligence created life.

I'm the original owner of a white ' 84 2M4 purchased Dec 10, 1983 from Pontiac. Always garaged, no rust, 4-wheel drifts are fun!

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