Custom exhaust - exhaust note question

AlfaBeta
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Custom exhaust - exhaust note question

Post by AlfaBeta » Mon Dec 25, 2006 7:05 am

Hi Gang,

I have an 88 Milano verde (3.0L). I realize it's not a gtv6 but it shares a lot of the same equipment so I was hoping someone from this list could help. I completely changed the exhaust system (I'll give details in a minute), thr car burbles nicely at idle and sounds great on acceleration. However at harder acceleration and at semi higher rpm (4000-4500 rpm maybe) there is a terrible "metallic sounding resonance" that comes from the tailpipe. It almost sounds like a Honda Civic. Anyway, I'll list below what I did but if anyone has any ideas as to what is causing this or what I can do to limit it please let me know!

*CSC headers
*Each downtube is mated to an open flow Random Technologies catalytic converter
*The catalytic converters then exit to a Y tube
*The Y tube then exits to a 2.5" exhaust pipe with no center muffler
*Magnaflow muffler at rear. This is the open flow type with a perforated tube. The tube has a slight S bend in it so the outlet matches up with the stock bumper cutout

Thanks

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Post by Sporttunergtv6 » Mon Dec 25, 2006 9:08 pm

I run a similar setup:
CSC headers
2.5 magnaflow y
into a flowmaster single chamber 40 series muffler
and exiting the passenger side of the car infront of the dedion cross member.
it sounds just the way you characterize it (lots of resonance beneath 3k and from there on she is a screaming italian whore!)
the only way to tune the sound is to use a bigger muffler, and/or smaller tubing.
vittorio
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Post by AlfaBeta » Sat Dec 30, 2006 6:49 am

Hi Sporttunnergtv6:

Thank you for the reply.

AB
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dan668s
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Post by dan668s » Sat Dec 30, 2006 12:34 pm

Hi,

I had the same problem with resonance when I replaced my center-muffler with a straight through pipe. This was on my previous GTV6, I bougth some cheap mufflers and got the welded in where the straight through section used to be, and the problem was solved.

I didn't have any performance headers or performance rear-section at the time, but a lot of GTV6 owners have had resonance-problems when only using a straight through pipe as center-section...

On my current GTV6 I'm running CSC headers, no cats, CSC middle section and a Stebro rear-section and the sound is great!!

Hope this helps....
Alfa Romeo - The thinking man's car!
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2004 Alfa Romeo Sportwagon 1.9 JTD
1986 Alfa Romeo GTV6 2.5
Rotundus
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Post by Rotundus » Fri Apr 06, 2007 12:16 am

stock heads
stebro straight pipes
stebro middle
stebro rear

she sounds like this... she was loud as fuck!

http://www.ozan.ca/ozansgtv6sound.mp3
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Post by powderhoundcd » Fri Apr 06, 2007 12:10 pm

I'm running:
stock headers
custom built y fromt 2" to 2.5"
Cherry Bomb (cheapest I could find) glasspack
Flowmaster 40 series muffler
out the back

The sound is really nice, but the flowmaster gives some loud resonances at certain RPM's. I had some of that metalic resonance that you describe before I stuck the glassback in there, but now it sounds absolutely amazing under full acceleration.

Carson
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83 GTV-6 2.5L (in progress)
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Post by GarthW » Fri Apr 13, 2007 6:48 am

Quite bizarre why it would make that niose, but then again there would be a logical explanation to it i suppose. :roll:

When i changed muffler, i replaced with an Apexi stainless with pipe straight out and sound is great, but badly miss my old ansa muffler :cry:
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Post by Steve R » Wed Jun 27, 2007 11:58 am

Hi all, I haven't been on the forum for ages, good to see the regulars are still on line and keeping our Alfa's front and centre!

Thought I'd chip in on this thread as I made a custom side exit exhaust for my GTV6 a couple of months back. CSC manifolds, twin 2" pipes into a single straight thru box that merges to 1x 2.5", then out to the left handside via a very wide flat part for ground clearance, and out via a slightly upswept 2.5 pipe. burbles OK on tickover, acceptably quiet when cruising, but F***ING loud when you want it to be!

Drove to Le Mans the other weekend with a group of friends for the race (which was FANTASTIC!) and one of my mates took a couple of video clips of my GTV6 on his phone, I've converted them to MP3 for your approval.

One thru a French tunnel from my mates mini following behind, the other in car joining a dual carriageway....

Gotta LOVE the sound of an Alfa V6

Enjoy ! :D
Attachments
GTV6 sound run.mp3
Joining a dual carriageway
(943.13 KiB) Downloaded 771 times
GTV6 tunnel 1.mp3
Through a tunnel from the car behind
(1.14 MiB) Downloaded 966 times
Two snowmen in a garden, one says to the other, "Can you smell carrots?".
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PietereQ
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Post by PietereQ » Tue Jul 10, 2007 11:53 am

That's a thread i wanted to start. :)
I also have exhaust note problem, yet of more aesthetic nature. I just don't like the way my exhaust sounds. While it is barely fair inside:
http://pl.youtube.com/watch?v=Lgn0sJa3Bvs
It's absolute crap outside:
http://pl.youtube.com/watch?v=iQPrUfwGecg

To much bass and disturbance in the most of the whole sound spectrum.
Im looking for this, beautiful, screaming tenor, just the one Steve R presented. My exhaust layout is; stock headers europipes, and all the way to center muffler, and to straight rear free flow muffler (which has barely greater diamater than the ehxaust tip. Can i alter the sound just by playing with the rear muffler or i have to plan entire exhaust from the scratch?
Thanks,
Pete
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Zamani
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Post by Zamani » Tue Jul 10, 2007 12:08 pm

Try just the rear. Get straight through muffler with 2 X 1.75" outlet pipes. Smaller pipes will tend to make the pitch higher.
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PietereQ
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Post by PietereQ » Wed Jul 11, 2007 11:17 am

Thanks for the tip Zamani. Well two tips are what I'm afraid of - this will mean cutting my rear zender bumper :cry:
I was initially thinking, to replace, my proxy rear muffler with magnaflow, that would be almost bolt - on in my current situation:
Image
But i'm afraid it won't help her to sing she is meant to be... Wha do you think? Or should I start looking for ansa, stebro, and a saw...
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Post by Zamani » Wed Jul 11, 2007 1:56 pm

Make the pipes snake down below the rear valance. Don't have to cut it. Just ask a good exhaust shop to custom bend the rear pipes so it goes under the valance.
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Post by PietereQ » Mon Jul 16, 2007 1:04 pm

Thanks Zamani ill give it a try then :)
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Re: Custom exhaust - exhaust note question

Post by sfyamr1 » Sun Jul 22, 2007 10:03 am

Yeah, I have a "Frankenstein" exhaust too. It starts like yours, with the awesome CSC headers, then to twin generic hi-flow bottle cats, to an ANSA straight through mid, and a Stebro rear. It runs like mad up top, bit it's too "tinny" and loud. I'm just going to order the Stebro cat/mid. Perfect mix of performance and sound, IMHO.
AlfaBeta wrote:Hi Gang,

I have an 88 Milano verde (3.0L). I realize it's not a gtv6 but it shares a lot of the same equipment so I was hoping someone from this list could help. I completely changed the exhaust system (I'll give details in a minute), thr car burbles nicely at idle and sounds great on acceleration. However at harder acceleration and at semi higher rpm (4000-4500 rpm maybe) there is a terrible "metallic sounding resonance" that comes from the tailpipe. It almost sounds like a Honda Civic. Anyway, I'll list below what I did but if anyone has any ideas as to what is causing this or what I can do to limit it please let me know!

*CSC headers
*Each downtube is mated to an open flow Random Technologies catalytic converter
*The catalytic converters then exit to a Y tube
*The Y tube then exits to a 2.5" exhaust pipe with no center muffler
*Magnaflow muffler at rear. This is the open flow type with a perforated tube. The tube has a slight S bend in it so the outlet matches up with the stock bumper cutout

Thanks

AlfaBeta
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Post by GTV27 » Wed Sep 05, 2007 11:38 pm

mine's fairly tame, a 2 inch stainless system with a straight-through resonator in the middle and a centre chamber muffler at the back. It is very quiet unless you wring its neck, and even then, its mostly engine noise.

However, as I use it on the track this is just not acceptable - it is virtually silent compared to the other cars.

So I've had a new rear section made up that I can swap the muffler out for at the race track - about 50 cm of straight pipe.

Fitted it up last night and took the car for a spin...holy f@#$! :shock:

At idle it sounds deep and bassy - more like a 5 litre engine!

Up about 3000, its loud, but not completely over the top.

Over 3000 it begins to develop a howl. As it climbs onto the cam, it shreiks like a banshee, all the way out to the limiter at 6,5.

When you back off, it pops and bangs and splutters.

My only problem is I don't want to put the road exhaust back on! :twisted: Can't wait until the next track outing!

Now, apart from sharing the enthusiasm with like minded individuals , I wanted to seek a view on the performance benefits.

It FEELS like it has more torque and power, particularly reving more freely from 4000 onwards.

I have no data to support this and it could just be psychological. :oops:

Anybody else had a similar experience going from a baffled to unbaffled exhaust.
Jason
1983 GTV6 2.8 litre
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