V8 exaust survey
03-02-2007, 02:03 PM
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V8 exaust survey
<center><img src="http://www.flowmastermufflers.com/products/images/cutaway_super40.jpg"></center><p>What exhaust modifications have people done?
I have, from the cats back, 2.25 pipes into a Flowmaster Super 40 dual in/out to plain tailpipes. It sounds great..except for the "flowmaster resonance" that can be annoying at low revs. One guy said it sounds like a big block, it definitely has a powerful sound to it. Nice and burbly, and much more distinctive than the glasspacks that most people use. Even Magnaflow mufflers are just shiny glass packs. I have plans to gut the cats if I can somehow get them off to work on.
I was thinking that perhaps a single 3" exhaust system would work well, and be more easily routed around under the car.
I have, from the cats back, 2.25 pipes into a Flowmaster Super 40 dual in/out to plain tailpipes. It sounds great..except for the "flowmaster resonance" that can be annoying at low revs. One guy said it sounds like a big block, it definitely has a powerful sound to it. Nice and burbly, and much more distinctive than the glasspacks that most people use. Even Magnaflow mufflers are just shiny glass packs. I have plans to gut the cats if I can somehow get them off to work on.
I was thinking that perhaps a single 3" exhaust system would work well, and be more easily routed around under the car.
03-02-2007, 07:40 PM
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Re: V8 exaust survey
"glass packs" are/is a term generally used in reference to a fibreglass packed tube, with a louvered tube running through it... ie, the old-school, uber low-tech straight in-out ~4" overall o.d. mufflers... "cherry bomb" is a popular brand...
Magnaflow don't use fibreglass packing (steel/ceramic, IIRC), the inner tube is perforated rather than louvered (having a far greater flow), and have a much larger volume of the sound-absorbing packing... giving them better sound absorbsion qualities then old-school(crappy) glasspacks.
a single 3" exhaust will be more restrictive than a dual 2.25" exhaust (assuming both are mandrel bent)
rather than gutting the cats (which is a huge no-no out here, dunno where you live), high-flow cats (catco/magnaflows are cheap enough) or "test pipes" would flow MUCH better... an empty/gutted cat is a flow nightmare, compared to something proper.
(sorry, dealt with hi-po auto and bike exhausts for years)
Magnaflow don't use fibreglass packing (steel/ceramic, IIRC), the inner tube is perforated rather than louvered (having a far greater flow), and have a much larger volume of the sound-absorbing packing... giving them better sound absorbsion qualities then old-school(crappy) glasspacks.
a single 3" exhaust will be more restrictive than a dual 2.25" exhaust (assuming both are mandrel bent)
rather than gutting the cats (which is a huge no-no out here, dunno where you live), high-flow cats (catco/magnaflows are cheap enough) or "test pipes" would flow MUCH better... an empty/gutted cat is a flow nightmare, compared to something proper.
(sorry, dealt with hi-po auto and bike exhausts for years)
03-02-2007, 07:52 PM
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Heres my 02..run for the hills ;-)
1st off, this is what a V8 should sound like.
http://www.motorgeek.com/phpBB2/gallery2.php/main.php?g2_itemId=30113
Some mild 5k revs.
But as far as the "crappy glasspacks" comment...I got glasspacks as mid mufflers on my new to me 91 v8 5spd! With straight pipes it sounds good. Not like my Stebro on my 90 v8..but fine.
I would concentrate on the exhaust header desighn 1st. The collector is tinny. The pipe desighn is good..but the collector should be larger cause the pipes meet at one place & all that gas is forced out a tinny hole. Thats your restriction, not the pipe size!
At that point it doesn't matter if the rest of the pipe is 2.5 or 3 inches.
When I put the new motor in my 5spd I'm going to mock up a true duel exhaust out eather side of the rear bumper.
http://www.motorgeek.com/phpBB2/gallery2.php/main.php?g2_itemId=30113
Some mild 5k revs.
But as far as the "crappy glasspacks" comment...I got glasspacks as mid mufflers on my new to me 91 v8 5spd! With straight pipes it sounds good. Not like my Stebro on my 90 v8..but fine.
I would concentrate on the exhaust header desighn 1st. The collector is tinny. The pipe desighn is good..but the collector should be larger cause the pipes meet at one place & all that gas is forced out a tinny hole. Thats your restriction, not the pipe size!
At that point it doesn't matter if the rest of the pipe is 2.5 or 3 inches.
When I put the new motor in my 5spd I'm going to mock up a true duel exhaust out eather side of the rear bumper.
03-02-2007, 09:21 PM
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not all "glasspacks" are equal... but don't get me wrong, i dig the sound...
i reckon i'm quite new around here, and admittedly to audis in general (when compared to other cars i have/had)... so it won't hurt me feelin's if i'm told to STFU, plus i don't wanna step on anyone's toes... 
good/bad examples...
good:
moroso spira-flow are considered a glasspack (despite the stainless packing), partially louvered (but well designed), with no measurable flow restriction... and sound awesome as a mid resonator/muffler when coupled with something along the lines of a magnaflow or ultraflo for the rear box. (sound good alone, just LOUD).
crappy:
cherry bombs are crap for flow restriction, the fibreglass/scrap packing is all but gone/burnt within a few months. "purple hornies" are the same. most any that the local chain parts store carries are along these lines.
my current exhaust... while not on a V8... not on an audi... not even on a n/a motor (a turbo does a great job of somewhat toning down the exhaust levels)...
3.5" downpipe, tapering to 3", 3" catco cat, no muffler, exit at rear bumper. 2.3L 8V 4cyl turbo motor... it's pretty quiet at idle/low revs, and very civil inside the car... HUGELY loud once the wastegate is open... and sorta sounds like a truck in-between (it's a volvo b230ft motor... they have that oddness to them). but i love the sound... and there's no real flow restriction.
the last exhaust i had on a somewhat comparable motor (4 litre bmw 32v V8), stock/well-flowing extractors/headers, dual catco 3" cats, x-pipe, dual 3" all the way to the rear box (dual 3" in/out magnaflow). flowed great, sounded mean (and pretty loud)... and a great improvement over the factory dual/single/dual ~2.25" exhaust with a removed mid resonator and gutted factory cats.
again, my experience (both personally and as a former fabricator, for whatever that's worth) is with lotsa cars OTHER than audis... so my opinion may not count for much, just sayin' it.
plus i can't talk cars/shop with the wife, she gets bored of it... so i'm left to forum discussions
good/bad examples...
good:
moroso spira-flow are considered a glasspack (despite the stainless packing), partially louvered (but well designed), with no measurable flow restriction... and sound awesome as a mid resonator/muffler when coupled with something along the lines of a magnaflow or ultraflo for the rear box. (sound good alone, just LOUD).
crappy:
cherry bombs are crap for flow restriction, the fibreglass/scrap packing is all but gone/burnt within a few months. "purple hornies" are the same. most any that the local chain parts store carries are along these lines.
my current exhaust... while not on a V8... not on an audi... not even on a n/a motor (a turbo does a great job of somewhat toning down the exhaust levels)...
3.5" downpipe, tapering to 3", 3" catco cat, no muffler, exit at rear bumper. 2.3L 8V 4cyl turbo motor... it's pretty quiet at idle/low revs, and very civil inside the car... HUGELY loud once the wastegate is open... and sorta sounds like a truck in-between (it's a volvo b230ft motor... they have that oddness to them). but i love the sound... and there's no real flow restriction.
the last exhaust i had on a somewhat comparable motor (4 litre bmw 32v V8), stock/well-flowing extractors/headers, dual catco 3" cats, x-pipe, dual 3" all the way to the rear box (dual 3" in/out magnaflow). flowed great, sounded mean (and pretty loud)... and a great improvement over the factory dual/single/dual ~2.25" exhaust with a removed mid resonator and gutted factory cats.
again, my experience (both personally and as a former fabricator, for whatever that's worth) is with lotsa cars OTHER than audis... so my opinion may not count for much, just sayin' it.
plus i can't talk cars/shop with the wife, she gets bored of it... so i'm left to forum discussions
03-03-2007, 04:21 AM
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BTDT isn't considered stepping on toes
Appreciate your thoughts on the subject.
& I was just busting a$$ on the glasspacks. I bought the car with them & know they aren't the best alternitive. I'll be ripping them out very soon.
& as far as the wife getting bored by car talk.....join the club! I talk to tons of Audi guys everyday & I've learned to go down stair to talk Audi. I start to talk about these cars & tossing ideas around & then that only leads to buying stuff.
I gotta seperate credit card for the wife when I buy Audi stuff. I call the card my "get off my back" card...he he
Thanx for your BTDT & look forward to hearing what you gotta say.
But please, please, please....don't ever put BMW & Audi in the same sentance :-)
BMW is my pet peev.
& I was just busting a$$ on the glasspacks. I bought the car with them & know they aren't the best alternitive. I'll be ripping them out very soon.
& as far as the wife getting bored by car talk.....join the club! I talk to tons of Audi guys everyday & I've learned to go down stair to talk Audi. I start to talk about these cars & tossing ideas around & then that only leads to buying stuff.
I gotta seperate credit card for the wife when I buy Audi stuff. I call the card my "get off my back" card...he he
Thanx for your BTDT & look forward to hearing what you gotta say.
But please, please, please....don't ever put BMW & Audi in the same sentance :-)
BMW is my pet peev.
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03-03-2007, 05:11 AM
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Re: V8 exaust survey
Can't speak for the V8's, but am looking at upgrading my 200 20V once i sell the other 200. Hopefully i'm not too far off topic!
Going to use a y, 2-1 then 3" out to the rear.
Leaning towards borla xr1 as a resonater, but may end up using a dynomax bullet muffler as pretty large $ difference. I would consider these a step up from glass packs as they are free flowing and definitly won't blow out in six months. Flowmaster also makes a resonater, but have used a lot of thier products and they only last a couple of years (of course i'm keeping this car FOREVER!)
Probably use a dynomax, flowmaster, something of the sort as a rear muffler. I already have one of each, so will have mounts made so they can be clamped on, muffler will be removable.
Figure i can swap stuff around to see what works/sounds appropriate
As for pipe size... Does the V8 "push" enough exhaust that flow through either dual 2ish" inch or single 3" will really make a difference? Talking a fairly small ci moter! For instance, my Z28 (stroker)has dual three inch exhaust. Heavily (no extremely)modified but the 3" duals are probably overkill. Sounds cool, looked awesome coming out the back, but probably unneccasary. Emits a different tone, but truthfully, HP gains are probably negligible (guess i could total up all the manufacturer claims, end up with a 900 HP car? Wishful thinking)
Realize the turbo is a different animal, but good exhaust is good exhaust!
Eric
Going to use a y, 2-1 then 3" out to the rear.
Leaning towards borla xr1 as a resonater, but may end up using a dynomax bullet muffler as pretty large $ difference. I would consider these a step up from glass packs as they are free flowing and definitly won't blow out in six months. Flowmaster also makes a resonater, but have used a lot of thier products and they only last a couple of years (of course i'm keeping this car FOREVER!)
Probably use a dynomax, flowmaster, something of the sort as a rear muffler. I already have one of each, so will have mounts made so they can be clamped on, muffler will be removable.
Figure i can swap stuff around to see what works/sounds appropriate
As for pipe size... Does the V8 "push" enough exhaust that flow through either dual 2ish" inch or single 3" will really make a difference? Talking a fairly small ci moter! For instance, my Z28 (stroker)has dual three inch exhaust. Heavily (no extremely)modified but the 3" duals are probably overkill. Sounds cool, looked awesome coming out the back, but probably unneccasary. Emits a different tone, but truthfully, HP gains are probably negligible (guess i could total up all the manufacturer claims, end up with a 900 HP car? Wishful thinking)
Realize the turbo is a different animal, but good exhaust is good exhaust!
Eric
03-03-2007, 04:18 PM
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whats wrong with bmw? As a generalized statement, Its hard to beat some of their cars...
The overall "goodness" of the 3-series is pretty much indisputable.
...And the M5/M6's performance... well... you know.
...And the M5/M6's performance... well... you know.