The Truth about Exhaust

[napkinthief]

I agree with this guy.

Looking at post one, performance is not his real goal. I wont venture a guess at what is, but I can guess it involves a certain noise.

This is true, performance is one of my goals, and the people on this site do help me get there. This is not a complete performance question so I threw it in the newbie forum to see what kind answers I would get. My other goals include keeping my car quiet when I get home at 2 am, and have some decent looks.

think about something for a sec. take a NA car or any car with a small exhaust pipe and a large tipped straight though muffler. they are LOUD and buzzy and gross. take then a turbo car, with a nice 3" exhaust, high flow cat maybe a resonator and an oval can straight through muffler. still loud, but not as bad by any means. and it sounds cool.

The stock n/a piping is 2.25 and the muffler is 2.5 not a big difference but sound is crap as hell. I will leave the exhaust as is until the turbo is in, and see how that changes things.

 

[staticbrainwash]

if performance and quiet is a goal. . . LISTEN TO ME. there are ways to get performance without being insane. i've said it twice already. 3"-3" high flow cat-3" resonator-3" oval can. it will be pretty quiet. and if you were really going for performance you didn't say that in the begining. you said "is big exhaust really worth the loudness". that says nothing about performance.

honestly, ANY exhaust can be loud if you get on it. but even with my 3" straight pipe with bullet muffler i don't wake up anyone in my VERY conservative neighberhood. just don't drive like an asshole and it wont be a problem. at most, when i just lightly city drive im no louder than most other cars. it's just a different tone.

i have now tried to help 3 times and you didn't pay attention, so i guess you can't care that much about "someone pointing you in the "right" direction", because i tried.

if you want performance you eventually have to sacrafice asthetics. deal.

im sorry if this sounds like im being a dick, but honestly, don't say no one is trying to help. because i was trying to help. and other people are too, you just never made it clear what you wanted out of the car/exhaust.

 

[BOOSTIN21]

i hope i am not lost here i just scanned through gritting my teeth.

have we asked what turbo are you running?
are you sure a N/A is only 2.25? my stock 1g was at 1.75

whether its aftermarket 2.5 or 3 it wont matter too much on noise. my buddy has a 1991 tsi awd b16g supporting mods and a buschur 3", very droney sounding but a beast at WOT. which i am sure you wont be at open throttle at 2am in your drive way.
i had a 3" ATR on my talon with ported 14b and i/c pipes. it was loud enough to set off car alarms at 50 ft away. my buddy had a 96 tsi awd with b16g 1g head and a thermal 3" with HRC downpipe. i could hear him from at least a half a mile and it was rattling pictures in my bedroom from a block away when he drove by.

pipe size wont matter too much its just bends, and muffler design. of course a 3" is TYPICALLY louder that a 2.5". if you want performance but dont want loud i would recommend a 2.5" exhaust from a exhaust shop/muffler shop. a high flow cat and a silenced muffler like APEXi.


thats just my .02 cents

 

[saiyansniper]

I'll be the extreme example on this one to solidfy the WOT issue.

Currently running a ported evo3 mani with a 16g, open o2. At a regular cruise and easing into the gas, not bad at all. Hell, can barely hear it. WOT sounds like all hell has broken loose and hurts your ears next to a freeway median/wall.

 

[staticbrainwash]

how does that help? he's talking about a full exhaust and you're talking about an open o2? where's the corrilation? unless you're trying to say that even with an open o2 it's not that bad. it's just a little weak.

and i agree with the 3" typically being louder, but 3" will also typically be much deeper toned than 2.5".

 

[tstkl]

if your worried about sound, the dejon tools exhaust is not for you, just fyi

 

[staticbrainwash]

hence why im not pushing the dejon. , i f-ing love mine though.

how do you like yours? or do you still not have it figured out?

 

[Scrubulum]

I don't think so. It has to do with cross sectional area I believe. pi*3^2 = 28.26 in^2 while 2*pi*1.5^2 = 14.13 in^2

Area is PI X R^2

Therefore: 2 X .75^2 X 3.14 = 3.532 in^2 and 1.5^2 X 3.14 = 7.065 in^2

The ratio is correct but the numbers are off. You would have to go with dual 2" to match a single 3"

The biggest problem with dual exuast on a four cylinder is that the head loss (read restriction) between the two sides is rarely the same. So you "never" have the same flow through both of the pipes. The gases are always going to prefer the path of least resistance. Then you become the guy in the winter that obviously only is "smoking on one pipe". I am not sure how cars like the SRT-4 or S2000 get away with it, although I have never watched them closely in cold weather. Dual exhaust is only an advantage when you can pull the split off at the head (read V6/V8) other then that it ends up looking silly.

 

[napkinthief]

if performance and quiet is a goal. . . LISTEN TO ME. there are ways to get performance without being insane. i've said it twice already. 3"-3" high flow cat-3" resonator-3" oval can. it will be pretty quiet. and if you were really going for performance you didn't say that in the begining. you said "is big exhaust really worth the loudness". that says nothing about performance.

honestly, ANY exhaust can be loud if you get on it. but even with my 3" straight pipe with bullet muffler i don't wake up anyone in my VERY conservative neighberhood. just don't drive like an asshole and it wont be a problem. at most, when i just lightly city drive im no louder than most other cars. it's just a different tone.

i have now tried to help 3 times and you didn't pay attention, so i guess you can't care that much about "someone pointing you in the "right" direction", because i tried.

if you want performance you eventually have to sacrafice asthetics. deal.

im sorry if this sounds like im being a dick, but honestly, don't say no one is trying to help. because i was trying to help. and other people are too, you just never made it clear what you wanted out of the car/exhaust.

Sorry if it seems like I am not listening to you, but I did read and take into account the information you gave. I think I am going to go with a 2.5 from the turbo back, cat, and fit as many resonators in there as I can. Will let you guys know about the final result when it gets done.

 

[napkinthief]

One question, I will be making my own custom piping, what size should the wall be, and does it have to be thicker at the downpipe or can I use the same size throughout? Approx how long a section of pipe would I need? I have a 2.5 bender and a welder so I just need a straight pipe.

 

[RockSolidGST]

When you add a turbo , it changes the sound completly from the exhaust ,its a much nicer tone.... By going turbo and making more restriction , your only minimizing your gains... Its as simple as that.... More air in , means you need more air out , Peroid.