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Old 04-06-2005, 04:11 PM   #1
SCGT
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Default Quieting the cobb intake

I know there was a thread about this a while back, but I wanted to discuss a new idea and see what the input was.

1) Get a flared port end, similar to what loudspeakers have (well, good ones, lol). On a speaker, a flared port makes the effective diamter surprisingly larger. This could only make it easier for the intake to pull in air. More power? I suppose maybe a fraction of a horsepower, but the big thing that I'm interested in is lowering the scream down, a larger diameter pipe will resonate at a lower frequency. Thoughts?

2) Cover the outside of the intake (except the plastic section where the filter is) with dynamat. This will further reduce any airborne resonations.



I tried the egg-crate foam in the fender trick and didn't really notice anything. Any thoughts?


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Old 04-06-2005, 04:21 PM   #2
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get an exhaust... then you wont notice it as much.
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Old 04-06-2005, 04:52 PM   #3
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Someone lined the hole in the fender where it goes with foam (Aquacow?) and it became much quieter, supposedly.
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Old 04-06-2005, 10:17 PM   #4
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Yes, line the inside of the fender with dynamat and and put koozies over the intake.
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Old 04-06-2005, 11:39 PM   #5
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I got a question regarding COBB intake, is it really that loud that you need to reduce the noise of the intake???
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Old 04-06-2005, 11:41 PM   #6
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no. i loved teh sound.. i guess it depends on the individual.
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Old 04-07-2005, 03:31 AM   #7
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The intake is hardly noticeable noise wise unless you're near to or at WOT and above 3500rpm. You can hear the difference at lower revs and not at WOT, but its only different, not loud. But yes, once you hit 3500 or so at WOT it is loud, but I haven't heard any negative comments on it from any of my friends, including the hippies
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Old 04-07-2005, 03:57 AM   #8
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for my noobness and stupidity, what is WOT? LoL...

So once i reaches 3500rpm, it starts to scream at you???
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Old 04-07-2005, 04:02 AM   #9
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Wide open throttle

Exactly what does your guys Cobb intake sound like?

Mine sounds like a low pitch hum at idle....weird.
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Old 04-07-2005, 11:31 AM   #10
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yeah why would you want to silence it? like everyone said it's not that loud under 3k rpm and partial throttle.

side note: i was going through some papers and came across the install instructions for the cob cai. with the pre 03 no IAT intakes there are three hoses that come off the primary, one that mates at a t-joint w/ the pcv valve hose. what purpose does this serve? maybe a noob ?, but does anyone know?
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Old 04-07-2005, 11:33 AM   #11
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I don't really notice mine at idle, but it is definately a lower deeper pitch once I start giving it gas. Sounds good . There is also a very slight whistle thats hardly noticeable at partial throttle around 2000 or 2500 I think.
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Old 04-07-2005, 12:10 PM   #12
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again, why make it quieter????? You spent all that money on an intake that does a great job at adding power and torque and now you want to possibly reduce it to make it quieter?

dribble, i just installed my friends intake on an 02 the other night. I the nice thing about the 02 setup is you dont have to even touch the sensor. you just run to the hose in the front of the airbox, and the two nipples. On my 04, i had to get some slack out of the wires taped together a million times to get my sensor to stretch. Dont know if that answers your question.
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Old 04-07-2005, 01:46 PM   #13
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The flared port idea is interesting. It would be the complete opposite of a loudspeaker's port function (taking in air rather than blowing it out) but I wonder if it could smooth out the sound a bit?

Then you could take it a step further and dimple it's surface like B&W does to avoid "chuffing" as they call it.

I can't wait to get my Cobb Intake.

Bill
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Old 04-07-2005, 02:19 PM   #14
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it sounds really awesome when you go through a tunnel..
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Old 04-07-2005, 04:16 PM   #15
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My intake is drowned out by the exhaust until around 5000rpm where it honks pretty loudly.

I don't plan on quieting it down, I like how it sounds
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Old 04-07-2005, 04:55 PM   #16
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Quote:
Originally Posted by jeisen
again, why make it quieter????? You spent all that money on an intake that does a great job at adding power and torque and now you want to possibly reduce it to make it quieter?

dribble, i just installed my friends intake on an 02 the other night. I the nice thing about the 02 setup is you dont have to even touch the sensor. you just run to the hose in the front of the airbox, and the two nipples. On my 04, i had to get some slack out of the wires taped together a million times to get my sensor to stretch. Dont know if that answers your question.


Adding a flared port and dynamat to the outside of the intake won't reduce power. I fail to see where you're coming from, it's not like I was planning on puttnig a restrictor plate on the dang thing. A flared end would make it EASIER for the intake to take in MORE air. Insulation on the outside of the aluminum tube would not subtract anything either.

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Old 04-07-2005, 04:59 PM   #17
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Quote:
Originally Posted by wgb113
The flared port idea is interesting. It would be the complete opposite of a loudspeaker's port function (taking in air rather than blowing it out) but I wonder if it could smooth out the sound a bit?

Then you could take it a step further and dimple it's surface like B&W does to avoid "chuffing" as they call it.

I can't wait to get my Cobb Intake.

Bill

Well, it wouldn't be the complete opposite of the loudspeaker port function. Audio design is something I do (before I get started).

B&W have made a very significant design flaw with their dimpled port. That is, air in a loudspeaker port is alternating in direction, the same a woofer cone. The dimples only work if the air flow is one way -as with a golf ball. The dimples cause all sorts of problems when the air changes direction, but it's a pretty easy to market design, and people fall for it hook line and sinker. I have some technical papers showing how it doesn't work as advertised, if you're interested PM me.

Anyway, I was thinking it could help, and reduce the resonating frequency while smoothing out airflow. I have an idea on how much air needs to go through, so coming up with a flare radius isn't going to be a problem. I probably wouldn't do the dimple trick though because it'd be so much of a pain to do by hand.


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Old 04-07-2005, 05:13 PM   #18
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Quote:
Originally Posted by jeisen
dribble, i just installed my friends intake on an 02 the other night. I the nice thing about the 02 setup is you dont have to even touch the sensor. you just run to the hose in the front of the airbox, and the two nipples. On my 04, i had to get some slack out of the wires taped together a million times to get my sensor to stretch. Dont know if that answers your question.
i had the same problems with the wire bundle. the question i was asking was about the instructions showing a third hose mating to the pcv valve w/ a t joint. i was wondering why it was necessary in those models, basically why 3 hoses and why join at the pcv valve?
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Old 04-07-2005, 05:53 PM   #19
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Why would you want to quiet the COBB CAI? I'll tell you why - I was pulled over for a suspected damaged or missing exhaust system! YES, IT'S THAT LOUD!

My experiment thus far has involved coating the aluminum tubing with B-Quiet's Brown Bread, followed by a coat of their H-Liner. The Brown Bread is akin to Dynamat, and the H-Liner is like 1/4 inch of foam covered with foil. It removed some of the raspiness, and probably keeps some of the heat away from the tubing, but it wasn't enough to kill the roar.

I did turn the first elbow from the fender toward the stock intake scoop (in the front, over the grille - that thing), and the noise was gone, or at least removed enough that I didn't notice it in the car. With apologies to our audio man, I'm not putting any money on the idea that a bell opening will help enough to say so. Intake pulses blasting the fender are the problem, and only redirection or dampening are going to make the difference.

Does it sound "cool"? Yeh, but only when you really want to hear it. Passengers hear it. Police hear it. The neighbors hear it.

This is my best guess, and progress so far.
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Old 04-07-2005, 08:54 PM   #20
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LetitSnow:

Congrats on a well thought out project. Your head is in the right place, it's nice to see some thinking about this. yes, the cobb sounds good, but it can be FREAKIN' LOUD.

Could you give more details about how you changed the elbow piece?


Thank you,

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Old 04-07-2005, 10:10 PM   #21
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Sounds like he just rotated it in the clamp on the filter section.
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Old 04-07-2005, 10:14 PM   #22
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Exactly... I put the opening of the short elbow (normally in the fender) onto the scoopy stock intake thing, just by turning it. I leave the scoop on there cos I put the stock intake back when I visit the service department.

I'll post pics and progress as it happens.
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Old 04-07-2005, 10:24 PM   #23
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edit: deleted content for scgt

Last edited by isburns; 04-08-2005 at 03:52 AM.
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Old 04-08-2005, 02:00 AM   #24
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Quote:
Originally Posted by isburns
Do you really drive your car WOT that much in areas where it would bother the people you mentioned? I guess I'm just softer on the gas pedal when or if I'm worried about what other people think. My reasoning is if I'm worried about what neighbors or passengers think of the sound, I probably shouldn't be driving hard enough for them to hear it.

Basically with neighbors, I don't got WOT or drive fast enough period near my house for it to be a problem because there are a lot of kids that ride their bikes in the street and dogs that can jump right out in front of my car. Once I got the Cobb intake, I had another reason not to go WOT because of the noise.

With passengers, if I'm worried about what they think of the sound of my car, I figure they probably don't want to ride with me when I'm driving hard anyway, so I just avoid it with certain friends. On the other hand, my friends that don't mind me driving hard and who drive their cars hard themselves don't mind the sound of my intake.

With cops, maybe I'm lucky in Arizona that they don't seem to care very much.

That's great but not really relevant to the question asked.


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Old 04-08-2005, 03:51 AM   #25
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true... guess I'm just as bad as everyone else on here...
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