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Old 06-07-2005, 01:06 AM   #1
King Fish
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Default Funny part on intake.


(Photo from Dave on rs25.com)
what if i take that "?" shaped thing off and cover the hole up ... would it effect anything?
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Old 06-07-2005, 03:20 AM   #2
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it'd be way easier if you just replace the whole pipe. I tried to take off that piece, but it seems to be melted on or something.
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Old 06-07-2005, 03:36 AM   #3
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Pardon my stupidity, but what intake is that? I'm curious about that air box. And what MY is that impreza? Interesting.
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Old 06-07-2005, 03:52 AM   #4
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My2005
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Old 06-07-2005, 09:18 AM   #5
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I didn't laugh
Anyway, it's either there to add volume to your intake air chamber, or to reduce resonance. Either way I doubt you'd gain anything by removing it.
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Old 06-07-2005, 10:34 AM   #6
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well im just wondering cause i took it off and now i have a CEL on just wondering if that could have caused it ... and in the picture it is a 05 and Dave from rs25.com took the airbox out and repalced it with a ram air tube and filter. the link is here if you want to check it out Link the Dave's intake
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Old 06-07-2005, 01:55 PM   #7
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did subaru engineers team up with Larry to make this "ganzflow" setup? jk
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Old 06-07-2005, 02:04 PM   #8
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yeah I have one of those curly q thingies on my old neon. I took it off no problem, but the neon was a MAP car, not MAF, so who knows with the RS?
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Old 06-07-2005, 03:42 PM   #9
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The part in question appears to come after that sensor, so it seems logical that you might get a CEL, especially if you have a leak.
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Old 06-07-2005, 04:06 PM   #10
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it is there to help eliminate resonant frequencies from making the maf read incorrectly. put it back on. it will not give you magical horsepower by removing it.
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Old 06-07-2005, 04:58 PM   #11
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hmm alright i took it off to see if it would do anything ... guess its time to get the magical Injen intake cause i dont have the "?" part any more
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Old 06-08-2005, 01:39 PM   #12
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I may be wrong but it believe helps with low-end. It basically keeps a small amount of reserve air to be used when you first shift into gear. As you depress the gas it sucks this air first then from the filter.
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Old 06-08-2005, 02:24 PM   #13
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Quote:
Originally Posted by Nipper77
I may be wrong but it believe helps with low-end. It basically keeps a small amount of reserve air to be used when you first shift into gear. As you depress the gas it sucks this air first then from the filter.
No.

As already posted, it's there to muffle the resonance in the intake.
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Old 06-09-2005, 12:26 AM   #14
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Quote:
Originally Posted by Hawk296
No.

As already posted, it's there to muffle the resonance in the intake.
i think the shape and placement gave it away. it is an interesting peice tho. but what is the plastic dome/box rleading into the intake manifold? and y do cai remove it?
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Old 06-09-2005, 02:16 AM   #15
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Quote:
Originally Posted by assassin_2.5
i think the shape and placement gave it away. it is an interesting peice tho. but what is the plastic dome/box rleading into the intake manifold? and y do cai remove it?
Are you talking about the 2nd airbox up on top? THat 2nd airbox is the thing that supposedly helps with low end torque by creating a resevoir of air. To be honest I really don't know what the new 05s and such are like. It seems like they have gone several different versions of the intake over the years.

Last edited by Hawk296; 06-09-2005 at 02:21 AM.
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Old 06-09-2005, 02:28 AM   #16
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that thing is a silencer quiets the intake down
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Old 06-09-2005, 03:40 AM   #17
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yeah, the poster above sounded pretty darn confident about the piece being there to keep the maf reading correctly, but I was always told those pieces were there to help muffle the intake sound. I could see reasons why it MIGHT do either or both... My 2001 is running without those extra pieces and never threw a cel. Are you sure you didn't do something else that threw it?!?
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Old 06-09-2005, 05:14 AM   #18
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yea you must have something else wrong those wouldnt make you throw a CEL
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Old 06-09-2005, 09:09 AM   #19
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Quote:
Originally Posted by assassin_2.5
i think the shape and placement gave it away. it is an interesting peice tho. but what is the plastic dome/box rleading into the intake manifold? and y do cai remove it?
the "plenum box" or 2nd air box, is there for high rpm power. the higher the rpms, the more air is needed. Most cars have a larger intake plenum (big log before the intake runners) but our intake manifold has a tiny fist sized plenum. at high rpm's, without the plenum box, the engine will not get enough air, and will get sporadic amounts of air into each cylinder. having a reserve of air in the intake path will reduce that problem. since alot of EJ series motors are turbo'ed, they stuck with the same manifold design, and added the plenum box to work with N/A use.
removing that plenum box on MAF equipped cars is a bad idea. since the box is after the maf, incorrect readings at high rpm's will result, causing a lean-run situation, and possible damage will occur.
MAP cars are not affected, as the map sensor is on the intake manifold, downstream of the cold-air-intake.
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Old 06-09-2005, 02:51 PM   #20
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Quote:
Originally Posted by 99subi
yea you must have something else wrong those wouldnt make you throw a CEL

it ended up being that my air filter was very dirty ( it was not brown but black with grease dirt and oils ) changed that and now it is fine
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Old 06-09-2005, 03:21 PM   #21
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Its a Helmholtz resonator.

http://www.mecc.unipd.it/~cos/DINAMO...suonatore.html

A tube with d diameter and L length with resonate at a specific frequency with varying intensity relative to the speed of the air traveling through it. This phenomonon is known (other than resonance) as an Aeolian Harp. See also the Tacoma Narrow bridge.

The resonator dampens this sound in the intake at the resonance of the tube diameter and length. It is essentially an air spring that attunates the waves produced, that can wreak havoc with flow inside of the tube under the right circumstances.

Weather or not you can actually reach the right (wrong) circumstances to generate flow problems is debateable, and the addition of a high flow air filter introduces more intake engine noise into the intake which is likely beyond the attuneating ability of the resonator anyway.

It is going to have very very little effect on the flow of the air through the tube weather it is there or not. Leave it alone until you remove the entire intake as the likely hoood of making flow worse by messing around with the interfacing area between the two parts is pretty good. Aside from that, it is possible that it reduces some dips in the output of your engine. If you aren't replacing your intake, screwing around with the stock intake by cutting off pieces isn't going to improve flow.
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Old 06-09-2005, 03:22 PM   #22
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Quote:
Originally Posted by Boost-Free Subee
the "plenum box" or 2nd air box, is there for high rpm power. the higher the rpms, the more air is needed. Most cars have a larger intake plenum (big log before the intake runners) but our intake manifold has a tiny fist sized plenum. at high rpm's, without the plenum box, the engine will not get enough air, and will get sporadic amounts of air into each cylinder. having a reserve of air in the intake path will reduce that problem. since alot of EJ series motors are turbo'ed, they stuck with the same manifold design, and added the plenum box to work with N/A use.
removing that plenum box on MAF equipped cars is a bad idea. since the box is after the maf, incorrect readings at high rpm's will result, causing a lean-run situation, and possible damage will occur.
MAP cars are not affected, as the map sensor is on the intake manifold, downstream of the cold-air-intake.

Now I could be wrong but that is hard plastic and if yur trying to suck air out of the under load you would crush it because there would be no way air could get back in.
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Old 06-09-2005, 04:18 PM   #23
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Quote:
Originally Posted by holland_patrick
Now I could be wrong but that is hard plastic and if yur trying to suck air out of the under load you would crush it because there would be no way air could get back in.
air is gasous, and is therfor compressable. THis is the property which (among many other things) allos your engine to be throttled with a throttle plate. You don't control your car with the "gas" petal. It has nothing to so with the fuel, you are controlling the ammount of vacuum in the manifold. THe more vacuum (less movement of teh throttle petal) you have higher vacuum and therfore less dense charge of air entering your cylinder. Less dense air contains less oxygen molecules, and has a less powerful explosion when it is ignited with the proper ammount of fuel.

Why do you tink that you gain power with a free flowing filter or no filter at all? You have less vacuum in the intake tract, and a denser charge making it into the engine.

When you hit the throttle hard under acceleration, the manifold is emptied and the vacuum wave travels up the intake until air is accelerated (it has mass, so it doesn't immediatly start moving, not is it like a chain where you pull the end of it, the end moves just as far. You move one end and a vacuum is formed in the intake, if you evacuate enough of the air and creat a big enough vacuum your car will stumble. THe plenum on the intake acts like a buffer to store an ammount of air so that it doesn't occure.
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Old 06-09-2005, 06:53 PM   #24
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but the injen cai for the 2005 rs removes the intake plenum, is that remedied by the hi flow filter b/c the hp on that cai is made all at the top end.
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Old 06-09-2005, 08:03 PM   #25
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The tube is not restrictive, and the volume of the tube, from the throttle body to the filter is generally enough. Extremely short intake J tubes will more often than not exibit a tendency to hesitate.

"low end" and "when you hit the throttle" are not the same thing. "when you hit the gas" would be a transient throttle circumstance (drastically changing the velocity of the air in the intake, slow to fast, with very high acceleration), going from low throttle to full throttle. Low end would be a steady state throttle, wide open, at lower revs as it gins RPMs (the air accelerating slowly as the engine gains RPMs, don't confuse velocity with acceleration).
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