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Discussion Starter #41
They don't, you don't need one in the factory set up because the box holds the filter in place on both ends. I put a hose clamp on mine when I took my entire airbox off to run it like a ram intake. Shouldn't have any issues with the lid off either because the box still supports it and holds it in place.
I'll throw a hose clamp on it and try it without the lid that way.

I'm amazed at how great these little 2.0's sound. I mean both the intake noise and exhaust.
 

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I'll throw a hose clamp on it and try it without the lid that way.

I'm amazed at how great these little 2.0's sound. I mean both the intake noise and exhaust.
The bottom lid has small metel flippy pieces that help hold the filter in place. At least on mine it does.

Agreed. These are the best sounding 2.0's I have ever heard.
 

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On a side note, I found a way to run an open lid with possible benifits; although not very practical for daily driving, and not 100% "safe."

If you close the hood until the safety latch locks (not all the way closed), you have an opening to get direct cold air to the opened lid filter. Also by doing this, it leaves a gap at the back of the hood (which is normally sealed)- that may create a "cowl induction" effect by sucking the hot air out from under the hood.

Again, not very practical, but it should be a good way to avoid heat soak.

EDIT: probably not legal, and done at your own risk lol
 

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Yeah that's risky. lol

Also, cowl induction hoods suck air in at the back.
So the air coming in the front might fight against that. Not sure.
 

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Discussion Starter #45
Sorry I haven't been as active lately fellas. Work has been killing me.

Just a quick update for those that are curious; I've ordered a replacement intake resonator. I've also ordered an airbox lid to modify for intake noise.
 

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On a side note, I found a way to run an open lid with possible benifits; although not very practical for daily driving, and not 100% "safe."

If you close the hood until the safety latch locks (not all the way closed), you have an opening to get direct cold air to the opened lid filter. Also by doing this, it leaves a gap at the back of the hood (which is normally sealed)- that may create a "cowl induction" effect by sucking the hot air out from under the hood.

Again, not very practical, but it should be a good way to avoid heat soak.

EDIT: probably not legal, and done at your own risk lol
Ahaha, there was a video that came out last week of someone with a brand new civic and the hood wasn't latched closed while filming.
They had to get a new windshield
 

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If you guys want a nice mod, simply remove the airbox resonator and replace the lower airbox piece by this part number: CV6Z-9A612-A
It's basically the same lower airbox piece but without the hole.
 

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If you guys want a nice mod, simply remove the airbox resonator and replace the lower airbox piece by this part number: CV6Z-9A612-A
It's basically the same lower airbox piece but without the hole.
[thumb] This is the first I've seen this recommendation. I see this is used on several applications, including the ST. Is this a direct swap for the Mk3? Does it fit the mount points and cold air feed tubes in the Focus exactly, or are modifications required? Is seems like it should since it has a Focus application, but I just want to clarify.
 

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By the way, I know everyone talks about how it will suck in hot air, and I'm sure it does.. but honestly according to my butt dyno (which can be a big fat liar sometimes) I noticed no decrease in performance, off the line or not.
FWIW, I have an open-ended filter with a plug (K&N). The engine does seem to lose some power in the summer with the cap off, but our summers are a lot more brutal down here ;) I imagine you won't have as much a problem in the hills of West Virginia, but I just push the cap in when average highs get above 85 or so.
 

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Ahaha, there was a video that came out last week of someone with a brand new civic and the hood wasn't latched closed while filming.
They had to get a new windshield
Back in my carshow days....a buddy i was with at hot import nights, he went to his car
to move it to the other side of the stadium....took off hot and we hear a bang!!! See his hood flying in the air....landed between two cars....windshield shattered....some piece of.shit removed his hood pins....he had a carbon fibre hood laid on a metal frame, but obviously not
as safe as an oem.hood. He got locking hood.pins pretty quick.after that.
 

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Back in my carshow days....a buddy i was with at hot import nights, he went to his car
to move it to the other side of the stadium....took off hot and we hear a bang!!! See his hood flying in the air....landed between two cars....windshield shattered....some piece of.shit removed his hood pins....he had a carbon fibre hood laid on a metal frame, but obviously not
as safe as an oem.hood. He got locking hood.pins pretty quick.after that.
What is it with people stealing hood pins? I mean seriously... Someone stole hood pins off my 71 Vega too. Is it a gear head crack addict thing? I swear it's an equivalent to meth addicts stealing copper piping.
 

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What is it with people stealing hood pins? I mean seriously... Someone stole hood pins off my 71 Vega too. Is it a gear head crack addict thing? I swear it's an equivalent to meth addicts stealing copper piping.
People will steal anything not locked...and that only keeps lazy thieves away.
 

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I know it's not socially acceptable to revive old threads, but can somebody help me understand what the air box resonator is? I understand the purpose is to reduce noise, but is there any other function? I'm looking at the part (BV6Z-9B659-A) right now - is it literally just a closed, empty chamber that's sealed off at the air box or is there another opening for airflow? Because that's what it looks like, but that seems too unnecessary to believe. [???:)]

I'm asking because I noticed the foam seal at tube that connects to the bottom of the air box has deteriorated quite a bit on my car, so now the seal is less than perfect. I'm wondering if I should replace the part or just plug the hole, but I want to understand how the airflow would be affected. I don't care about sound.
 

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Hi gang.

My ingenious self filled the airbox resonator with Great Stuff. My idea was to gain a little more intake noise and reduce airbox turbulence. Chalupa Jones asked me if I used a high heat foam. I checked the can (after the fact, of course) and it says not to use around anything higher than 240 degrees. Unsure of exactly how warm the engine bay can get, I removed my now Great Stuff filled airbox resonator.

My problem: Now at 3,100 RPM I get a hugely loud and headache inducing drone.

What I need: Is a solution. I'm unsure of exactly what I can use in the engine bay because of the heat. In the mean time I'm going to attempt to remove the Great Stuff from the airbox resonator and re-install that.

Yes, I know I'm an idiot. Thanks in advance for any help.

I used gorilla tape to cover the hole where the resonator attached to the air box on the bottom. I did it real nice like and a couple of layers. It never melted or caused any issues.

I ran with it like this for at least a year or more, until I put the RS Airbox on which has no resonator or hole in the bottom.
 

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Intake air resonation can be easily affected by a simple closed end box as it changes the resonating frequency of the intake stream. There are sonic waves there just like in an exhaust muffler and they if getting timed right greatly increase noise if the setup is messed with. You have air going into engine but some of it backs out to come back out the intake at certain rpm when the lengths and displacement of the intake tract line up wrong to do it. They often correct by adding airbox volume (empty dead-end box to make you go ????, it is a wave strength absorber) to alter the resonation frequency of the tract and it stops much noise. As well, the resonation control method can add a decent chunk of very low rpm torque as the resonation at lower speeds can mess with the injection in intake ports to create backflow that affects off idle performance.
 

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Intake air resonation can be easily affected by a simple closed end box as it changes the resonating frequency of the intake stream. There are sonic waves there just like in an exhaust muffler and they if getting timed right greatly increase noise if the setup is messed with. You have air going into engine but some of it backs out to come back out the intake at certain rpm when the lengths and displacement of the intake tract line up wrong to do it. They often correct by adding airbox volume (empty dead-end box to make you go ????, it is a wave strength absorber) to alter the resonation frequency of the tract and it stops much noise. As well, the resonation control method can add a decent chunk of very low rpm torque as the resonation at lower speeds can mess with the injection in intake ports to create backflow that affects off idle performance.
Thank you for the beautiful explanation. I don't doubt you, but wouldn't the PCM on these newer cars correct the timing and intake to the adjusted airflow? It's hard to quantify but it seems a lot of people enjoy these variations to the stock induction system (e.g. open lid, open air filter, snorkel delete, intake resonator delete), albeit they might not understand how they're affecting the system. Or is it a matter of trade-off / personal preference...
 

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There are a million ways to drop pieces of induction by virtue of modification and many are beneficial, just no way to know which ones until done. The PCM DOES make up for timing and mixture but there is no way it can predict wave timing changes/effects as there is no method of reading them on the fly. It takes a laboratory to do that.

You can adjust for airflow in and of itself but pretty hard to for some of its' effects. How do you measure air that has been through the MAF once then backflowed back through it to go back through it forward a second time? It measured 3X doing that, give it some thought. That flips the PCM out. What resonation does. Waves timed correctly can make big power (2 stroke expansion chamber, up to 25% power increase) but not timed correctly just mess things up.
 
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