Cold Air, airbox.. ?

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Cold Air, airbox.. ?

Postby MrEs » Tue Jul 24, 2007 10:26 pm

Background:
A long time ago I did a resonatorectomy and I love it, the extra spool noise, and the small 'bov' style noise. And the scientific 'seat in the pants' dyno says it gives more power :whistle:
But does this allow more heat to get into the intake...?


Purpose:
Looking at the image below you can see that there is a chance to tidy things up a little and ensure that only cold air from the guard gets into the airbox and none of the warmer air from the engine bay goes in. I have no idea if this make any difference but if feels good anyways.
Image
We have a situation where the air will get sucked into the hole where the air intake scoop ends; and also air will go behind the airbox and straight in as the box isn't sealed from the engine bay...


What you need:
You'll need a 90mm PCV pipe with a 'female' expander end (where another 90mm part can potentially fit in). The entry hole into the intake is EXACTLY 90mm and to fit the PVC pipe is actually a bit of a push, its fits very snug and air tight.
Another great item is the plastic cap that goes over the hole where the air-intake scoop leads to. I bought it from Subaru in the U.S
https://www.subarugenuineparts.com/prod ... cts_id=704

Image
It was only a few dollars and shipping was basically nothing because i was buying a few other things from them.. :)



Procedure
This assumes you've already followed lupins resonatorectomy:
http://www.wrx.com.au/forum/viewtopic.php?t=13910

Now most of us have done a resonatorectomy, and are left with a gaping hole after the intake snorkel and an OEM airbox that can/will suck in hot air from the engine bay. I've tried to tidy/fix this up a little. It's not 100% but it makes my feel warm and fuzzy to think that I've tried... :P

Firstly, undo and remove the intake scoop
Image

Now we take off the top of the intake box...
Image
Unclip the hoses marked in pink, undo the clips marked in green and unscrew the clamp marked in red. You can now pull off the AFM hose (marked in yellow) and take the top of the airbox off.

Now we have this:
Image

We have to undo the two bolts marked in red:
Image

Now we can pull out the bottom of the airbox. We can see in the following picture that there is a rubber seal that would make the intake hole smaller. With the seal in place the diameter is about 75mm, with the seal removed its 90mm EXACTLY. We need to remove the seal by undoing the four white clips.
Image

Next with the PVC pipe, cut it where peak section of the expanding bit is…
Example diagram:
Image

Real picture:
Image

Test fitting the PVC:
Image
I used good old shoe goo to seal the three holes that were left from the white clips that we took out earlier...

Not put the bottom half of the airbox back into the car, and we're going to have to install the PVC pipe. We can only fit the PCV pipe with the airbox in place because we have to do it from the reverse side, from the inside of the guard as it's the only way it fits. See diagram.
Image

Fit the cap that i said that you'd need:
Image

Fit your "High Flow" flat panel filter... and re-fit the top of the airbox. And hey presto, your airbox is more properly sealed and ALMOST taking in only cold air! :thumbs:
Last edited by MrEs on Sun Jul 29, 2007 12:44 pm, edited 1 time in total.
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Postby KevO-954 » Tue Jul 24, 2007 10:34 pm

Great DIY there Denis, but if you want to keep heat out you should look at insulating the plastic airbox with something like your dynamat. Kev. :thumbs:

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Postby Fisher » Sat Jul 28, 2007 11:21 pm

Nice work on the DIY, went at it today and it was a nice satisfying job :)

http://i128.photobucket.com/albums/p180 ... Medium.jpg

Note to self: remember to plug in AFM cables etc in after use...*Puts in reverse* "oh hey the check engine light is on..wtf...*splutter sounds*" etc :oops:

Where did you get that plastic cap that covers the old intake hole? I'm very interested as i didn't think anything like this was around.

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Postby The STiG » Sun Jul 29, 2007 11:43 am

NOICE work on the DIY....... well done mate.
Ada///M.

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Postby MrEs » Sun Jul 29, 2007 12:43 pm

I bought it from Subaru in the U.S
Image

https://www.subarugenuineparts.com/prod ... cts_id=704
It was only a few dollars and shipping was basically nothing because i was buying a few other things from them.. :)

I bought 5
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Postby MrEs » Sun Jul 29, 2007 12:46 pm

KevO-954 wrote:Great DIY there Denis, but if you want to keep heat out you should look at insulating the plastic airbox with something like your dynamat. Kev. :thumbs:

:giggle: that would be cool! Some results I've seen indicate that the Subaru box actually does a really good job and keeping the air cool :thumbs:


The STiG wrote:NOICE work on the DIY....... well done mate.
Ada///M.

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Postby Razgriz » Tue Jul 31, 2007 10:15 am

MrEs sorry if this is a noob question. But the cold air from the side fender, where does that come from? On the bugeye is it from the small holes near the foglight?

I also had a look at the resonator and it was pretty dirty. I was wondering if maybe more dirt came in from the fender area. And possibly water :(

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Postby MrEs » Tue Jul 31, 2007 12:43 pm

kayd wrote:MrEs sorry if this is a noob question. But the cold air from the side fender, where does that come from? On the bugeye is it from the small holes near the foglight?

I also had a look at the resonator and it was pretty dirty. I was wondering if maybe more dirt came in from the fender area. And possibly water :(

The air from the inner guard would come from heaps of places, all from outside the car. If you look inside there you will notice a fair amount of light gets through, from behind the foglight/cover, from around the panels, from around the outer skin and from the suspension area. There is more then enough air coming into the area for the engine to lap up :wink:


Any dirt in the resonator would mean it comes through from the intake scoop that comes from the front of the bonnet. I've been running resonatorless for the entire time I've had my car, that includes a few dirt motorkahanas, lots of mud play and driving around every day in rain, snow hail and shine. You shouldn't any any issues, hundreds of people from this site have done it
:thumbs:

in fact just the other week we ran a mud motorkhana with LOTS of dirt, i've since taken my filter out to have a look and it was totally clean :?

Example of what we were doing in the mud:
Image
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Postby Razgriz » Tue Jul 31, 2007 2:40 pm

Thanks for clearing that up.

The dirt was actually on the outside of the resonator. I also have a cold air intake so i was a bit worried about that.

I found this on Wikipedia...

When using a cold air intake, there is a potential risk when driving in the rain. This is often referred to as "hydrolock", and according to the automotive portal, MODsearch:

"Say it's raining cats and dogs and you're out for a spin in your car. Normally you'd love to rip through puddles without thinking twice, but because your engine is now getting air from inside your bumper you have to be careful. If your engine manages to suck up any amount of water through the intake and into the engine you will probably have little to no horsepower left. In more extreme cases, the water brought into the engine through the intake can actually break connecting rods in the pistons, as water will not compress at all, unlike air. In other words, be careful."


I was thinking about either...

removing the fog light and putting a tube through to allow more cold air into the cold air intake, and then putting a waterproof material over the air entrance to stop water and dirt

or

Because there is a big air trap in the bugeye fog lights i was thinking about maybe putting fog light covers, not STI ones just normal impreza ones over the fog lights for... (please don't tease me) better aerodynamics. :wink: and then during track days taking off a fog light cover to reveal the cold air intake hose.

any suggestions?
Last edited by Razgriz on Tue Jul 31, 2007 3:36 pm, edited 1 time in total.

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Postby Razgriz » Tue Jul 31, 2007 2:41 pm

awesome photo by the way.

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Postby MrEs » Sat Aug 04, 2007 5:33 pm

i know i couldnt live without my foggies, and i would think that once the presure built up then the aerodynamic diferance would be negligable... :?:

but i like the idea of having it removable and then a pipe to the CAI for track days :thumbs:
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Postby cpitts » Thu Oct 04, 2007 9:22 pm

Denis, just a couple of things on this one.

1) It's still worth leaving the hole open and the factory over radiator duct in place to feed the guard/air-box. Personal view, but I think once the turbo's spooling at it's max, I'd rather have a steady feed of air pressure from the front of the car into the guard.

2) Just with your flared pipe setup, you should have the FLARED end on the outside of the air-box so there's less end pipe resistance when air is drawn.

Not saying that having the pipe flared on the inside won't help as well (it will!) just that you need the other end flared as well to ensure MAX flow into the box under suction. Which is always in this situation. ;)
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Re: Cold Air, airbox.. ?

Postby MrEs » Mon Mar 10, 2008 11:19 am

bit of a delay as i didn't see these posts...but...


razgriz ^^
I've never heard of anybody getting hydrolock with anything but an in guard filter, not to say it can't happen i guess anything is possible but it's not something i think about with this setup... hydrolock is the only reason i haven't gone an in guard CAI and if i was going to mod the air intake I'd get an AVO 'in-bay' intake and buy/make an airbox for it ;)



cpitts wrote:1) It's still worth leaving the hole open and the factory over radiator duct in place to feed the guard/air-box. Personal view, but I think once the turbo's spooling at it's max, I'd rather have a steady feed of air pressure from the front of the car into the guard.

Would also like to put the snorkle back in but seal it air tight at the end that goes into the guard...
One day in the future :thumbs:

cpitts wrote:2) Just with your flared pipe setup, you should have the FLARED end on the outside of the air-box so there's less end pipe resistance when air is drawn.

Not saying that having the pipe flared on the inside won't help as well (it will!) just that you need the other end flared as well to ensure MAX flow into the box under suction. Which is always in this situation. ;)

I did flare the outside and only the outside...
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Re: Cold Air, airbox.. ?

Postby MrEs » Mon Mar 10, 2008 11:21 am

oh yea, and the reason i went back to look for this post...

http://www.rallysportdirect.com/shop/be ... -3061.html

Image

The Beatrush Air Funnel for the 02+ WRX and STi factory air box lets you pull cold air in from the fender without having to install a cold air intake. This gives you the extra performance of a cold air intake without the troublesome issues with your MAF sensor. A great part for anybody looking for more power on a factory intake.


$165.00!! :shock: :shock: :lol: :lol:

As you can see, they also blocked off the hole where i put the fender plug... ^ (with some plastic bag material :lol: )
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Re: Cold Air, airbox.. ?

Postby cpitts » Mon Mar 10, 2008 12:59 pm

MrEs wrote:
cpitts wrote:2) Just with your flared pipe setup, you should have the FLARED end on the outside of the air-box so there's less end pipe resistance when air is drawn.

Not saying that having the pipe flared on the inside won't help as well (it will!) just that you need the other end flared as well to ensure MAX flow into the box under suction. Which is always in this situation. ;)

I did flare the outside and only the outside...

Ye, soz for that Dennis, saw this pic above and it looks like the flare was on the inside :?

Image

My bad..... :oops:

Hows the $165 ($US no doubt!) brass item tho :lol: Pwn3d!!!

On the sealing around the std CAI into the guard, you can get a rubber guide from Clark Rubber that's made to sit over the edge of metal (it's U shaped) and when put right around the edge of the hole, forms a pretty good edge for the stock CAI to sit into. Alternatively, you could use tubular foam (like on the knacker bar of a BMX) and it'd do the same thing. You'd be able to wedge the CAI in there easy as!
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To fit: Sil intake, ECU, 3 Port, Walbro
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Re: Cold Air, airbox.. ?

Postby MrEs » Mon Mar 10, 2008 1:54 pm

cpitts wrote:On the sealing around the std CAI into the guard, you can get a rubber guide from Clark Rubber that's made to sit over the edge of metal (it's U shaped) and when put right around the edge of the hole, forms a pretty good edge for the stock CAI to sit into. Alternatively, you could use tubular foam (like on the knacker bar of a BMX) and it'd do the same thing. You'd be able to wedge the CAI in there easy as!

Awesome will start to check that out after the audio system is sorted :cheer:
Will post my findings in here :thumbs:
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Re: Cold Air, airbox.. ?

Postby cpitts » Mon Mar 10, 2008 1:59 pm

Ya ever get the feeling that you build up all these little things into a car and then all of a sudden 3-4 years have passed and you sell the car as a perfect final specimen?!?!?! :lol:
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Re:

Postby namzz » Sat May 17, 2008 8:14 pm

MrEs wrote:I bought it from Subaru in the U.S
Image

https://www.subarugenuineparts.com/prod ... cts_id=704
It was only a few dollars and shipping was basically nothing because i was buying a few other things from them.. :)

I bought 5


just got one from makin and luby, they are $9.

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Re: Cold Air, airbox.. ?

Postby T-Rex » Mon May 19, 2008 8:22 pm

Im going to tackle a CAI using the front right fog light and some A/C ducting into the airbox soon, i have a pod in the bay at the moment and i think a pod in the standard box (or home made) will be a lot better!

About $60 for the blue funnel, plus some A/C ducting.
Image
Full Race wrote:A smaller a/r has less efficiency at low flow and higher efficiency at high flow. A larger a/r has more efficiency at low flow and less efficiency at high flow

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Re: Cold Air, airbox.. ?

Postby cpitts » Tue May 20, 2008 10:39 pm

Putting the pod in a box will probably reduce it's ability to suck air in an unrestricted fashion.

The upside though is that it shouldn't be sucking hot air at immediate take-off or very low speeds (like dribbling along in peak hour parking traffic). Reality is, once the car is moving, the engine bay air will be replenished cooler air from the front of the car.
'07 Lib GT Spec B <- adjusting
Done: Intake, Brakes, Stereo 90%, bars, AVO TMIC
To fit: Sil intake, ECU, 3 Port, Walbro
WWW (button below) for my Subaru/Audi dyno's, detailing, pics and mods!

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