DIY SAFE STI Cold Air Intake...

[UP2MTNS]

This is more like a cold air duct...ambient air getting redirected into the engine bay and aimed specifically at your intake. This works best if you have some kind of aftermarket intake...your stock one is better than this.

This is also designated as STI because it requires the use of your right front fog light. Its also pretty stealth, check it out...

Pick up the following parts from www.pegasusautoracing.com (http://www.pegasusautoracing.com)
Air inlet (they have several)
Air duct hose - shortest length
3 worm drive hose clamps

Parts look like this!
http://www.dirtyimpreza.com/forums/vbpgimage.php?do=full&p=596&d=1221538719

prep the area where your fog light used to be so the hose has room, you have to cut out (with a dremel) a small area in the back right:

http://www.dirtyimpreza.com/forums/vbpgimage.php?do=full&p=597&d=1221538718

Using the STI fog light cover, rivet or use small bolts to mount it behind the cover. the cover has a small plastic piece that covers the rectangular inlet, just rip that off.

http://www.dirtyimpreza.com/forums/vbpgimage.php?do=full&p=600&d=1221538854

http://www.dirtyimpreza.com/forums/vbpgimage.php?do=full&p=603&d=1221539425

On the intake side, fill up one hole (I used aluminum tape, or duct tape or whatever). Bolt/rivet clamp #1 to the firewall so that you can direct where the hose output is pointed:

before:
http://www.dirtyimpreza.com/forums/vbpgimage.php?do=full&p=598&d=1221538812
after:
http://www.dirtyimpreza.com/forums/vbpgimage.php?do=full&p=599&d=1221538834


OK...time to install.....attach the hose using Clamp #2
http://www.dirtyimpreza.com/forums/vbpgimage.php?do=full&p=601&d=1221538928

route it up throught the fender well and into the engine bay. I used clamp #3 up inside the fender well to hold it in place better, but its not necessary.
http://www.dirtyimpreza.com/forums/vbpgimage.php?do=full&p=605&d=1221539972

keep it in place with the mounted hose clamp, and trim to fit:
http://www.dirtyimpreza.com/forums/vbpgimage.php?do=full&p=602&d=1221538949

final product with cobb intake...obviously if you have other intakes, it should work just as well, maybe change the direction of the hose a little.

http://www.dirtyimpreza.com/forums/vbpgimage.php?do=full&p=604&d=1221539971

http://www.dirtyimpreza.com/forums/vbpgimage.php?do=full&p=606&d=1221540197




RESULTS:

So the reason I did this is my recent obsession with AIT (Air Intake Temperature). I've had some problems with AIT getting too damned hot and so I really wanted to find a way to get the benefit of a CAI, but w/o the risk associated with having my air filter in my wheel well.

So this isn't empirical, but through enough observation, I decided to do this and I think its worth it. What I observed is, with the current set up (Cobb intake and cold air box), there was consistenly a 20 degree difference between ambient air and actual AIT. This number would increase greatly in stopped/slow traffic....on my way up to Tahoe this weekend, I saw AIT's of +110 degrees in Sacto in 30mph traffic!!

SO FAR, since installing this, i've gotten that difference down to 12 degrees...this is with that small slot in the stock STI fog light cover....I'm thinking of cutting it open more to obviously allow more air flow/velocity. If I make it any bigger, I also have some wire mesh to keep out the rocks and birds and rodents I like to aim for ;)

I do think this is doubly effective for my setup with the Cobb air box...the cooler air will not only help keep AIT's down, but the air velocity will help keep the hot engine air out of that area as well.

What's nice is its SAFE because your intake filter is out of harms way, and nothing is actually 'sucked' up the air duct....so things like water, rocks, etc won't make it up there (especially with the mesh wiring).

This could also work for brake cooling ducts pretty easily.....overall, I think its a fun/cool/cheap/DIY mod...enjoy!

[pigpen]

cool. interesting to see what others are doing.

i recently removed my silencer/snorkus in the fender, in anticipation of installing brake ducts soon. in the meantime, i started looking for a way to rig the stock scoop to the airbox without the gp moto elbow, but the weird shape of the stock scoop foiled that effort. i plan to get the elbow as my long-term solution.

so until i install the brake ducts, i used 3" dryer duct (i got a kind that is mostly smooth, not corrugated) fits perfectly through the foglight opening with no modification and into the stock airbox with the gasket removed (because it is 3" instead of 2.75"). i use zip ties through the side of it (just thin aluminum) to hold it in place at the airbox and fog opening.

what i found was that with my fog light cover removed (on track), my intake temperature quickly drops to anywhere from -1 to +4F, depending on how fast i am moving. with the foglight cover on (on street or rallycross), the temperature doesn't drop very fast until i get into boost, but it typically stabilizes at around +4 to +8F driving normally on the street. in town it gets a bit hotter, but i just have an open hole in the engine bay where the stock scoop goes. if i didn't have plans for the brake ducts, i would probably plug that hole up and call it a day.

behind the foglight cover, the duct just comes out straight, and has a large-hole screen protecting my air filter from large rocks and tire marbles. seen in pics here (click to enlarge):
http://i217.photobucket.com/albums/cc37/stonegroovin27/Pocono%20HPDEs/th_20080824_POC_DE3_8892.jpg (http://i217.photobucket.com/albums/cc37/stonegroovin27/Pocono%20HPDEs/20080824_POC_DE3_8892.jpg) http://i217.photobucket.com/albums/cc37/stonegroovin27/Pocono%20HPDEs/th_20080824_POC_DE3_8880.jpg (http://i217.photobucket.com/albums/cc37/stonegroovin27/Pocono%20HPDEs/20080824_POC_DE3_8880.jpg)

[Galen]

i'm going to do this today with my NA setup. I have a drop in K&N but instead od the snorkus i replaced it with aluminium piping that goes to the fender well (much like aftermarket cold air intakes) Unfortunatlu im going to have to sactafice one fog light... oh well, time for rally lights!

[Galen]

Well, I did something that is much the same. ill post pics when i have them.

Thanks Jon, this made a huge difference for me!

[KevinWelker]

You guys have probably seen this before. I put this together for Ben at IWSTI after working with AutoSport Engineering who installed these on open class cars for Workum and Donneley. Works really well and doesn't involve complicated routing. http://farm1.static.flickr.com/21/95442932_1d68e7d782.jpg Autosport just used the duct to flood cold air to a filter. Worked really well. http://cl50.com/xweb/rally/Ramada%2004/Www.cl50.com%5Cx-land%5Cxweb%5CRally%5CRamada%2004/image_DSC03417.jpg.html http://cl50.com/xweb/rally/Ramada%2004/Www.cl50.com%5Cx-land%5Cxweb%5CRally%5CRamada%2004/image_DSC03348.jpg.html Here's a gravel Crew variation http://cl50.com/xweb/rally/Glen%20Helen%2011-19-05/slides/DSC05204.JPG http://cl50.com/xweb/rally/Glen%20Helen%2011-19-05/slides/DSC05183.JPG

[M_anstrom]

I tryed to install a CAI on my OBS but my mass airflow sensor doesn't fit for it... anyone know were I could find one that would clamp in...

[pigpen]

I tryed to install a CAI on my OBS but my mass airflow sensor doesn't fit for it... anyone know were I could find one that would clamp in...

CAI on a MAF NA car? i recommend reading williaty's hybrid intake thread on NASIOC. the gist is this: the MAF systems on subaru's NA cars can't handle most aftermarket intakes because of erratic readings around a certain RPM range right in the daily driving realm, so to get some of the benefit of those intakes without introducing a new problem, you use the hybrid intake.

[Galen]

here is what i did.

http://i51.photobucket.com/albums/f377/ghuntsman/_MG_8267.jpg

http://i51.photobucket.com/albums/f377/ghuntsman/_MG_8270.jpg

http://i51.photobucket.com/albums/f377/ghuntsman/_MG_8273.jpg

Cost me $13.79 at Home Depot. I used 3" drainage piping. I just used a lighter to melt and shape the piece that fits into the bumper. There is a huge difference going from hot engine temps. to ambient air temps.

[UP2MTNS]

nice work....I'd get some kind of little screen on there too. just to be extra safe.

[munozppk]

http://i51.photobucket.com/albums/f377/ghuntsman/_MG_8273.jpg

That is teh sechs!

Im looking into getting a SRI for my car, then ill find a way to do this mod.

[Galen]

nice work....I'd get some kind of little screen on there too. just to be extra safe.

Yah, my mom has some down at her house so im going to steal it when im there:muhaha:

That is teh sechs!



haha, thanks. It was pretty easy and very functional!

[wrxisthebest]

i do the smae thing.. i route dryer hosing into my stock box because i dont have a fender liner..

i just run it straight to my fog lights location(without foglights in...)

used 3 inch piping into the stock airbox right below my filter... the air comes straight from the piping only..

[pigpen]

yesterday, i re-routed my 3" hose from the fog light to the stock intake scoop. it got a lot quieter, and the intake temps went back up a couple of degrees. i had to do it in preparation for the brake ducting kit i have on the way.

[SomeoneWhoIsntMe]

You guys have probably seen this before. I put this together for Ben at IWSTI after working with AutoSport Engineering who installed these on open class cars for Workum and Donneley. Works really well and doesn't involve complicated routing. http://farm1.static.flickr.com/21/95442932_1d68e7d782.jpg Autosport just used the duct to flood cold air to a filter. Worked really well. http://cl50.com/xweb/rally/Ramada%2004/Www.cl50.com%5Cx-land%5Cxweb%5CRally%5CRamada%2004/image_DSC03417.jpg.html http://cl50.com/xweb/rally/Ramada%2004/Www.cl50.com%5Cx-land%5Cxweb%5CRally%5CRamada%2004/image_DSC03348.jpg.html Here's a gravel Crew variation http://cl50.com/xweb/rally/Glen%20Helen%2011-19-05/slides/DSC05204.JPG http://cl50.com/xweb/rally/Glen%20Helen%2011-19-05/slides/DSC05183.JPGWhat size NACA duct is this, and where did you get it from? I'm having my bumper resprayed, and while I'm at it I'm considering installing an air inlet in it.

[Draco-REX]

I'm definitely thinking of doing something like this. I'm getting way too much heat and dust from the fender. But I'm trying to figure out where I can put the scoop that won't feed my filter rain or mud.

[lorenkb]

What size NACA duct is this, and where did you get it from? I'm having my bumper resprayed, and while I'm at it I'm considering installing an air inlet in it.

Just to be clear, that is most certainly not a NACA duct. I'm sure Kevin went about it in a much more orderly fashion, but all you need is a dremel and the patience to roll the lip on the whole you cut.

[KevinWelker]

What size NACA duct is this, and where did you get it from? I'm having my bumper resprayed, and while I'm at it I'm considering installing an air inlet in it.

That started life as a small NACA duct from Pegasus Racing. That one in the photo was reshaped quite a lot by the body shop that did the final painting. when I do them there is more of the original NACA shape left.
3M body panel adhesive is what i use to bond it to the fender.

[d3v0]

what size hose clamp/hose did you get? 3' long and 2.25"-2.75 clamp?

I kind of want to do this mod with:

https://www.chaplinssubarugenuineparts.com/product_info.php?products_id=986

Would be stealth as hell eh :D

Currently on stock airbox/intake, any suggestions? Should I just rig it up to the stock or will I benefit from getting a, say, cobb short ram? I saw discussion about the danger of getting dirty with a short ram but I am wondering how this mod would affect the risk of getting my engine dirty.

[UP2MTNS]

2.75' dia

[d3v0]

Thank you!

Any other suggestions pertaining to my other questions? I had lined up a Cobb SF short ram intake as my next upgrade, but doing research on here has me weary of doing it. Will this mod fix the problem?

[UP2MTNS]

Thank you!

Any other suggestions pertaining to my other questions? I had lined up a Cobb SF short ram intake as my next upgrade, but doing research on here has me weary of doing it. Will this mod fix the problem?


well yeah...I have the Cobb SRI with the 'cold air box.....the duct'ing goes up directly to it, but the traditional 'issues' with a CAI go away because nothing is going to go all the way up there and destroy the filter like w/a CAI that has the filter in the wheel well.

actually, you need SOME kind of short ram with this....otherwise, if you have a stock airbox, you'd have to drill a 2.75" dia hole for the duct to go into.

http://www.dirtyimpreza.com/forums/vbpgimage.php?do=full&p=604&d=1221539971

[d3v0]

Seems like this mod is a "must do" then :)

[geekguy]

I'm bumping this to get year-later statuses. I just put a naca duct in my hood and I'm looking for ways to prevent water from being ingested in my intake.

[UP2MTNS]

I'm bumping this to get year-later statuses. I just put a naca duct in my hood and I'm looking for ways to prevent water from being ingested in my intake.

a year later and its all good! I even proved its 'safe' by completely destroying the front right side of my bumper and nothing got into my intake ;)

[Savenfiddy]

Im doing this sort of mod tomorrow after i get all the parts i need for my DIY 07 wrx :eyebrows: will take pics and post

[UP2MTNS]

I'm looking for ways to prevent water from being ingested in my intake.

oh...the K and N pre-filter is key for this.

every time I clean my air filter, the pre-filter has a TON more junk in it. the air filter itself has stuff, but its much cleaner, and the dirt is much more fine. Pretty good system IMO.
http://www.knfilters.com/airforcewraps.htm

size isn't critical...just take basic measurements to get the diameters right....I ended up cutting some length off mine...but they're flexible/stretch...so if anything, go a little small.


Different from filter wraps, but same idea:
http://www.knfilters.com/search/wrap.aspx

[pigpen]

oh...the K and N pre-filter is key for this.

pre-filter before the short ram intake? or the SRI filter?

I'm using a hacked and resealed snorkus now, since the brake ducts use my fog light holes, but I'm just curious what you're using to keep the water out.

[UP2MTNS]

pre-filter before the short ram intake? or the SRI filter?

I'm using a hacked and resealed snorkus now, since the brake ducts use my fog light holes, but I'm just curious what you're using to keep the water out.

pre-filter wraps around your cone filter. or you can buy square ones and just cut to fit on your stock panel filter.

how you REALLY keep water out of the intake is to don't use a true 'cold air intake' with the intake in the wheel well.

[geekguy]

My DIY NACA cold air intake worked WONDERFULLY at Rally Tennessee. Proof is attached. You can also see the attached hose that diverts air directly into my DIY airbox.

[brandon mitchel]

Installing a new air intake would get your car an additional horsepower and torque without engine overhaul. I am using a Injen cold air intake (http://www.thepartsbin.com/brands/injen/injen_cold_air_intake.html) for my car.