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2006 Outback 3.0R, 1992 SVX 3.3 turbo, 2007 Forester 2.0
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49 Posts
You can do the same things that work for all MAF Subarus:

1. Drop-in hi-flow panel filter of your choice - I always use K&Ns
2. Eleminate the "funnel" & feed the air box via a 3" piece of tube drawing air from the fenderwell.

You'll have an intake growl @ WOT after # 2 is done, but both will give a noticeable power increase.
Has anyone logged the MAF and intake pressure signals before and after the intake mods? The total loss across the whole intake system seems to be in the order of 1 PSI at full song on an EZ30R.

Very easy to do with romraider, for example - pls see attachement.

- edit: I looked at K&N pages - the element flows 460 cfm @ 1,5" of H2O. 1 PSI is 27,7" of H2O and the MAF @ full song was 218g/s, which is 386 cfm at 20C and sea level (1013mbar). The 1 PSI delta p across the whole intake equals roughly to 15 horse power... all this combined means that there may be room for improvement by swapping the filter element to a "free flow" type, but only above 4k rpm. I will try and log the data, back to back with an OEM filter.

Kind regards,

Tapani
 

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2005 Legacy 2.5i Wagon 4EAT; 2005 Forester XS 4EAT
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672 Posts
For the H6, would the filter box from an H4 fit? I think the filter size is the same. In theory, wouldn't this make this mod easier to do on the H6 cars? I'm sure I could find a box in a local junkyard.
 

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outback 2.5L 5 speed wintergreen
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17 Posts
would you still get colder air if a you had a cone filter mounted to the top of the wheel well under the hood away from the motor with a DIY tube going to the airbox??? I drive on a lot of sinders during the winter and spring, and am worried about the dust from the roads being sucked through with the fender intake mod.
Tanner
2002 OB 2.5
 

· Registered
2002 Outback Wagon 2.5L Auto Weather Package
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1,970 Posts
Not exactly. If you are moving fast enough, but not towing or pushing the engine hard, there is some data that says the air under the hood doesn't get too incredibly hot - but chances are in much if not most of your driving it will be hotter than if you pulled from either the fender or the front horn. I've been looking at putting some stainless steel screen behind my grille to reduce the cinder and gravel bits finding their way into my radiator, which would also allow me to remove the deflector mounted on the hood to keep them out of the intake.
 

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01 VDC, 05 R Sedan, 06 BAJA EJ257
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19,149 Posts
I did something like this on mine and triggered the forbidden 0420 code????
I don't think so. It had to be something else.

would you still get colder air if a you had a cone filter mounted to the top of the wheel well under the hood away from the motor with a DIY tube going to the airbox??? I drive on a lot of sinders during the winter and spring, and am worried about the dust from the roads being sucked through with the fender intake mod.
My filter is in the fender. About 5k miles since the build had the car running and the filter is still clean and I don't have issue with water. The inner fender skirt keeps debris and water from blowing up to the filter. Pic is when ?I was constructing it.
 

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'02 Bean H6, AWP & ORP, factory hitch
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3,110 Posts
On a car I previously owned, (01 Civic Si) I used an AEM cold air intake fortunately designed for my car. My concern, since I lowered it 4" for weekend SCCA events, was that the cone filter ened up much lower to the ground. To help prevent the intake from sucking water if I happened to go thru a puddle deper than I anticipated, I cut the tube and removed 1" of the aluminum. In it's place I installed a "secondary" filter, which comprised of a perforated piece of urethane, slid on a small foam rubber filter and clamped it all together. Put the car thru the MAP process to ensure that the "secondary" did not draw air unless the primary was wet, or excessively dirty. Simple solution for my daily driving concerns
 

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'02 Bean H6, AWP & ORP, factory hitch
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3,110 Posts
Now the question is how to do something to the 02 H6 I currently own. It's a shame that there are so few bolt-on mods are available for the Outback. For example, I really would like someone to provide a cat-back exhaust system. Simply for better flow. I do not feel like fabricating a mandrel bent system myself, especially since one of the things I like best is the clearance my OBW provides. In this car I do not have to be concerned with leaving parts behind after going over speed bumps and train crossings, etc.
 

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2000 Subaru Outback Limited, Manual Transmission
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713 Posts
I've got the pieces to do this setup myself, but I plan on using the stock scoop/duct thing. I have an OBDII scanner on the way that does real-time fuel economy and power. I plan on experimenting with different setups to see what the changes are (if any).

I just have a cheap $10 air filter now, couldn't justify the $40 for a K&N, but I might just it with a piece of foam or something to see if there's any changes with that.
 

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01 VDC, 05 R Sedan, 06 BAJA EJ257
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19,149 Posts
You know you can buy cotton filters that are not label "K&N" on the cheap and they are washable in the exact same manner down at your local parts store. Just remember to wash it out regular no matter which you get.
 

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'02 Legacy Outback Wagon - Wintergreen Metallic - 4EAT - Electrical grounding mod, custom intake mod
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19 Posts
Discussion Starter · #53 ·
Hello all,

It's been a LONG time since I have logged into the site. Since my last log in, and date of the original mod here are some things I have noticed.

First I would like to inform you all that I have logged 45,000 miles on my car since I have done this modification.

1 - Because I did not use any form of sealant or bonding agent, I have had to replace the center section of the intake pipe setup. This is due to the "friction" fitment of the pieces and the amount of miles driven.

2 - I have driven this through ALL kinds of weather conditions, and have NEVER had any problems with water, slush, or snow coming into the intake.

3 - I now have 172k on the odo and I am still getting 19-21 mpg in the city, and 27-30mpg on the highway. I don't know of many other older vehicles that still can get this kind of mileage.

Hope this helps to answer any questions.

Keep up the modding, and enjoy the drive!!

Darksyde :29:
 

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2000 Subaru Outback
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2 Posts
Hi Darksyde. Have a question regarding your "red cable mod". I'm interested in more info on the effect it had on your idling and exactly how you connected and routed the cables. Do you have a post showing this mod? If not, could you offer up some basics on how and why it works?

Many thanks...

Edit: Should have searched your posts 1st. My apology. I found the topic regarding the wiring mod. Thank you for sharing!
 

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'02 OBW H4 Base 4EAT
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33 Posts
Hi everyone! I was wondering what the big black "air box" as well as the other random plastic pipes are used for? On the intake manifold, there are a few weirdly-shaped pieces. Is it solely for reduced air-intake noise?
 

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22,837 Posts
Hi everyone! I was wondering what the big black "air box" as well as the other random plastic pipes are used for? On the intake manifold, there are a few weirdly-shaped pieces. Is it solely for reduced air-intake noise?
Couple of things, stock intakes will have a designed low point to help catch water before it gets to the engine, they also have built in parts that help address intake noise, and the box size and some times shape helps provide a volume of air so as the engine speed changes the box of air helps even out the intake demand ie lesson the need to suck more air before the engine gets what it wants etc. There is quite a bit of engineering that goes into measuring how much air the engine needs or might ask for and the intake layout gets designed to help address that.

Which is why its pretty funny to see kids rip out their stock cold air intakes and install hot air intakes under the hood with big filters - this actually can reduce power by a sizable % though it can make the car sound louder. Replacing the stock intake you need to replace it with cold outside air - and with enough volume to match the old intake. Increasing the amount of air the engine can get will only change your power if the engine then gets tuned so it knows that it now has more potential air it can mix with more fuel otherwise all your doing is trying to provide more air to an engine that only needs and uses X air to start with. LOL
 

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'02 OBW H4 Base 4EAT
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33 Posts
Yeah hahaha! I never understood why people were so eager to rip out the 'flawed and awful' yet precisely engineered intake. The only reason I considered it was to make room for a second battery, but I was turned away from that approach pretty quickly. Anyways, the air is drawn from the very front-most point of the car, right behind the grill. I can't think of any better way to draw colder air... Seems funny for people to draw it from.. the wheel well? wtf? With the scoop at the front, it protects from rain, and in any case, it 'forces' more air into the ductwork (air rushing forward at 45 mph straight into this foot wide scoop). Seems silly lol
 

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2002 Subaru OBW 2.5l SOHC 4EAT
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16 Posts
My attempt

So, I haven't done anything lately with the Subaru. Then I noticed the CAI was all cracked up, somehow got a hole the size of a quarter in the front cone, etc. So I got all excited to do a mod and checked up on here for ideas. This is what I did.

Went to Lowes:
23445 3-IN x 2-IN Flexible coupling ($6.52)
23485 2-IN Flex Elbow [45 degree] & (included) Clamps @ 2 ($14.54)
42368 2-IN x 5-ft ABS DWV Pipe ($5.75)

I could have got the 2-ft ABS pipe, but I have a gardening project my wife wants done, so 2 birds....

I took off the old CAI up to the filter box, making sure to put back all the bolts.
Took off the old flexible rubber hose (OFRH) from the old CAI.
Shoved the coupling into the hole on the fender side.
Shoved the first flex elbow onto the air box. It was a PIA, had to take off the box and use a long, flat screw driver to leverage the last part up over the lip. Then I put the box back on, and lined up the elbow the way I wanted.
Took the OFRH and shoved the elbow into it. Tightened down the clamps.
Then shoved the other flex elbow into the other side of the OFRH. Clamped it down.
Cut off a piece from the ABS pipe and stuck that in between the coupler and the elbow. Clamped down. Wallah!

Best $28 bucks I have spent in awhile.
 

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