Introduction: Cheap Air Filter

Looking for a little more acceleration and power but don't wana pay for an exspensive K&N intake? Here is a filter I built for my 2002 Subaru Outback Sport (have since upgraded to a WRX).  This design has been specifically designed for my car, however not guaranteed to work on all cars.  Some vehicles have Air Sensors and will need more work to attach this to the new intake (may cause the "Check Engine" Light to come on).

Use at your own risk!

(WARNING: This Instructable is for use on Non-turbocharged vehicles!  Turbo vehicles create a vacuum that may cause damage to the filter which could damge the turbo, engine, etc.)

(Most parts available at Advanced auto and Lowe's)
Parts list:
3" 90 degree elbow Link - $3
Spectra Intake - $15
3" Coupling Link - $10
Black Spray Paint - $5

(Red tubing will be elaborated later)

Step 1: Remove Stock Intake

Sorry I don't have any photo's of the removal, however most intakes are a matter of nuts and bolts.  The idea is to remove everything from the intake manifold.

Step 2: Build the Intake

First step is to spray paint the pipe.  One note, I filled the ends with newspaper, I didn't want to spray inside the tube to keep it as clean as possible. Once dry, attach the filter.  The filter should have a 4" opening that fits fairly snug on the PVC pipe (yes it is a 3" pipe but the flange makes it a 4" fit).  Once on simply tighten the clamp and this step is done.

Step 3: Vacuum Line

Some vehicles will have vacuum lines.  These attach to some point on the intake system.  They have to be attached to the new assembly to allow the engine to work properly. I drilled openings to attach the custom built vacuum lines.  Since each vehicle is different it will require you to decide what way works best for your car. Try to use thick lines as it will better resist engine heat and when bent will be less likely to collapse.

Step 4: Installation

Attach assembly to the Intake Manifold.  Using the 3" coupling, first tighten it onto the intake manifold opening. Then insert the assembly and tighten. Next it is always a good measure to find some place to anchor the filter other than just at the Manifold intake.  I had a spare anchor point and made a metal support that anchored directly to the filters clamp.

Step 5: Test Drive

Now I would not recommend startin it up and take it out on a wild drive.  It is always a good idea with any filter installation that you first start it and see that all sounds good (no weird noises, vibrations, leaks).  Then take it for a slow drive so to make sure nothing comes loose and that it works fine.  Once done your car should be all set.  Try some stuff with it, see how the acceleration is and how much more power you can obtain.


myr1 made it! (author)2014-10-08

Cool idea, its easy simple cheap and give you better mpgs and few hp as well.

★★ Signature: ™ Car/Bike_007_Licenes_Plate_Hide_Gadget ™★★

curious youth made it! (author)2014-03-20

while this is a great idea in theory, the pvc pipe may cause a drop in power and air intake efficiency. it may sound a little better. but the pipe in with heat and chemical fumes (petrol etc) will slightly melt the pipe and distort. causing problems for the vehicle.

fyahya1 made it! (author)2014-01-08

want a build it your self?

gret made it! (author)2012-02-08

Please note that this installation will decrease hp because of ingestion of hot under-bonnet air. You MUST isolate the intake so that it gets cool (ambient) air , otherwise you're better off with the factory airbox.
Also note that the ram-air effect is is exceedingly small at legal speeds...

candle360 made it! (author)2010-04-12

Nice Subie. I made my own cold air kit for my neon using stock piping. I had to use two pipes, and cut one of them. Nice instructable though. Definitely nice work

Achan20 made it! (author)2010-03-18

WOW. verry nice! when i get a lil cash i might do this to my 1989 subaru. yer rite its better than paying out the butt. once again nice. :)

Yerboogieman made it! (author)2010-02-13

To actually get horsepower out of this, I would put the filter in the front of the engine near the bottom part of the bumper. Ram air.

scubaru made it! (author)scubaru2010-02-20

Well essentially that would be a "Cold Air Intake" then, and true it would increase performance, but on a naturally aspiring engine you wont see much more HP. Now on my Turbocharged WRX I went K&N full Ram Air and you really feel and hear it working and increasing HP. When I built this I had $50 to spare and this is what I came up with.

Thanks for commenting.