Air Filter/Air Intake

Hey Fellas, got another question.
Got 2004 WRX with no mods. I'm not really that much into fixing my car up (yet), but I'll do simple things like changing spark plugs and getting a new air filter and such....

Tell me your experiences/opinions on air filters. K&N air filter, worth it? Notice any changes in performance?? What about cold air intakes??
Is it one of those things that you won't feel any difference unless you make mods on other parts of engine/exhaust, like uppipe, exhaust, etc.?

yea the K&N is pretty good. and if ur not goin all out a Turbo XS shorty Intake is pretty good to. so is a Greddy Airnix filter. u'll feel some difference but its not gonna be earth shaterin. and u'll get a pretty nice sound to.

I have a JC Sports short ram intake. I never really heard of the company before, but it was on the car when I bought it. According to the website, it's suppose to be pretty good and brags about 13HP gain. It didn't mess up my mass air flow sensor and sounds pretty good so ya could look into that.

I have an AEM Cold Air Intake, not the short ram. It works pretty well. Didn't notice any real hp gain but did happen to notice that the boost was held slightly better and without hesitation when bumped up.

Dude I destroyed cylinder number 3 w/ an intake and bad tuning on my part so I might be a bit biased :rolleyes:

The truth is intakes on a wrx can make the MAF nutty and cause the engine to run dangerously lean, which will cause knock. If you insist on it because your hard headed like I was =) dont run the intake without an ecu that will propery manage it.

The stock intake isnt at all restrictive, remove the snorkulus if you haven already done so and drop in a good panel filter. Use the extra cash for a catless upipe or downpipe. You'll notice a big diffrence in your rex once you start removing the cats.

Thats my 2 cents :p

Spend your money on intercooler hoses (http://www.vishnutuning.com/parts_wrx.htm). You'll get real power and no nasty side effects. If you haven't already, remove your intake silencer snorkel; check here (http://mikeegan.stormpages.com/Silencer.html) for instructions. Then just start saving your pennies for an ECU flash.

fellas, thanks for the replies/advices. I've heard of hacking that silencer snorkel, but it sounds like all it does is increase the noise, and allowing you to hear the turbine spool.... I'm not sure if I necessarily want that. I have been thinking about Vishnu stage 0, but I'm wanting to do some easier things first...

Intercooler hoses. An honest 10whp gain for $160.

wrxed, the coldair intake didnt make it too lean. Other things had to have been a factor such as boosting the turbo way too high?

If you run too much boost, the air still gets properly metered right up to the fuel cut. I too have seen air intakes cause the cars to run rich. Unless you buy the intake and *then* have your ECU tuned with the intake in mind, it isn't worth it. Again, intercooler hoses if you want a cheap upgrade.

My car runs rich from it. Assuming that the intake would make the car run lean, even slightly, it wouldnt be near enough to cause that much detonation. Really only the turbo is gonna cause that kind of detonation

i herd that WRX's computers suck. so its a good idea after bolt ons mods. to get an ECU upgrade like a Turbo XS UTEC.

Regardless of what you "herd," they're actually remarkable pieces of hardware and software which do an unbelievable job of controlling the car. As a result, most changes to the ECU are done by reflashing or by piggy-backing onto the stock ECU. That way, you retain the disaster-avoidance and variability of the stock ECU but get the improved performance that aftermarket upgrades bring.

wrxed, the coldair intake didnt make it too lean. Other things had to have been a factor such as boosting the turbo way too high?

Actually, I put a cold air intake on my wrx and within 2 minutes of driving, I got a CEL - misfires in all 4 cylinders. Got lots of knock with it too. The problem with CAI's that they usually either have a bend right before the MAF or the piping where the MAF resides is a different size than the stock piping. Either of these 2 conditions will make the MAF read incorrectly and can most definitely do some nasty stuff to your motor if you're not careful. There are plenty of documented instances of CAI's causing misfires and detonation. If you want a new intake, get either a short ram intake (Blitz SUS, TurboXS, Perrin, etc.) or upgrade the stock Panel filter to a K&N, ITG or Perrin Panel filter.

Like others have said though, there are definitely better ways to spend the cash. The stock airbox is not restrictive until you upgrade your turbo.


(Note-CAI's make no sense in a turbo charged application. The amount the turbo heats up the air as it passes through will totally nullify the coolness of the air that the CAI brings in.... That's what intercoolers are for....)

ok, if they dont make sense then how come every other extremely modded wrx ive ever seen pretty much have a coldair intake? I've installed plenty of coldair intakes on plenty of cars and none of which effected anything on the car. Something was probably wrong prior to the installation or your MAF sensor was already tweeked. Did you by chance when taking it off the airbox touch it on the spike? That will mess it up. Anyways, once hi-boost is caused airboxes tend to become restrictive. The more air the coldair intake brings in while help your car out a lot.

-I think what he is saying is that COLD air intake for turbo application is a waste. I think one could justify changing the stock air box to a higher flow cone filter of sort, but not necessary making it a COLD air intake. I did read in a couple of places that intake air is going to be heated up by turbine NO MATTER what, and the few degrees of cooler air you intake from COLD air intake is COMPLETELY negated by that process, or if not COMPLETELY negated, then the difference is so marginal that it is COMPLETELY NEGLIGIBLE.

I guess that's what more efficient intercoolers are for hey??

keita, that is exactly what I was trying to say. Thanks for the clarification. Ragnarok, I don't know what extremely modified wrx's you've seen, but all of the higly modified onesI know of don't have cold air intakes. Heck, vishnu won't even tune your car for you if you have any intake at all other than stock! Neither does TurboXS or Cobb.

And the installation of the intake in my car was correct. It was installed correctly and it still made my car stumble. I took the CAI off, and it was magicly better. And I think I would consider myself to have a highly modified WRX - TurboXS stage 4, 289awhp, 272awtq, and a short ram intake.

I really wouldn't consider that "highly modified". Modified, yes, but hardly highly IMO. I am just curious if you have even ever had your car to the track??? If so, please share your times, I am very curious... With my friends WRX, he has an average time of 13.7 at the track....after the CAI he was averaging a 13.5 to 13.6 so i dunno how you could it doesnt do anything and he has had no detonation problems or misfires and to this day still does not... Of course this is just my personal experience...

I must say that adding an intake in general removes any blockage in the intake system and should make more power..... but a CAI definitely doesn't make more power than a short intake in a turbocharged application, and the cai just has higher risk factors involved... Most create a lean condition in the engine. Here's a general question to think about.... take a look at a bunch of high horsepower turbocharged motors online(supra's, skylines, 300zx, rx-7).... notice that almost none of them use CAI's....

I went to the track one day, the best I pulled was a 12.7@106.... I'd never been to the track before that, so I'm sure someone with more experience could've rattled off something slightly faster. That was with 1.9 60'. Once I'm done sorting out my suspension, I'm gonna take the car out to a real track (one with curves!) and see what she can do there.

12.7 eh? and what do you have done to your car?

Here are all my mods...

Engine/Performance:
TurboXS UTEC Stage IV - Dyno and Road Tuned
TurboXS Active Boost Controller
Gutted OE Uppipe
Bosal Downpipe
ScoobySport Midpipe
Bosal Single-Tip Catback Exhaust
TurboXS Short Ram Intake
IHI VF34
TurboXS TMIC V2
Ultimate Racing 600cc Injectors
Walbro 255lph Fuel Pump


Suspension/Braking:
Whiteline Anti-Lift Kit
Prodrive Springs
KYB AGX Shocks
Progress Rear Sway Bar w/Heavy Duty Mounts
Kartboy Swaybar Endlinks
Stoptech OE Size Slotted Rotors Front & Rear
Axxis Ultimate Pads Front & Rear
Goodridge Stainless Steel Braided Brake Lines
Yokohama AVS ES100 215/45/17


Interior/Exterior Dress-Up:
STi Projector Headlamps
Bohmen/MCulloch 6000k HID
Lamin-X Yellow Foglight Protectant Film
Lamin-X Clear Headlight Protectant Film
STi Replica Grill
STi Replica Mesh Foglight Covers
Zerosports CF Vents
Flik Bullet-B 17" Wheels
STi Hoodscoop
Debadged 'Subaru'
Red Painted Brake Calipers
Egauges 2 Pod Pillar
VDO EGT Gauge
Blitz DTT
MOMO Race Airleather Shift Knob

I.C.E.:
Alpine CDA-7894 MP3 Headunit
Polk/MOMO MM465 6.25" Front Component Speakers w/Custom Fabbed Spacers
JL TR400-CXi Rear Coaxial Speakers
JL Audio 10w6 Subwoofer
JL Audio Slash Series 500/1 Amplifier w/Remote Gain Knob


Other/Miscellaneous:
Escort Passport 8500
Kartboy Short Shifter
Kartboy Shifter Bushings

Do you have any drivetrain mods i.e. clutch or flywheel?

Nope, totally stock drivetrain.... I'm waiting to replace my clutch... it's only a matter of time. It has already slipped a couple of times. I'll be upgrading to a lighter flywheel at that point too... And I'm expecting my transmission to go soon. The stock tranny doesn't like this much power. I baby it though so it should last for at least a while longer.