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Old 02-19-2021, 09:31 PM   #1
Bhintz1288
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Default "Stock" Cold Air Intake CAI (DIY)

Not sure how this will be received. Do or do not.. but I did. For all I know this is a thing already. So used the OEM air box and cut out the 'tube' portion which also houses the MAF. Made short work of it with a Dremel multi-tool with a saw blade and regular Dremel with a sanding tool. Then finished it off with a super high-end Spectre filter





**If opinions are strong enough I may always route it even 'more stock' thru the fender and have it pop back out into the engine bay (or just leave in fender).. I assume it was like that as stock to make it quieter?? Would likely reduce turbulence as well.

I look forward to ALL input.
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Last edited by Bhintz1288; 02-20-2021 at 06:51 AM.
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Old 02-19-2021, 09:48 PM   #2
murrdogg24
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what you made is actually a "hot" air intake lmao..
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Old 02-19-2021, 09:55 PM   #3
Bhintz1288
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Wrap it? Route into fender?? Return to stock???
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Old 02-19-2021, 11:41 PM   #4
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Quote:
Originally Posted by murrdogg24 View Post
what you made is actually a "hot" air intake lmao..

No different than this, methinks.


https://forums.nasioc.com/forums/sho...php?p=46297177
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Old 02-20-2021, 01:41 AM   #5
murrdogg24
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A true CAI goes through the fender and draws in cool air from the wheel well....the way you have it is only drawing in hot air from the engine bay.

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Wrap it? Route into fender?? Return to stock???
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Old 02-20-2021, 06:50 AM   #6
Bhintz1288
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Originally Posted by pw- View Post
That thing is sweet!

I reckon I'll extend a little and shove that thing into the fender. Mainly needed a housing for the MAF that wasn't a box. Thanks for all input!
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Old 02-20-2021, 01:33 PM   #7
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I feel you are not going to welcome ALL of the feedback this is going to get you, just sayin!
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Old 02-20-2021, 07:10 PM   #8
Bhintz1288
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Nahhh, I knew it would be controversial. I am honestly more worried about the turbulence which the sensor so close to the inlet, I am newb so idk if that would even cause a problem but seems like it could. But stock set-up has it sucking from practically the exact same spot so I figure at least it declutters the engine bay a little. Again, very likely going to plug it into the fender in the near future.
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Old 02-20-2021, 11:01 PM   #9
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...and why did you think the stock box was bad or a bad design?

GTI owners do this all the time; lop off the stock air filter box next the fender and pop on a cone filter. however, most kits put some sort of shield between the filter and the engine to isolate it from the heat of the engine.

Also, are you going to leave the stock intake snorkel in place to help bring in air to that side of the engine bay?

I guess as long as you block the heat of the engine and route outside air to the filter location, I suppose what you have could be a "cold air intake"; however, now you a filter on a stick and a chopped up stock air box.

Did you do any befores and afters?
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Old 02-21-2021, 08:10 AM   #10
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Lol, honestly combination of boredom and lezzbereal, it does look better than stock. Maybe I need to go get a GTI The wall idea came to mind too but may be more difficult than just extending intake into fender.

I wanted to get sarcastic and say I did some physics calculations and such and realized that Subaru had made some critical mistake with their intake... but it's too early in morning for all that Honestly, thank you for all input.

I don't have a true before and after but I think pretty close. Will see what I have to upload a lil later today. Cheers!
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Old 02-21-2021, 12:22 PM   #11
spectr3
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This looks like some **** I would do. I like it.
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Old 02-21-2021, 02:37 PM   #12
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We can only guess at what exact car you have since you haven't filled out your profile. But anyway-
The stock tune in the ECU is calibrated for the airflow characteristics of the stock airbox. By making it into a CAI or HAI or whatever, you've altered that calibration. So just like with an aftermarket intake you'd now need a tune for proper A/F, and since the intake is custom it would have to be a custom pro-tune for your setup. Driving it as-is with no tune, especially if driven hard, could be unsafe for the motor.
There are reasons why you don't see everyone else doing this, it may be perfectly fine on other cars (at least as far as not blowing things up, still likely more of a noisemaker than power-adder) but not so much on turbo Subarus.
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Old 02-21-2021, 08:43 PM   #13
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Lightbulb A different take

Quote:
Originally Posted by Bhintz1288 View Post

The wall idea came to mind too but may be more difficult than just extending intake into fender.
Why build a wall when there's already one there?

When I got my JDM GF8 STi, it was missing the entire air intake resonator which was supposed to be located inside of the right front inner fender. The air intake snorkel led to the inner fender, and the air filter box did as well, but they weren't actually connected in any fashion.

I wasn't worried about keeping the intake "quiet"... so I figured I'd create my own version of a true cold air intake.

As the two photos below show (with the MAF and top temporarily removed from the factory air filter box), I used a PVC elbow to go from the air filter box to inside the inner fender. I forget what size it was (3"?), but it fit the filter box opening perfectly. I created an air intake opening in the right-hand side fog lamp location, which feeds directly into the inner fender. The Intake Air Temperature sensor was moved from the deleted snorkel to the inside of the inner fender. All openings from the engine bay to the right side inner fender were sealed off (including where the factory air snorkel used to go), thus eliminating hot engine bay air from entering the inner fender.

I don't believe I've modified the air intake to such a degree that a "tune" would be required (as the factory airbox/filter has been retained)... and with no intake resonator, I'm hearing all the beautiful racket that this EJ20K produces. I'm quite pleased with how it all worked out.




Last edited by Vancouver98STi; 02-22-2021 at 04:12 PM.
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Old 02-22-2021, 12:42 AM   #14
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Looking forward to seeing Unabombers post.
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Old 03-26-2021, 04:11 AM   #15
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I kinda like it. How's the sound? Any performance gain?
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Old 03-26-2021, 02:43 PM   #16
Vancouver98STi
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I kinda like it. How's the sound?
Are you referring to my modified factory air intake? If so... I kinda like it too. The car still has the complete factory STi exhaust on it, so the exhaust note is relatively quiet. However, that doesn't mean I don't hear anything when I put my foot into it. Under hard acceleration, the engine has a very deep mechanical growl. It sounds like a large angry robotic beast that's been poked with a sharp stick. With this being a JDM vehicle, and RHD, I'm sitting even closer to the modified air intake. Talk about having a front row seat at an event!

When I bought the car, it had an aftermarket BOV installed. Maybe it's because I'm an old fart, but I couldn't stand the near constant racket of it venting to the atmosphere. Fortunately, the factory BOV also came with car, so I swapped it back in. With my modified intake, I can still hear all the turbo sounds that I want to hear just fine.

Quote:
Originally Posted by brylemr View Post

Any performance gain?
I modified the intake as soon as I got the car (as the intake resonator was already missing, and I didn't like the way the intake was half apart), so I can't honestly say whether it made a difference performance-wise compared to the factory setup or not. But it pulls real hard, and sounds great. I'm a happy camper.
.

Last edited by Vancouver98STi; 03-26-2021 at 07:58 PM.
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Old 03-26-2021, 02:59 PM   #17
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Quote:
Originally Posted by murrdogg24 View Post
what you made is actually a "hot" air intake lmao..
Yeah I think OP's going to see higher intake temps with this. You'll need a tune to avoid running to lean as well. You basically rotated the intake to be closer to the highest heat generator in the bay, the turb.

If you call any performance shop they will tell you that the stock intake is perfectly fine and you're better off doing a full turbo back system.

Its not until you go MAF sensor-less, that changing intake makes huge gains.
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Old 03-26-2021, 07:45 PM   #18
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Quote:
Originally Posted by murrdogg24 View Post
what you made is actually a "hot" air intake lmao..
my thought exactly.

It looks cool though, sure it makes a pleasing sound, and bonus points for a creativity. In my opinion thats not worth the risk of unfortunate complications that change might have created.
Hope theres no negative side effects though. To each their own.
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Old 04-01-2021, 10:43 AM   #19
my name is joe
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The stock intake is usually 2-5 degrees hotter than ambient when driving. That mod you did will definitely be hotter. Take air coming in from the foglight or air from the bumper.
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