HOW-TO: EvansFab Mountune's stock box plus scoop vent mods. It's a 2-fer!

[HaveBlue83]

I am a DIY How-To guy. For my next two tricks I shall make a Mountune-style airbox out of the OEM box, and then I shall open up the intake snorkel to fresh air, but not just a hole...I did a neat little trick



What you need:

Snorkle inlet mod:
-OEM STOCK not messed with FiST with stock intake.
-torx bits for headlight
-map gas (bring the heat!)
-razor knife
-Phillips Screwdriver

Montune style intake:
-Jack
-sheet metal to cover the bottom of the cut intake
-Sheet metal cutters
-Rivets & Rivet gun
-2.5" Hole saw
-Hacksaw
-Ratched and 7mm bit
-Black Paint (optional)
-K&N Fiesta Panel Filter (what Mountune uses)
-Ball peen hammer
-Vice
-2.5" Shop-Vac hose. (8' one is $23 from Lowes or Home Depot). Comes with two ends in the box



Intake inlet:

-remove the headlight with torx bits. unplug and remove, set aside.

-pop off the 4 "+" screwdriver pop retainers that hold the bumper onto the rad support area/

-lift the bumper and take the one part of the bumper that hits the hood latch area and pop it over the top to hold it up and away. yes it is flexable. don't worry!

-take your sharpie and make a nice dry run marking of where u want to cut out. only the sides and front need cutting! I just took a line extending from the OEM scoop above out about 2.5", right up to the inner curve area in the plastic. you WILL see it when you get in there.

-take the knife, and HEAT the end with the MAP gas so that the plastic cuts like butter. cut ONLY 3 sides,NOT the rear side closest to the rad!

-after you have the flap cut, take the map gas and heat up JUST the back part that wasn't cut. you want it soft so quick passes only!. take that front flap and PUSH it down and hold it. after it cools take the knife and remove any stress areas from bending it down and heat again until you get it level. once you get that, you will need to remove the front part of the tab..it's too floppy. cut right behind that bump area. bam new intake with a scoop. An intake hole is nothing without ducting!

leftover cut off piece:

imgupload


Mountune Style OEM Lower Intake box:

-Remove the top of the intake box with the Torx bits. 4 top and one on the front.
-Disconnect the Breather line, IAT/MAF connector, Intake pipe,
-remove the filter.
-pull out the intake box.


Ok, now we are going to destroy the OEM box. Then we are going to mold a piece of sheel Stainless Steel to the bottom and make a hole for the snorkel. if you dont have Shop exp and are a drop in guy, walk away. I just went at it, so YMMV.

-OK, Vice up the box, and hack off the bottom. (LOL, literally). I left enough room for the end of the Shop-Vac hose top (modified) to clear the snorkel airflow path.

Next you will need a square of sheet metal to cover the bottom with about 1" of overlap to bend over and rivet onto the box with the ball peen hammer. cut the metal, cut releif cuts on the edges, and start hammering down.

-Next, drill rivet holes. here is the location of the holes I used. I don't have a pic of the metal on or riveted...picture didn't come out, BUT I will add one for ya soon!

-Next you need to get a 2.5" hole saw and cut a hole in the center of the metal so that it clears the rivets. this is for the snorkel. make sure it is a 2.5" one!
This pic is the finished product, showing the hole:

-After this, clean up the box, paint if you so choose, and clean out all the plastic bits.

-You need to modify the included end piece for the hose. Remove where marked. Smooth after cutting off:

-Drop the now modified intake box back into the car. Install the hose into the hole and attach the shortened end cap so that it sits inside the box and holds the hose there. pretty simple. You only need about 3' of hose to get to the area behind the fog light. it's tight there but not a far reach. this is where Mountune takes their hose to. Cut off the excess after you snake it down next to the FMIC piping and past the wiper fluid bottle to above the Fog area.

Top view:

Bottom View:

Enjoy your new Mountune-Style bottom box with asnorkel and your fresh air intake scoop for WAYYYYY Less than $330!

 

[Cruz'nFiST]

Nice write up man, this is exactly what I was gonna/want to do. I have everything I need but I've just been so busy I haven't had the time to get to it. Thanks for the pics and the time to write everything out, it makes it so much easier now, before everything was in my head. Again, great write up.

 

[HaveBlue83]

thanks! I am planning on doing the JS Performance induction silicone hose as well after I sell my injen. it's $140 shipped and cheaper than the MT one. I am digging this OEM+ style setup . I hear ya, it's all in your head formulating. I was about to save for a MT intake and I though WAIT......its a metal box......i have a plastic box......i'm making my own lol.


update: i just went and beat on the car. Got back and quick checked the feel of the intake: the top snorkel is really cold. The box is cold. The intake pipe past the Maf is cold. It doesnt get warm until the turbo crossover pipe.

I wish i had the cobb to check temps for you guys...but this def made a change. Before the box was hot with all OEM. The Injen was also warm the entire way. That duct cut made a huge difference.

 

[kevinatfms]

Id take just a 3" MAF adapter off ebay and a 3" piece of brake hose ducting instead of cutting the whole bottom of the box off. drill 4 holes in the bottom of the box and bolt the MAF adapter into the bottom of the box. Run the hose where you want and enjoy. You can even add a scoop to the bottom of the bumper(stock ride height would be best) to get the "ram air" effect into the intake box.


MAF adapter:
http://www.amazon.com/Spectre-Perfo...0-9912559?ie=UTF8&refRID=0YT9JRDHNRCNJ5S5EAWQ

Brake hose ducting:
http://www.amazon.com/Spectre-Perfo...sim_263_4?ie=UTF8&refRID=06SZ5SYHB41EWRZGRSDB

scoop to mount below bumper for ram air effect
http://www.amazon.com/Allstar-ALL42...0-9912559?ie=UTF8&refRID=0YT9JRDHNRCNJ5S5EAWQ

 

[boombots]

I like it, a cheap effective CAI. I think I would go a different route to seal the bottom. Use plexiglass or some kind of composite cut to the shape/size of the opening and epoxied it on. Then use a body filler or fiberglass filler to shape it smooth and paint it black. Nice job taking the chance to tear it apart and make a how to!

 

[HaveBlue83]

Yeah i was thinking of making it all pretty and stuff but honestly this got the job done and i had the sheet steel there. I can always get another box or redo mine with plastic. All i know is the box and intake section is cold. Thats what matters to me.

 

[Svvift]

I really like this idea.
might have to be doing this in the near future.

 

[kevinatfms]

Any measurements for the bottom of the box? Specifically the section you cut off? I want to know if the 3" MAF adapter will be too big for it or if i should just go with some 2.5" speaker port tube. They are cheap and just as effective and i can JB weld it to the box to reduce the nuts/bolts count.

This is what im talking about instead of bolting on the MAF adapter
http://www.parts-express.com/speaker-cabinet-port-tube-2-1-2-id-x-8-1-2-l-flared--260-478

or this is the 3" version.
http://www.amazon.com/Goldwood-Port-Tube-ID-4-1/dp/B000HJ5MNE/ref=zg_bs_11042161_1

cut a 3" hole at the bottom of the box, JB weld or hot glue this into place and then run the 3" brake duct hose into the lower front bumper.

 

[HaveBlue83]

There is no way you are getting a 3" tube behind the fog area or anywhere else. A 2.5" is the largest and even that is smashed a lil bit to fit.

I didnt measure the depth, i just made the snorkel clear the front oem air scoop airway.

 

[14FIst]

Awesome write up. Dumb question but what exactly does the hose do is take unused air away from the box or does the hose bring more cool air in. Sorry just trying to understand, I did the mod of cutting an opening for air to get in the factory snorkel. Thanks for any info

 

[AzNightmare]

Awesome write up. Dumb question but what exactly does the hose do is take unused air away from the box or does the hose bring more cool air in. Sorry just trying to understand, I did the mod of cutting an opening for air to get in the factory snorkel. Thanks for any info

Hose is there to draw in cooler air into the box. Usually a good spot for cool air is behind the bumper/fender, right above the fog lamp.

 

[mattkc]

I hope to be completing mine this weekend!

 

[Siestarider]

Wonderful ideas here, especially the scooped air to stock intake mod. But the lower air box hose may not be what it seems.

I bought the Mountune box when it first came out, liked the theory. While testing air dam and hood vent ideas, I measured pressures around the fog light behind bumper. To my surprise, I found negative pressure there, ie below ambient, using a differential manometer. These are at speed measurements, not standing still. But got me thinking.

So I took off the Mountune lower hose, taped lower box hole shut, and ran performance logs. Lower hose on or off Mountune box made no difference in performance (Cobb S3) on 3rd gear pulls.

Does not mean theory is bad, just means the lower hose should work better exposed to positive air pressure. Cool air is good, but if you can find a cool air inlet with positive pressure, better.

My next undertray experiment will be adding a NACA duct, testing for positive pressure, then if I have positive pressure, connecting duct to Mountune box, see if positive pressure makes a difference. It may not, our cars are tune driven and it may take tuning amendments to recognize.

 

[AzNightmare]

I'm a bit confused on how to connect the hose to the metal plate.
Can you please clarify?

Did you have to put anything around the hole to make an airtight seal?