DIY - Air Box Mod

Titan4x4Aggie · 09-28-2004, 06:38 PM

In the event that you dont want to spend $250 for 5 hp (I don't), this is an easy way to increase air flow into your engine and put a little more growl under your hood.

~~~ HIGH-FLOW FACTORY AIR BOX MOD ~~~

Step 1 (Picture 1) - Loosen the intake hose clamp (Red Arrow) and remove the two air box lid clamps (Green Arrows)

Step 2 (Picture 2) - Remove the air box lid and unclip the AFM wire clip. Set the lid aside. Remove air filter, and notice the dirt located at the base of the filter (Red Circle) because the "snorkel" has restricted air flow (reducing power). Remove the top screw (Green Arrow) and loosen the interior screw (Green Arrow) -- it will stay connected to the box. Do not worry about removing the screw you cannot access, it does not need to be removed.

Step 3 (Picture 3) - Remove the bottom of the air box by pulling up on the box with a firm, constant force. The remaining inaccessable screw by the washer reservoir (Red Arrow) will stay attached to the engine bay, and the box will come out with the lower rubber grommett still attached (Red Circle). Remove the zip-tie clip holding on the 1/2" rubber hose to the air box base.

Step 4 (Picture 4) - Mark the plastic to be removed with a pencil (Yellow Line), and remove the "snorkel" from the air box base. The easiest way to do this is to pry up the plastic around the lower clip (Red Arrow) and then pry up the plastic behind the upper clip (Green Arrow). DO NOT PRY TOO HARD, THE PASTIC WILL BREAK. You cannot deform the "snorkel" to get it out, you must gently and slightly deform the plastic around the clips. This will allow the "snorkel" to be easily removed.

Step 5 (Picture 5) - Use a hacksaw to cut the extra material off the "snorkel". Give yourself about 1/4" - 1/2" breathing room from the pencil line, in case you dont make a good cut. One straight cut at 30-45 degrees will work fine.

Titan4x4Aggie · 09-28-2004, 06:41 PM

~~~ HIGH-FLOW FACTORY AIR BOX MOD (Continued) ~~~

Step 6 (Picture 6) - Use a box cutter / razor blade to "de-burr" the edge of the "snorkel" and smooth it out. Remove any sharp edges and any loose plastic.

Step 7 (Picture 7) - Put it back in. Dont forget to put all clip / zip-ties / hoses / wires back in their correct places. Also, dont forget to tighten your hose clamp.

ENJOY YOUR FREE HP!

**goathead** · 09-29-2004, 06:00 AM

that is great. i was thinking of doing this. do you think it would be easier to just use a dremmel tool to do this? ya know, leave it all in there and just cut? no reason not to in my opinion. just a thought. btw, very nice instructions.

steve

Gig'em · 09-29-2004, 01:04 PM

Leave it to an Aggie to post idiot-proof instructions. Gig'em!

Titan4x4Aggie · 09-29-2004, 01:08 PM

you could dremel it, but it runs right next to the air box base and you run the risk of slipping and cutting a hole in your air box.

if you bend the plastic around the clips, the clips will fit under the plastic and the "snorkel" will pull out.

before you put the cut tube back in, just bend the plastic that was around the clips back down and the clips will lock back in, securing the cut "snorkel" back into the air box base.

Titan4x4Aggie · 09-29-2004, 02:36 PM

Quote:

Originally Posted by Gig'em

Leave it to an Aggie to post idiot-proof instructions. Gig'em!

i went through a couple of revisions with a longhorn and they said it was still too complicated. this was the most basic version they could understand.

turns out a 5 year old could read these instructions and perform this mod for you.

who would have thought? a longhorn has the intelligence of a 5 year old.

gizmoii · 09-29-2004, 04:07 PM

Is this a noticable horsepower gain?

rawze · 09-29-2004, 05:09 PM

i think it has more power than the cai i had. i didn't completely remove the inside pipe - i just cut the top off so the incoming air is directed right at the filter

Truck41 · 09-29-2004, 08:36 PM

I hope you guys are reseting your computers, ten hrs is a sufficient drain. remember that the engine is geting more air sooner than before. my exhaust became throatier after a couple of days. it seems like my ecu will adjust better, when the memory is allowed to start uncontaminated. not good grammer, but you get my drift.

Titan4x4Aggie · 09-29-2004, 08:39 PM

Quote:

Originally Posted by gizmoii

Is this a noticable horsepower gain?

not completely sure, but i think the HP difference between this and a volant / K&N is NOT worth $250. both systems expose the full area of the air filter to the full air stream, and both pull cold air from the fender well.

the only thing you get with the aftermarket systems that is better is a free-er flowing cone filter. but, this comes with a risk of damaging your AFM. not worth it. save the $250 and get a billett grille. you'll get more complements on that, and you know it's working every time you see it

and a dealer would be less likely to try and void your warrenty over this, i'm guessing.

dersheist · 09-30-2004, 12:16 AM

Quote:

Originally Posted by Truck41

I hope you guys are reseting your computers, ten hrs is a sufficient drain. remember that the engine is geting more air sooner than before. my exhaust became throatier after a couple of days. it seems like my ecu will adjust better, when the memory is allowed to start uncontaminated. not good grammer, but you get my drift.

Just for clarification, are you saying unplug the battery for about 10 hours to reset the computer?

FLA-Titan · 09-30-2004, 09:23 AM

Yes. Just leave it off overnight.

dersheist · 09-30-2004, 10:42 AM

Quote:

Originally Posted by FLA-Titan

Yes. Just leave it off overnight.

Any side effects from resetting the computer besides allowing it to accomodate for more initial airflow?

bvstone · 09-30-2004, 10:45 AM

You're not increasing airflow doing this.. what you are doing is increasing the size of the airbox which should help low end torque.

By this I mean by removing part of the snorkle, the volume of the removed piece is the volume of the airbox that you are gaining. Can't hurt. Resetting the computer... that's something like a wives tail IMHO.. the ECU will adjust on it's own.

Titan4x4Aggie · 09-30-2004, 05:46 PM

Quote:

Originally Posted by bvstone

You're not increasing airflow doing this.. what you are doing is increasing the size of the airbox which should help low end torque.

By this I mean by removing part of the snorkle, the volume of the removed piece is the volume of the airbox that you are gaining. Can't hurt. Resetting the computer... that's something like a wives tail IMHO.. the ECU will adjust on it's own.

with the current setup, the air pulled through the snorkel only sees a small area of the lower part of the filter since it is so close. for the air to travel through more of the filter, it would have to make two 90º turns, does not happen. that would take too much force to move the airflow like that. instead, it takes the path of least resistance, which is to flow through a small part of the filter.

by removing the long snorkel, the air can spread out, slow down, and flow through more of the filter, resulting in less resistance and less hp losses.

you can equate it to electrical theory, there V=IR. in the case of flow, P=VR, where p = pressure, v = volumetric flow rate, and r = flow resistance.

just like you decrease electrical resistance with larger wire, increasing filter size will decrease air flow resistance.

P=VR, V=P/R. pressure remains the same (or close to) because the driving pressure is simply the difference between the vacuum inside the engine as teh air is being pulled in and the atmospheric pressure of the air coming in.

that means if resistance decreases (which it does b/c of the bigger flow surface), the flow rate V will increase. this means the engine can pull the air into the chambers easier, saving HP.