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Devil's Advocate
8,224 Posts
Discussion Starter #1 (Edited)
How to make your own CAI and save hundreds of dollars in the process!

Why you should replace your OEM Air Intake:
Your stock original equipment manufacturer air intake restricts airflow by using resonators to quiet the sound of the air being sucked into the engine. By replacing your resonators and paper filter elements with straight pipes and a high flow filter you can increase the amount of air going into your engine and increase its effientcy, giving you greater horsepower, torque, and even boost your fuel mileage. It is the single most cost effective modification you can make to your vehicle and greater improves the gains you’ll get later from future modifications made to your engine. Another added bonus is that the filters last much longer than a standard paper filter, requiring just a simple cleaning periodically. The problem though is that to buy this simple upgrade can cost several hundred dollars. By making it yourself you can save the money and have the personal pride that comes along with it and it still doesn’t void your factory warranty.

Approximate Cost:
$65 (Savings of about $300)

Approximate Time Needed:
1-2 hours

Approximate Difficulty:

*These particular instructions and parts/tools list were based upon a 2005 Dodge Dakota Quad Cab ST 4x2 w/ 3.7L Auto. However these instructions can be easily and minor tweaked to work on any dodge truck or suv and many other vehicles.

Parts you’ll need:
Universal Cone Air Filter w/ 3.5” Flange & Hose clamp
Crankcase vent filter w/ 1” flange & Hose clamp
3" x 4" Flexible Coupling w/ 2 3” Hose Clamps
3”x 1’ schedule 40 PVC pipe
2 3” schedule 40 PVC 90 degree bends w/ one male and one female end
4 Self Drilling ¾ “Phillips head sheet metal screws
Insulating high heat paint OR wrap

For optional “Ram air” upgrade:
3” Flexible plastic pipe
Zip Ties

Tools you’ll need:
Flat head and Phillips Screwdrivers
Power drill w/ ½“ drill bit
Socket set
Utility knife
Insulating high heat paint or wrap
Sandpaper – about 300 grit
Masking tape

Step by Step Instructions:
First you should always start with a clean workspace where there is shade, a hard, flat surface to work on, and easy accessibly to a power source and tools as needed. Not everyone, myself included, has a garage or we have garages that can still fit a vehicle because of all the other junk! Next make sure the vehicle is off and that the engine is not hot. Pop the hood and disconnect the battery with a socket wrench. I recommend doing this anytime you make any modification that has to do with the engine or the electrical systems. Then disconnect the intake air temperature sensor and pull the crankcase ventilator hose off of the stock airbox. Next remove your old restrictive stock air intake by removing the hose clamps and the nuts and pulling the pieces apart. Place all the parts you remove to the side for cleaning and storage later. I never recommend getting rid of your stock parts, just in case later down the road if something comes up. Once everything is out that is coming out, take plastic bags and masking tape and seal up the crankcase vent hose, throttle body, and temperature sensor so that you can clean down where the old airbox had been. Use water sparingly around electrical components in the engine bay. A simple carwash detergent and sponge is sufficient but if there is any extra tough dirt and grease, dilute some degreaser with water and spray the offending areas. Lightly rinse and dry the area when you’re done. If you have a blower or shop vacuum with a reverse switch it will make this process much easier and faster than a towel and air dry. Now you can remove the plastic bags and tape that you just placed.

Now you can begin mocking up you new cold air intake! Take your piece of straight 3” schedule forty PVC and make a clean, even cut twelve from the end of the pipe. Masking tape really helps to make an even cut if you don’t have a table saw or a chop saw, just mark your measurement and then place the tape flat against the pipe and wrap it around, insuring that there is no wrinkles and that it stays straight, if it is, the ends should meet up perfectly. Make sure to clean up the edges afterward with some sandpaper. Place the 90 degree bends on either end of the pipe part way and take it over to your engine bay. Hold one end up to the throttle body and adjust the other end so that it faces down and toward the front of the vehicle and mark the angle of the pipe so that you can realign them later. Set this aside for a moment and take that flexible pipe joint into your hands. Now it should be about four inches long, of which about two will fit over the ninety degree pipe bend and about one inch over the throttle body. This leaves you about an inch to place your air intake temperature sensor. It’s just over a half inch wide so measure one and a half inches from the end of the flex joint and take your power drill and half inch drill bit and drill a hole through the flexible pipe joint. Clean up the hole and then take you sensor and work it through the hole up just past the blue O-ring. It should fit tight enough not to need any glue or such to hold it in place. Now put this over the the end of your intake that is to join up to the throttle body so that the sensor faces away from the rest of the intake tube. It should face toward the driver’s side once installed. Clamp it down with one of the hose clamps it came with. Next take your new universal high flow air filter with a three and a half inch flange and put it over the opposite end of the pipe, but be careful not to over tighten it or it will just come free anyways. Now test fit your new intake to your throttle body and make any nessacary adjustments. Go back to your workspace and place the PVC pieces tightly together and screw them to one another with your ¾“ self drilling sheet metal screws. Make sure to clean away any bits of PVC out from inside the intake, you wouldn’t want that to go into your engine now would you!? Place the whole assembly to the side for paint/wrapping. Now take that tiny little breather filter you bought and fit it over your crankcase ventilator hose and use the provided hose clamp to secure it in place. Now go to the front of your truck and look at those black flaps on either side of your radiator. Take a pair of pliers and remove the little tabs and rip out the flaps on both the front and back of the radiator support on the passenger side of the engine bay to create a less restricted path for your air to flow to the new filter through the grille.

Now if you have a base model truck like I do and would like more cold air flow directed toward the filter than you can chose to do this optional “Ram air” modification. Take the flexible plastic sewer pipe type tube and place it through the hole from behind the headlight where the old factory intake got it’s air from. Now take your utility knife or a dremel if you have one and cut out the fake foglight bezel in the front bumper cover. It’s easier to do this with it removed but it’s not required. If you chose to remove it just unscrew the three screws from the inside front of both front wheel wells and the three from up top right where the grille surround meets the bumper cover. Once the bezel is cut out, place the other end of the flexible pipe to the backside of the foglight mount after punching a few holes through it so that you may use zip ties to hold it to the foglight mount. This will now work much like a hood scoop to deliver cold outside air to your filter at high speed, a form of cheap forced induction.

Now back to the Intake tube itself. Make sure there is no dirt or other debris in the tube, clean with water only if necessary and completely dry. You then need to choose whether you’re going to paint it or if you’re going to wrap it. Wrapping it is considerably easier but paint looks better. If you chose to wrap it, purchase an adhesive backed header wrap or similar and wrap it tightly around the pipe, putting on several layers and making sure to smooth out the wrinkles. If you decide to paint, purchase some insulating high temperature tolerant paint, such as header paint, engine enamel, or similar. A good paint will be like a ceramic paint. Take your marker and trace on the pipe at the base of the flanges on either end. Then remove the flexible joint and the filter and tape off the ends where you marked them. Make sure you sand the pipe before and after each coat except the final coats of the color and clear. Start with a primer, then apply your desired base color, and then finally a clear coat. Several layers of each may be necessary, just follow the directions on the can. I recommend not using a paint that requires curing further than an air dry over night and sun bake.

Once you new cold air intake has been painted/wrapped and reinstalled, check to make sure all the screws are properly torque down and that you’ve reconnected the temperature sensor. Before you reconnect the battery, take your keys, put them in the ignition and turn it forward to the on position but don’t attempt to crank it up, just enough so the air and the radio would come on if it were connected. Now turn the key back to the off position and remove your keys from the ignition. Reconnect the battery and give the engine bay a once over to check for any tools or hardware you’ve left sitting in there but don’t close the hood quite yet. Also make sure you clean up any mess you’ve made before the wife gets on ya! Stand halfway inside the cab of your truck and turn off the A/C and the radio. Then turn the ignition over and watch the intake as you do it. Just look around for anything out of place. Your new intake will make a somewhat loud sucking sound but that is completely normal. Run the vehicle more modestly over the next couple days while the engine computer learns to compensate for the added cfm coming through the throttle body. It’s possible that the check engine light may come on, especially if you didn’t reconnect the sensor before starting the truck or if you didn’t disconnect the battery during the insulation. Just go to your local auto parts store to have them read the code for you. It will most likely be P0113 which is air intake temperature sensor high voltage which is caused by unplugging the sensor to install your new intake. They can clear if for you and you should have no problems. Once the computer catches up with the learning curb you can realistically expect gains of about 10 hp, 25 ft. lbs. tq, and around 1 mpg better on average as well as a noticeable quicker throttle response, plus your engine bay will look nicer too! Doing other modifications such as a free flowing exhaust or a performance chip will further these gains.

Feel free to share this article with others but please give credit where credit is due. I was not the first to do this mod but I did take the time to take pictures and write this. I would personally like to thank the staff at and for creating such great informative and fun sites, I’d also like to think the staff at such stores as Advance Auto Parts, Auto Zone, and Lowes for helping me and I’d like to think my best friend jerod who is almost always willing to help me on these little projects as we both teach ourselves to take care and have fun with our vehicles, whether it’s by taking 2 hours to change our own oil for the first time or by having a copilot while I’m driving like an idiot, thanks to all of you! Have fun, drive safe, and remember that your vehicle is more than just your transportation around town, it’s an expression of you, an art, it’s like a good dog; take good care of it and it will take care of you!
-Charles Swartz (05DodgeDakota):rck::gr_patrio

P.S. I got pictures to upload later if yall like the article itself.
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