How To: Make your own cold air intake

By: Slater

* Disclaimer
This mod requires the use of simple hand tools, creativity, common sense, and imagination. Read through these instructions carefully BEFORE attempting this install. If you donít understand something, or are not sure how to do some or all of these steps, please consider NOT doing this mod, or else having someone else more knowledgeable do it for you. These instructions are very simple and easy to follow for even a novice, but please do not email me halfway through the install when half your motor is in pieces on the floor and you are totally lost and have no idea what to do next. Remember that I am not responsible for this modification and any damage it causes. You do this fully at your own risk!

The AEM cold air intake is hands-down, the absolute best intake system on the market
period. Dyno result after dyno result proves that this system makes the most power of ANY intake system on the market PERIOD
more than Iceman, Weapon R, RS Akimoto, PRM, etc. There are a number of reasons for this; the main reasons include how the system was engineered overall. AEM "tunes" the system to each application - the length of the overall tubing, the diameter of the tubing, and the minimal number of bends all work together to make this system create the maximum power from your motor. The smaller, 2.5" single-diameter tubing helps increase the velocity of the air flow, and the placement of the air filter ensures that the coldest air possible will be drawn in. This colder, faster air is what allows the AEM CAI (cold-air intake) to make maximum power on Honda and Acura engines.

There are a few problems with the AEM system, however. The first is that itís made of aluminum. Aluminum is lightweight, but is also an excellent conductor of heat. Thermoplastic and silicone would be better, like the Iceman and PRM systems, but steel works as well as aluminum (better in cact) with only a small weight increase over aluminum, plastic, or silicone. The AEM systems are ceramic coated, which helps block heat, but they only ceramic coat the OUTSIDE. Another problem is price
the retail price of an AEM system is $250.

I have found a way to make an AEM-style intake, for 1/4th of the cost. I have not dyno tuned this new intake, but in swapping out my old AEM intake for my version, I can tell you that I have not noticed any power loss whatsoever. In fact, the new system feels stronger than the AEM system did. I will explain the reasons why I think my system makes slightly more power than the AEM system later in the article.

Hereís what youíll need:

The toal cost of the project is about $60 - $70 depnding on shipping prices, the brand of filter you buy, etc.

* Notes:

- First, the tubing. Believe it or not, the tubing is a piece of mandrel-bent tubing from J.C. Whitney! Itís a "180 degree u-bend". I paid $17.98 (received word from a member that the price has gone up to $23.00 + shipping) for mine. Call (312) 431-6102 and order part number 81EH3035N. This single piece of pipe will be used to make the entire CAI system! (The piping is slightly heavier than the aluminum AEM system, but we are only talking about a pound or so and the power gains and price savings from this system more than outweigh the pound you will gain with the steel piping!)

- The rubber pipe clamps can be purchased at any Loweís Home Improvement Store. They are made of durable, flexible, high-temp black rubber, and already have (2) stainless steel clamps integrated into the clamp. Go to the PVC plumbing section, and look for "PVC Pipe Clamps". The ones you need are for 2" PVC pipe.  The clamps cost $4 each, and you will need (4) of them.

- On the filter, you can order K&N filters from just about anywhere. The price varies from $20 - $50 dollars. I paid $30 for mine from Itís a 6" filter with a 3" opening and includes a built-in funnel-ram velocity stack. Other good choices are RS Akimoto filters with both an internal aluminum and built-in velocity stack. You can also order an AEM replacement filter direct from AEM (or any AEM dealer). I do not know the exact price, but it shouldnít be more than $40. The AEM filter will provide the best fit, since they are basically the only company that uses the smaller 2.5" diameter piping instead of the more common 3" piping. With the 3" filters, you will have to use one of the pipe clamps as a step-up adapter, where the AEM filter would bolt right on and fit perfectly.

- As far as the ceramic paint, go to any Auto Zone or Wal-Mart store, and buy "Dupli-Color" brand high-temp engine paint. I would recommend using this brand of paint because it does NOT require the use of primer. This paint is also good stuff because it is actually ceramic-based, which greatly helps block heat. The paint runs about $3 a can and you will need (1) cans. I used "Aluminum" color because it matches the AEM color perfectly. You can use any color you want though.

- The grommet and hoses will be used to make the crankcase vent system. You can buy the parts at Loweís when you are buying the PCV pipe clamps. I got the hoses in the plumbing section, and the grommet in the hardware section. The plastic hose is a milky white and is hard plastic. You only need about 3" of it, but you have to buy it by the foot. The vinyl tubing is clear, although any color will work. You will need about 1 foot of tubing (12").

Thatís the end of the notes. Letís move on to the install.

For shortness sake, I will assume that you have already removed the bumper and all of the stock airbox components - the upper and lower resonators, the "airbox" located in the bumper, and also the upper rubber hose that goes to the throttle body. If you do not have these components removed, or do not know how, I would recommend checking the following link for instructions:


Now, take your muffler pipe and clean it up using soap and water. Mine was covered in grease used for lubrication during the mandrel-bending process. Once it is cleaned off, make sure itís dry. The first step is to cut the pipe. The top bend is the easiest to do first (i.e. the one that connects to the throttle body).

You can see from the following picture that the angle matches the stock intake angle perfectly. You can use the stock upper piece as a rough guide for making the cut.

I laid the pipe up against the throttle body, and eyeballed the proper angle that the pipe needed to be cut at. Sorry, I donít have an exact degree for you, but the object is to line up the straight part of the pipe with the hole that goes from the engine bay down into the bumper (where you removed the resonator pieces from).

Youíre going to have to use your imagination and a little creativity here, but itís not hard. See the following picture:

Use a hacksaw or cutting disc to make the cut (make sure itís straight!!). When finished cutting, clean up any rough or sharp edges with the metal file and sandpaper.

Now double-check everything by installing the first rubber pipe fitting onto the throttle body. Itís a VERY tight fit, so it will help to lubricate the fitting using a rubber friendly lubricant like silicone grease or even a little bar soap (wet your fingertip and rub a bar of soap). You will have to wrestle it on, but it does fit, as in the following picture:

Once you have the fitting on, insert the pipe and clamp it down. Make sure the straight part of the pipe goes perfectly towards the opening to the bumper where the resonator was. One thing to note here. Those worried about hydrolock and water, can convert their CAI into a "dry" system by simply bolting the filter onto this short piece of pipe. This is useful during rainy or winter months. See the picture below:

Once you are satisfied with the first piece, itís time to complete the rest of the system. Once again, imagination and creativity come into play here as I cannot tell you the exact cuts to make. I had to redo a few of the cuts to get everything to line up. Remember to clean up all of the edges with the metal file and sandpaper so you donít cut yourself and/or damage the rubber pipe fittings.

Use the following pictures as a guide on where to make the rest of the cuts:

As you make each cut, keep assembling and test fitting the entire intake system. Attach the second pipe to the first pipe still attached to the throttle body, and make sure the second pipe curves down into the bumper hole. Then attach the third pipe to the second pipe and make sure it makes a curve in the opposite direction. You will have to attach the third pipe from inside the lower bumper opening.

After you rearrange the pipes, the entire system should look roughly like the following pictures:

You can assemble the whole system outside of the car using the fittings and the filter. It should look like the following pictures:

(The AEM air filter and it's orange fitting was used during the prototype process...)

Once the system looks like the pictures, and you have test fitted everything, itís time to finish the job.


This step involves making the crankcase vent that goes from the intake system to the valve cover (i.e. crankcase). You need to do this part
it cannot be left out! Anyways, all you will be doing is drilling a 3/8" hole into the upper (i.e. first) intake pipe. Look at the stock piece (and also the pictures) to see about where the hose needs to go:

It will be easiest to start with a small drill bit and move up to 3/8". Make sure you make the hole facing the valve cover connection! Once you have drilled the 3/8" hole, insert the 3/8" rubber grommet. Then cut a 3" or so piece of the milky white 3/8" OD plastic tube, and insert it into the grommet. Make SURE it is a very tight fit, basically airtight. It might even be so tight that you need to lubricate the tube to insert it into the grommet. Insert the tube so that about 1" is inside the pipe itself, and 2" is outside of the pipe. Once the tube is in the pipe, attach the 5/8" OD (3/8" ID) tube OVER the milky white plastic tube, and attach the other end to the vent on the valve cover. You may need to shorten the length of tubing to fit. Make sure itís not stretched too tight, but not too much slack either. Also, make sure the tubing isnít kinked - this will restrict arflow.

See the following drawing for what the complete system should look like:

Once the tubing system is complete, remove the tubing pieces and the grommet.

* Note: If you are making this system for an OBD-II car (i.e. 1996+), you will need to make a place for the intake air temperature sensor. See the additional notes section at the end of the article for more information before continuing!

You're almost done...the next step is to paint the system.

Get everything cleaned up again using soap and water, or a good engine degreaser or cleaner. Finally, rub it all down with isopropyl alcohol to remove any hand and finger oil. Once you have done so, itís time to paint the system. This is a VERY important step. Why? Well, the piping is made of plain mild steel, which rusts. The good news is that this piping has been aluminized because it was originally designed for use as exhaust piping. This is to our advantage, because the aluminization will help fight off rust caused by rain moisture and winter salt. However, the edges are exposed steel, and will rust. Also, the ceramic-based paint will help block most of the underhood engine heat, and painting the inside of the pipe will help to smooth the interior. This will speed up the airflow which is a good thing.


Paint the inside of the piping first, using light coats. You will have to be creative here, and shoot the inside of the pipe from both ends to ensure the entire inside of the pipe is covered with paint. Make sure you keep moving the can, and donít spray too heavily, which will cause BAD paint runs and also reduce the overall inside diameter of the piping. I painted the inside of my system with a total of about 3 light coats of white.

Let it dry for a few hours, and come back and reclean the outside of the pipe with the isopropyl alcohol to remove any hand or finger oils. Then carefully paint the outside of the pipe using light coats. You will have to flip the pieces over to make sure you cover the entire pipe, or you can just suspend the pipe from a piece of string (allowing you to paint the entire piece of piece at once without flipping it over to do the other side.) I used about 4 coats of paint on the outside.

You will be able to handle the pipe after a few hours or drying, but I would HIGHLY recommend even letting the paint dry overnight, as it takes some time to cure. Follow the instructions on the can of paint for the exact details.

Once the system is completely dry, it time to finish up. You will start by CLEANING THE  INSIDE OF THE PIPING!!! Anything inside of the piping (i.e. dust, metal shavings, loose paint, etc.) will get SUCKED RIGHT INTO YOUR ENGINE when you start the car! This is BAD if you didnít guess. The easiest way to do it is to run a medium sized towel into the pipe, and pull it through the other end. The towel will pull any loose particles with it and leave the inside of the pipe clean and ready to go.

Once the piping has been cleaned out, reinstall the grommets and insert the milky white 3/8" OD plastic tube. Then assemble the intake system and install it. I had to install the upper two pieces first, and then bolt the third piece and filter on from underneath the bumper opening. See picture:

(The filter used here is a "funnel ram filter" used during the prototype process...)

Hang on, youíre almost done!! The completed system should look like this picture:

(The filter used here is the AEM filter again used during the prototype process...)

If your system looks like the pictur above, you did it right! If not, you must have missed a few steps ;0)

Donít forget to hook up the vinyl tube that goes from the intake pipe to the valve cover vent!!

Finally, put your bumper back on, clean up, and go out for a test drive! You should feel a SIGNIFICANT difference in power across the entire power band. I will dyno my car soon with the new system and report the results. If anyone has a chance to do so in the mean time, I would love to see the exact figures.

- Slater