E30 Cold Air Intake

Since heat shields or cold air intake (CAI) setups are not available for the e30, I decided to make my own. I thought this would nicely complete my "big six" M30 air flow meter swap.

My plan was to cover the right and rear sides of the filter, then use the area in front of the wheel well as the bottom, the fender as the left side and the hood as the top. The front would be open to allow air in from the grille. I also have the left hi-beam out and a screen over the hole, which will also help feed air into the filter box.

I started by cutting up some pieces of cardboard and placing them around the cone air filter, to see how they would best fit. I not only had to make sure the pieces would shield off the filter, but had to figure out a way to mount them. After cutting, taping and bending the cardboard for about 30 minutes, I came up with a design which looked like it would work really well.

The next step was to make some new (beta) cardboard templates out of the existing (alpha) templates. This would allow me to have more solid pieces to work with, and I could use them to check for a proper fit.

I made a few small changes to the beta templates, then decided to make the actual pieces. I went to the hardware store and picked up a 24x36 inch piece of sheet metal, some tin snips, some small self-tapping screws and some small nut/bolt/washer sets.

I traced the cardboard templates onto the sheet metal, then cut it out using the tin snips. I used a stone grinding wheel in a drill press to smooth the edges. The first piece (which will make up the right side) had several bends in the lower portion, to fill in an area that would have been open. Bending the metal over the area in front of the wheel well would also give me a place to secure the bottom of the plate. I placed the piece in a vice, and slowly made the bends by just pushing the metal down with my hand.

For the next 2 bends, I clamped the metal to a piece of flat wood on the bench. The edge of the wood gave me an edge to fold the metal on, giving me a nice straight bend. Once this was done, I checked the fit in the car to make sure it was done correctly. Once I made sure it was ok, I could finish the rest of the piece.

I made a hole for the coolant overflow line to pass through, by drilling several small holes along the line I had marked on the metal with a marker. I then used the tin snips to cut the piece out. Using the stone grinding wheel, I smoothed out the edge of the hole. I finished it up by cutting along one side of some small vacuum hose, and pressing it over the edge. This would keep the metal from cutting into the rubber coolant hose. The last step for this piece was to drill a hole for the front mounting tab. Now I could mount the piece in the car. I used 3 self-tapping screws to secure the bottom of the shield to the area in front of the fender, then bolted the tab in the front, to the front of the car using an existing hole.

With the first piece finished, I could work on the second piece (which will make up the back side). The first step was to make the hole where the flange on the front side of the AFM would pass through the metal shield. I did this by again drilling small holes along the line I had traced, cutting out the remaining portions of metal with the tin snips, then grinding down the edge. Since I did not have enough room to use the vacuum hose around the edge of the metal, I used electrical tape. This will just keep the metal from vibrating on the metal flange of the AFM. I did use vacuum hose along one section of the shield which was cut to fit around another coolant line (which comes out from the bottom of the coolant reservoir). I checked the fit in the car, to make sure the hole was made correctly. The last step was to make a bend along the right side where I will bolt the 2 pieces together. I made the bend by clamping the edge in the vise, then folding the metal over using my hand. I drilled five holes along the edge, then installed the piece in the car. Using the holes as guides, I marked the places in the first piece where I will need to make corresponding holes. I pulled the first piece out, and drilled the five holes.

I installed the pieces and bolted everything tight. I checked to make sure I had proper hood clearance, then lined the top edge with the shield with strips of the vacuum line.

Here is the finished product, with the filter installed:

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