DIY Network

Custom Air Intake: Fabricate and Install the New Air-Box Mitsubishi Eclipse--Engine Upgrade, Part 2 of 3 From "Tricked Out" episode DTRK-305

The performance air-intake is housed in a custom-built isolation box.

In this project, Andrew Totolos installs a custom air intake system and ignition upgrades on a 1999 Mitsubishi Eclipse RS. Thus far he has removed the factory airbox, then he custom-built and installed a short-RAM intake system on the elcipse.

Now that the factory air-box has been removed, the next phase of the project will be to build and install a custom isolation box for the cold-air intake.

All of these modifications, along with ignition enhancements that will be added later, will help to increase the power and fuel economy of the Eclipse.

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The isolation box is fashioned from sheet aluminum. Cardboard is used to create a template for cutting the aluminum for proper fit.

Fabricating the Isolation Box

Materials/tools used in this portion of the project:

measuring tape
piece of cardboard
utility knife
heavy-duty tape
hole saw
aluminum sheet
sheet metal screws
self-tapping screws
standard shop tools
drill and drill bits
marker
safety goggles and gloves

Before beginning construction of the isolation box, it's important to take some measurements. In the Eclipse, the box should be no taller than 11 inches at the intake side to provide adequate hood clearance (figure A).

• Start with a strip of cardboard cut to the box height and about three feet long. Estimate the location of the corners, then score the corners of the cardboard template and fold it into shape.

• Do the same for the second bend (figure B). Continue estimating and scoring the bends until you have a completed shape.

  Figure A

  Figure B

  
  

• When you're satisfied with the fit, cut the excess cardboard from the template and check the fit. Use heavy-duty tape to secure the ends of the template together, along with a piece across the top to hold the correct angles (figure C).

• Next, remove the filter and the first pipe bend and set the template into position (figure D).

  Figure C

  Figure D

  
  

  	Figure E
  	Figure F

• Then press the template against the mounting plate to mark the factory inlet air tube location. Handhold a hole saw bit to carefully cut through the cardboard at the marked location.

• Next, start the mounting screws back into the mounting plate and tighten them down below the surface of the intake tube flange. Then press the template against the screws to make more indentions on the cardboard. Punch out the indentions with a screwdriver (figure E).

• Once the mounting side of the template is complete use a screw or two to temporarily hold it in place. Use a hole saw bit to mark the outlet side hole in the rear of the box.

• Take the box to a workbench to finish the second large hole.

• Reinstall the template in the car and replace the air filter to check the final fit (figure F).
  

  	Figure G
  	Figure H

• The actual box will be made with a sheet of 2/1000-inch-thick aluminum. When the template is complete, place it carefully onto one corner of the aluminum sheet and mark the depth (figure G).

• Use a square to mark a line all the way across the sheet. Before you lay the box down, move in an inch to allow for a mounting tab and mark all of the side lengths by carefully rolling it along the sheet.

• Use the square again to mark all the corner bends, and then align the template on the aluminum to mark the holes. Turn it onto its bottom to trace out the lower cover (figure H). The lines don't have to be exact because they get extended by one inch to provide for mounting tabs.
  

  	Figure J
  	Figure I

• In order for the tabs to fold correctly, you'll also need to mark right angles up from each corner of the bottom plate to the edge of each tab.

• When all of the marking is complete, use a straightedge to score the aluminum along the cut lines with a sharp utility knife. Make about three passes with medium pressure to reach the proper depth.

• Put on some gloves and glasses and bend the aluminum along the score lines at the edge of your bench, and peel it apart along the cut. A pair of needle-nose pliers will help you wiggle out the small sections.

• Once the main section is cut out, clamp it to a piece of wood and drill out the holes (figures I and J). Use a three-inch hole saw for the inlet and outlet ports, and a standard bit for the three mounting holes along the inlet side.
  

• Once you get everything cut out you can make the bends. The easiest way to get 90-degree bends is to clamp the metal between two pieces of wood along the bend line. Start the bend by hand and use a mallet to tap the bend into its final shape (figure K).

• Repeat the process to make the remaining bends.

Figure K

Figure L

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