How to Make a Fiberglass Air Box

An air box provides an enclosed container that forces outside air going into a system through the boxs internal assembly. This ensures that the intake air going into a vehicles engine travels through an air filter inside the box, screening out and blocking contaminants. Making a fiberglass air box can be as intricate or as simple as needed. The process follows the same principles as other fiberglass construction, and the details are influenced by how you build the mold.

Instructions

Preparation

1

Plan out with paper and pen the dimensions of your air box. Draw the measurements to scale, matching how the unit will fit in your vehicle.

2

Create a mold shape based on your design by building a frame and surface using wood and foam. Build the wood frame after cutting the pieces appropriately with a saw and connecting them together with nails and a hammer. Glue foam to the frame, and cut the foam to shape with cutting tools.

3

Continue trimming and shaping the mold inside until it forms the shape you want the air box to be on its outside. Spray the final mold surface with nonstick wax to allow the mold to separate later on.

4

Use scissors to cut various pieces of fiberglass cloth to size. Make a pile of them to be readily available when applying the resin. Pour fiberglass resin and hardener into a bucket. Mix the contents with a mixing stick.

Fiberglass

5

Use a paint brush or roller to draw the resin mixture from a paint tray. Apply first layer of resin to the inside of the mold. Press pieces of fiberglass cloth into the resin. Roll them flat with the paint roller to squish out air bubbles. Paint more resin on top.

6

Repeat the process until you apply three to four layers inside the mold. Cover the last cloth layer with more resin. Let it dry for an hour. Restart the layer process again. Continue layering until the fiberglass inside is at least 3/4 inch thick.

7

Let the mold cure and dry for a day. Clean up your materials in the meantime. Use a plastic scraper to separate the fiberglass from the mold.

8

Take the hardened fiberglass to a worktable. Put on a respirator mask. Sand and trim the edges of the box to smooth out bumps and edges with an automated sander. Continue until every surface is smooth. Use a power drill and bore to cut cavities as necessary per your needs.

9

Paint your sanded air box with a primer and finishing spray paint. Follow the same process to create a lid for your air box.