Tuesday, September 15, 2020

Street Prepared DIY Air Dam and Front Splitter - Part 1

My factory air dam finally has been damaged to the point where I'll take the time to build parts specifically classed for Street Prepared in SCCA Solo/AutoX:

Passenger side air dam mounts are torn, face is scraped pretty good too...

This will be one of a series of posts on creating a DIY air dam and front splitter. Let's look at the SCCA AutoX Rules, page 102 - Street Prepared Modifications:

"A spoiler/splitter may be added to the front of the car below the bumper. It may not extend rearward beyond the front most part of the front wheel well openings, and may not block normal grille or other openings, or obstruct lights. Splitters may not protrude beyond the bumper. Openings may not be used for the purpose of ducting air to the radiator or oil cooler, but they may allow air to flow through a permitted oil cooler provided no ducting is used. The spoiler may not function as a wing. This allows a vertical air dam/spoiler above a horizontal splitter, but splitter fences or longitudinal vertical members that serve to trap air on top of the splitter by preventing it from flowing around the sides of the car are not allowed."

By using a heavy nut, I made a simple plumb bob to map the outline of the bumper:

The front nose sticks out the most past the OE aero parts just over an inch, the other areas is less than an inch.

Required watching, reading before starting your own project:

Construction Notes:

  • By increasing the size of the air dam and splitter - extra supports will be needed outside of the OE mounting locations.
    • For track cars quad mount points on the front and four more on the back.
    • The RX-8's front most support point are the tow hooks as they connect into the crash bar through the front bumper.
  • In keeping with my class:
    • I cannot make the splitter past the front part of the wheel well opening,
    • Nor can the splitter extend past the bumper,
    • I can duct air into the radiators through the air dam as long as it is vertical and not horizontal.
  • 15/32 in Birch wood is lighter per square foot than Aluminum
  • Custom mounting brackets are required to secure the back sections of the splitter and support extra load form the additional downforce.
    • I bent and cut aluminum strips to size for the rear mounts,
    • Front mounts are cable railing hardware.

After separating the OE air dam from the bumper, I took clamps and fixed the wood to the air dam:

Next, I traced the outline with the air dam and as well from the front bumper using the home made plumb bob to map the outside perimeter of the splitter based on the bumper's outline:

Here is a top down view with the wood clamped in place:
The contour of the bumper is where the extra space is gained across the head lights into the center of the nose.

Next is tracing the mounting holes for the OE splitter:

In the next post I'll show how to add metal supports to the back of the wood for additional durability, as well as fabricating mounts for the splitter and the air dam.

Stay tuned for more!

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