Great thread, again!
For the earlier question about who allows unlimited aerodynamic mods, the TTS,U,R classes in NASA are set up this way. There are some minor restrictions, like no movable surfaces are allowed (and they just added that for 2012. Too bad, because I was contemplating a poor man's DRS). Anyway, a rear diffuser, undertray and side skirts would be class legal for my car, and I am considering adding all three for next year's racing season (in that order).
DIY aero summary of what I have so far:
- 3/8" birch plywood splitter (for some reason 3/8" birch is hard to find here now). DIY fabricated mounts attached to the tow hook attachment points, and Lowe's Racing aluminum turnbuckles attached to holes in the stock bumper. I can stand on it, works great, and it definitely balances out the rear wing.
- 1/8" ABS front air dam. DIY brake duct flanges made from PVC plumbing parts at Lowe's Racing.
- Fully sealed front nose using coroplast. All air flow is forced through the radiator. The car does not overheat on the track in South Texas 100F heat (320 RWHP LS1).
- Oil cooler duct made from coroplast. This made a big difference with oil temperatures versus just having it in the same place with no ducting.
- Rear wing is a NASCAR COT wing. I love it. It is attached to the trunk with aluminum L-brackets and some APR uprights I had from my previous dual-element wing. Since I gutted most of the trunk frame, I reinforced the mounts underneath with form-fitting thermoset structurally anisotropic composite (chopped fiberglass Bondo).
- The fender flares are Autokonexion Version 1 units.
- Hood vents are a Carbontrix hood vent, and side vents are very inexpensive plastic units available at larger boating supply stores.
- No rear window in the hard top yet. I have been holding off to build a fastback type unit and will be totally stealing, er I mean building a homage tribute of lightyear's approach. Like with the ABS air dam, I had been brainstorming this sort of thing, and now that someone else has done it I can see that it looks pretty damn cool and, more importantly, effective for a track car. I need to get with it already and build one.
All of this was tested to 145+ mph (5 Hz GPS logged with Trackmaster) which is the highest speed I have reached so far at the end of the front straight at TWS. Point being, it is all sturdy and it all works.
Total spent, say ~$900 with most of that being the cost of the COT wing, fender flares, and Carbontrix hood vent (impulse buy).
Beating up on TT NARRA Vipers worth a lot more money than my little Miata, priceless.
The splitter with the main supports visible, and the front nose cut off to make way for the ABS air dam.
Closer view of the nose
Sitting on the grid waiting for my TT session at the TWS NARRA race. Holy $^it they required a lot of sponsor stickers.
Yeah, I just passed that Viper
Gratuitous podium shot. Me in second place on the left. Incidentally, first place in the middle is Chris, also in a V8 Miata, very nicely built and tuned by Perryrace at miata.net. Chris broke the TWS NARRA TT-3 class lap record, and spanked a lot of very expensive Vipers in the process. It was a glorious weekend for Miatas, especially considering I was a riff-raff poor-man racer compared to the serious $$$ hardware most of the field showed up with.
Video of my fast lap for the weekend. There were at least two more seconds in the car, but I had been struggling with suspension tuning issues which I figured out too late (to get in some faster lap times). Instructing, driving, and tuning/wrenching as a one-man operation makes for a busy weekend. Whatever, good enough for 2nd place and some free Hoosiers. Ignore the dash speedometer because it is not calibrated correctly.
What is the point of all this information? DIY Aero FTW!