EXTERNAL AERODYNAMICS

[69427]

Lots of interesting items being shown and discussed. I'm enjoying this thread.
While I'm trying to figure a robust enough design for the cowl area aero flow spoiler, I've added a couple more feet of undertray to the car (about four feet total back from the Pace Car spoiler) and looking at extending the front air dam down another couple inches. Due to the long nose on a C3, a splitter shelf has to be awful damn forward to not just trap air between it and the higher bumper area, so I don't currently think extending the Pace Car spoiler horizontal surface further forward is going to be a good ROI of time and material for this car. The lower height of the air dam should hopefully reduce the amount of air entering the bottom of the car, helping cornering traction, and particularly front tire grip during braking. I reduced the front suspension anti-dive percentage a few years ago when I read about compliance issues with high amounts of anti-dive. I'm comfortable with the current level of dive during braking, and I guess I'll see if anything now scrapes the pavement.
I'm now looking at directing whatever air I can from under the bellypan/engine out to some vents in the under-door mouldings. I'm still in the design phase, trying to come up with something that won't accidentally end up trapping air in the area as well.
I hate adding any weight to the car, so I'm going at all this pretty slowly at the moment.

 

[phantomjock]

"...splitter shelf has to be awful damn forward to not just trap air between it and the higher bumper area...

Fastening an airdam could be useful, but require some mods to the Pace Car Spoiler. Maybe 'glass in a lip to blind fasten to?
I could be way-off here - sold the Pace Car Spoiler over 15 years ago. so have no real-world data to work from. But I recall the lower lip was substantial(?).
With some thought could maybe be removable for DD?

Cheers - Jim

 

[mfain]

This may be a little hard to explain, but here is what I would suggest. Add brackets to the frame behind the front fascia to support the splitter, Then attach the air dam (really a filler panel in this case) to the bottom of the spoiler but do not attach it to the splitter as a supporting member. Instead, add upward tabs to the top of the splitter behind the air dam to prevent the air dam from pushing back. This "support could be a simple piece of aluminum angle formed to the shape of the back of the air dam.. If you hit something with the splitter, or if it pulls down any with the aero downforce, it won't put stress on the air dam or spoiler. I did this with my C-1. The spoiler support is fairly substantial since it supports both the splitter and the front of the undertray, but it only weighs 6#. In the first photo you can see the splitter/undertray support structure. It is bolted to the frame, and the undertray then bolts up into the structure using countersunk bolts. Then the air dam is added - it bolts to the body behind the bumperettes and to a couple of aluminum brackets inside the center cooling duct. Finally, a CF filler panel - much like you show above as an air dam - fills the gap between the air dam and the splitter. It bolts to the bottom of the air dam, but is not secured to the splitter/undertray. Hope this makes sense.

 

[phantomjock]

Pappy good fill. AND, good example on the C1. I'll use some of that on mine too.
That 6# structure - you doing your own TiG? I need to add that to my bag...
The Airdam on the C1 is exactly what I was trying to 'splain.

Came across an old pic that might show how to on a C-3:


The piece in the lowest segment could be "worked" and supported to be the gap filler.

Cheers - Jim