69427

Trying to figure out if I would be improving the aero situation, or worsening it. I've got a bellypan rearward of the splitter, but I keep wondering what adding a 1 1/2 -2" rubber airdam at the front would do. I can't lower the splitter as I'd never get the car up the trailer ramp, but I'd like to keep a bit more air from getting under the car. My concern is the airdam would cause more turbulent air across the bellypan, possibly defeating some of the reason for the airdam or the bellypan.

I appreciate any constructive input.

crimlwC6

I was thinking the same thing this morning. I'm just starting to try and understand aero on my car but I think I've read all the aero posts on this site plus plenty of others. So I'm dangerous enough to sound knowledgeable with no actual experience . Lou from LG and Jason from Katech have responded to a few aero threads with their input which should really be listened to. My understanding is that you can take two approaches: air dam (Nascar) and keep all the air going under the car out or splitter with undertray and move the air under the car as fast as possible and ideally have diffuser (DTM/F1). I have seen very few diffusers on vettes.
If you could do an airdam that would seal the air out and have a small splitter on the front, I think that would be ideal but you'd need an airdam that is made out of something like Tegris because it would need to contact the racing surface at least occasionally, would need to removal to get on trailer, and any off track excursion would be expensive. I really have no idea whether a small airdam would help but maybe we'll get some discussion going.

crimlwC6

Of course if you use an airdam you have to get enough air into the car for cooling, I was assuming you had converted to a front breather.

eogel

I think I have done what you are talking about, but first the disclaimer. I am not an aero knowledgeable person. I read to understand and then experiment with my car. My car is an ’86 raced in NASA ST2. The aero I am describing has just recently been completed and I have no measurable results. The best evidence I have at this time is pictures showing how the bottom of the car is sealed off when on track.

The car has an aero nose and is a front breather. It has no belly pan behind the splitter, and the splitter is not much deeper than where the rubber air dam is mounted.

You still have a trailer loading consideration with the splitter. Although the rubber flexes, if too close to the loading surface, it will tear or hang up on the L shaped bracket that mounts the rubber to the splitter. I do not remove anything to load and unload, but I do have a hydraulic tilting open trailer. I have also loaded it on and off of an enclosed with no problem if done carefully.

If the air dam is effective, it should not be causing turbulent air behind it, the air flow should be minimal to none. My air dam is angled from front center back toward the wheels, routing air hitting it around the front of the car.

I specifically selected rubber so it would flex if it encounters a hard object (curbing). I think it is ¼” thick. It can contact the racing surface and will also wear to the correct level if you made it too long. This allows the down force created by any other aero mods to push the car down with no damage. The better the seal with the racing surface, the more effective it is.

I do not have a real diffuser yet, but I have attempted to route any air under the car out and keep air from coming in from the sides at the rear. I have also fabricated side skirts with rubber on the bottom. The side skirts start along the frame where it goes under the car, inside of the front wheels. The side skirts start well inside of where the air dam stops at the edge of the splitter.

Ed

http://s185.photobucket.com/user/eog...tml?sort=3&o=2
http://s185.photobucket.com/user/eog...tml?sort=3&o=0

VGLNTE1

is this on the c3 in your sig or another car? just curious. If the bottom of the car is flat, the air will flow across it fast, creating some downforce without drag, which is what we all want. Adding a airdam is just going to act like a stock c5 with its rubber crap hanging underneath, unless you are going to bolt on all the way around the front like a nascar type ca, which will create 0 downforce. Are you racing to the point where you need every .0001 off the lap, or for just ***** and giggles? my money would go on the flat bottom with a splitter.

69427

Thanks for your input here guys. I appreciate it.

The car in my avatar is what I'm working on. It's no big secret that in the late 60's the underside of C3s weren't given a lot of design thought regarding aero efficiency. I've made a lot of changes in the car over the years to decrease the performance deficiencies inherent in a 40+ year old car (weight reduction, weight relocation, C4 suspension, coilovers, ZL-1 engine). These changes have certainly helped, but I'm running out of ideas that will help me to reasonably keep up with later Corvettes (and P cars) on track days while still letting me keep the 40+ year old appearance. Hence, I'm shooting for a bit more aero efficiency, hopefully in reduced drag at speed (and any reduction in lift is certainly welcomed) by smoothing out the bottom of the car. I've got about 60% of the undercar smoothed out, and I'm just trying to make a few more steps, hopefully in the right direction.
Regarding engine cooling, C3s are both front and bottom breathers (although both sources are above the splitter due to the front styling of C3s). I've closed off about 70% of the total area so far, and my DeWitts radiator still keeps the engine cool, even on 90+ degree days. I generally block off a bit more each track day to sneak up on the minimum required airflow point, and also have some aluminum panels in the engine compartment to induce the air to flow out the side louvers rather than dump under the car.
That's the basics so far. Any additional input is similarly welcomed.