Another post worth bringing over here:
http://forums.corvetteforum.com/autoc ... unnel.html#post1569403188

[QUOTE]SuperL98;
Corvette Fever (May 2009) has an interesting article this month on Aerodynamics.
They took Corvettes, from each generation, and tested them in the AeroDyn wind tunnel (Mooresville, North Carolina).
http://www.a2wt.com



I don’t think I can “legally” post the whole article, but here are the graph results.
Data seams to be taken at 85 mph, and “Passengers” means they placed weight in the seats.




I put their CDA, Lift/Drag Ratio, and % Front Lift, into a spreadsheet and calculated values up to 200 mph.
Just did the base model coupes, with passengers.
Keep in mind this is just Aerodynamic Drag (from the data) and no rolling resistance.



And front and rear lift, again from their data.




Interesting stuff, if the data is believable?
The C5 has the lowest drag.
The C4 & C3 have the lowest rear Lift, even lower than the C6?
Look how high the C4 drag coeff is 0.371 ?

Anyway, hope this is interesting......

Yes, the early cars are:

C1 is a 62
C2 is a 63 Split Window
C3 is a 70
C4 is a 90 ZR1

AeroDyn has a few picture and a video of a C6 in the tunnel, on their web page.






http://www.youtube.com/watch?v=aduap_AS5j8
http://www.youtube.com/watch?v=aduap_AS5j8
http://www.youtube.com/watch?v=shcms4YnOh8

;)[/QUOTE]

Wow.

There's a good chance their test facility is more up to date than whatever GM used back in 83.

I wonder how repeatable that stuff is with one wind tunnel, or at different locations.

Looks like the C4 does best with a fat girl inside. Did well also on the lift numbers. How many times have you heard that b.s. about C4s generating so much lift at speed? Is extrapolating that to 150 mph even valid? I'm not so sure.

The C5Z06 did pretty bad compared to the base model. Must be the abrupt roofline.

I remember reading in All Corvettes are Red (ACAR) that Hill wanted his guys to shoot for .32 or .33 for Cd on the C5 - it looks like they got pretty darn close.

There was one passage in that book that always puzzled me. In the early aero testing of the C5 body, they (somehow) mated it to a C4 chassis since they did not have a C5 version ready at the time. One of the aero guys was was quoted as saying the C4 had a very "dirty" undercarriage compared to the C5.

If I remember correctly with the C5/4 hybrid, the Cd was .35-.36 or something and it dropped to the above #s when they got the production chassis tested.

Would there be any benefit to running a lower tray on our cars like many of the other modern sports cars? Would it drop the Cd? What difference would that make in driving characteristics?

Running a belly pan is a great way of deducing drag, which is why there are rules against it.

If you really want to do it, you need to watch heat build up.
Which is something C5/6's have a problem with.

By "rules" I assume you mean racing class rules... hopefully not DOT/legal rules against it.

Do the C5/6s run with belly pans? I've never had the chance to peek under one in stock form.

It would also be nice to have a sacrificial piece to take the hits from the scraping and occasional piece of road debris.

Hmm... this might make an interesting little project.

EDIT:

I remember reading that the GT-R runs a belly pan in some form. I guess they felt it helps.

C5/6's don't run bellypans but they are much flatter underneath in general than a C4.

Unless your C4's really lowered, it shouldn't be scraping that much. Not sure if you mean a bellypan or just rub strips by "sacrificial piece".
We do it on the formula cars all the time but the ride height of the bellypan is only 25mm.

I saw that article and really enjoyed it. I was hoping they would compare a chrome bumper C3 to a rubber bumper C3. Seems to me the ride height was lowered a bit and the nose of the later C3s starts a little lower which might help a lot. I would also like to see how the tunnel back glass improved things over the sugar scoop rear window.

Quote:

I have a Vert so the X-brace is my rub strip. My car is lowered with the usual lowering wedges and bolts but there are quite a few poorly designed speed bumps and driveway entrances around here.

I am interested in seeing how the aero would be improved by a pan. It seems to be a popular addition to some of the modern sports cars. For my street car it is probably pointless but it sounds like a fun project to play with.

Pointless?, Don't know but probably not measureable, but not pointless if you like to play with stuff.

Unless your x brace is wearing thru, attaching rub strips will just make it lower.

The bellypans on modern openwheel racecars are aaaaaaaaaa plywood.

I want to try these types of skirts out.

http://forums.corvetteforum.com/c3-te ... s-lets-compare-notes.html

[img]http://members.cox.net/keiferpkr/Tijuana%20Grand%20Prix%202008%20(2).jpg[/img]

[img]http://members.cox.net/keiferpkr/Tijuana%20Grand%20Prix%202%20(2).jpg[/img]

I know this is an old thread, but I'm gathering this information to feed into a dyno app and I'm still looking for some kind of data on rolling resistance. Anybody found that information anywhere for the C4?

This help any?

[IMG]http://i119.photobucket.com/albums/o130/Aardwolfki/aerobook.jpg[/IMG]

Actually, we did cover this. Corvette Chat > C4 gets dissed on drag

Well I like having that informatinon here, but I'm still scratching my head on rolling resistance. How do you figure that one out? That is a measure of the drag on bearings,tires etc that?

how good are you @ math?

http://www.tut.fi/plastics/tyreschool ... _8/hypertext_2/2/2_2.html

I haven't had an opportunity to examine one, but the c4 ZR1 rocker panels look more "skirt like" than than std. ones. I wonder if they could be fitted to a std. model.