most of us have beaten the aerodynamics question like an iraqi kid in prison but i had one more thought. i took the vette out last night and it's become glaringly obvious just how low the front end is now. i recently installed a new air dam that sticks down even lower than the original. all in all, i have about 3.5 inches of clearance from the strip to pavement.
we all know how 'dirty' the bottom of the c-3 is. now assuming we have a average ground clearance of, say, 5" at any given point, but at the leading edge of the front end we have an air dam that has only 2-3" of ground clearance, how much of a factor does the actual clearance and the 'cleanliness' of the bottom of the car play at that point? at some point, would the underside of the car even be relevant anymore? i'm pretty sure that if we outfitted a c-3 with a skirt all the way around the bottom with only .5" of clearance, the underside would be virtually irrelevant. obviously, this is not practical even if you wanted to. so now we have to take the variables we can apply and see which ones give the greatest benifit. so if we put a skirt all the way around the car and maintain about 3" of clearance, what impact would that have? if we just had the air dam in front (like i do currently) what would that do? i figure i probably suck in alot of turbulent air underneath the car aft of the air dam essentially negating much of the benifit but i'm just looking to get opinions. if a skirt around the entire car with a 3" clearance would improve speed and stability, i might just try it next time i go out to buttonwillow or something.
just some late night food for thought. can anyone tell i'm up past my bedtime? :D :yawn:

 

From what I've been able to gather, an air dam like you have combined with a rake of 1" back to front is great for the street.

Just to clarify, the underbody just behind the front wheels should be approximately 1" lower than the underbody just forward of the rear wheels. (I hope I'm explaining this right)

 

I think the air dam helps for drag and aero purposes since it prevents air from hitting dirty underside parts. But for aero, the pressure on top is always less than the underside, thats why cars are being "pulled up" at high speed and the dam helps keep nose down it seems. Also spoilers at back end keeps back down against lifting. The less air rushing under the car should mean less lifting. My .02.

 

wow, this is way to technical for me

 

FWIW, my 88 T/A has small side skirts. They only hang down about 2" from the rocker panel. I don't know how effective they are being made of stiff rubber/plastic. I don't think GM would spend the money on them if there wasn't some benefit.

 

The front air dam serves 2 purposes.

1. it helps force air up into the radiator for better cooling.

2. It creates a low air pressure area under the vette to help draw out the hot motor compartment air.

A skirt all the way around, like the GT cars use, also helps to hold the car to the ground. But these cars almost always use a belly pan. to maintain the low pressure area. If you wanted to go this route, and see any benifit from it, you would beed to install a belly pan, and find an alternate exit (out the side) for the hot motor compartment air.

 

Desertdog,
do the NASCAR racers use the "belly pan". I don't recally anything about it.

Clutch, I would'nt think the skirt would help you so much in road racing, unless you carry a lot of serous speed. The tracks where i run, max speed is around 100 - 120 on straight aways and only there for a few seconds before you are hard on the brake.

 

turtlevette: Nascar does not allow the use of a belly pan anywhere under the car. They even have an oil pan size rule as some builders where making the oil pan extremely large to act as a belly pan.

Clutchdust:

First I will give some basics on areodynamics. As I will use very general terms I might not be 100% accurate but will be easier to understand the concept than if I get too technical.

Lift/Downforce and drag are two entirely different forces They work in conjuction with each other. Reducing drag will gererally have little effect on downforce but increasing downforce will generally increase drag.

Drag is the result of air becoming turbulent as it passes over and around an object such as crossmembers, exhaust pipes, suspension parts and brackets. Drag can be reduced by moving an object out of the air stream or limiting the amount of air passing over and around an object. By running a lower front spoiler you will limit the amount of air passing under the car (dirty areodynamically).


To explain downforce I first have to expain a few basic physics of air movement.
The faster air is moving the less pressure it has.
In reverse, the slower moving air is the more presure it has.
Increase the mass of air in the same space and the air will move slower, creating higher pressure.
In reverse, decrease the amount of air in the same space and it will move faster creating lower pressure.

Now you say, how does all this effect our car. :crazy:


If two molecules of air hit the nose of your Corvette at exactly the same time, one going under it and one going over it, those same two molecules will try to meet back together at the same time at the rear of the car (not 100% accurate but used to clarify). If the distance the molecule going under the car (m1) has to travel is longer than the distance the molecule going over the car(m2) has to travel than m1 will have to travel faster than m2 thus creating low pressure underneath (faster air) and high pressure on top (slow air) with the end result being increased downforce.

As you create a low pressure area under the car from a lower front spoiler than air that is traveling along the side of the car will try to "spill under" the car increasing the amount of air that is there. This will slow the air down, there by decreasing the low pressure area. If you put on side skirts then the air from the sides can not spill under the car and will maximize the low pressure area under the car increasing overall downforce.

Sideskirts also have an effect while turning. They increase the overall surface area of the side of the car during turning (yaw) which helps to keep the car going straight so the car can be driven into the corner harder before it will try to oversteer (spinout).


But then again, maybe I am just rambling on and I am not right! :lolg: