aero stuff

[Damn True]

Thats it! we need to have an open windtunnel day and sort all this out. Who has one in there Garage we can use? I understand very little about aerodynamics other than what I read in that hotrod art. read it and you will know as much as I do.The point of my work was mostly for looks, without screwing up the handling to much, and to get maybe a little benifit from it. I dont have a roadcorse here so I really only drive on the street. :3gears:

There are a couple of ways to test the efficacy of your splitter.

The easiest, but least accurate would be the following.
Have a PASSENGER in a second car running next to yours take a photo of the front wheel arch at 40, 60 and 80mph. Then repeat the process with the splitter installed. Then compare the height of the wheel arch relative to the rim in the two sets of photos. If it works it should be reducing front end lift (it probably won't completely eliminate it).

The other method, more complex but more precise, would be to employ a pair of linear potentiometers attached between the lower control arm and the frame. You'd connect the potentiometers to Fluke meter and measure the output both with and without the splitter at various speeds.

The article below will give you an idea of how profound the front end lift is on these cars, nearly 200lbs worth at 85mph. Minimizing or eliminating it could net some significant gains in handling.
http://www.yearone.com/enthusiast/re...8-21camaro.pdf

[Damn True]

BTW, you do have a track in Utah:

http://www.millermotorsportspark.com/

There's Parumph NV...though a bit of a haul.

[David Pozzi]

True, nice article. I have the original Car Life article it was based on.
Further improvement can be found if you lower the front of the car, also stiffer springs reduce front end lift a lot. The soft stock coils allow the front to rise and that generates more lift, - a repeating cycle.

Reducing air entry through the grille area would help a lot, because the Camaro has a huge opening.

Watch the NASCAR rooftop cameras, the hood is being sucked down at times from the lower pressure under the hood.

Here's a good aero article:
http://www.circletrack.com/techarticles/0304_aero/

[vanzuuk1]

David How do you decide how much rake? , I was going to shoot for about an inch with a 3/4 full gas tank.

My dodge used to porpoise up and down when the worn shocks were overcome by front end lift, it was scary.

[vanzuuk1]

True
Could you get the same info with a wire tie on the front shock shaft? On a smooth road, get the car up to a given speed and measure how much travel you used up, then repeat without the spoiler. It would work on some cars, but I dont think it there would be enough access on an early camaro.

[Damn True]

David How do you decide how much rake? , I was going to shoot for about an inch with a 3/4 full gas tank.

My dodge used to porpoise up and down when the worn shocks were overcome by front end lift, it was scary.

Every source I have read says 1-3 degrees.

[Damn True]

True
Could you get the same info with a wire tie on the front shock shaft? On a smooth road, get the car up to a given speed and measure how much travel you used up, then repeat without the spoiler. It would work on some cars, but I dont think it there would be enough access on an early camaro.

That would only tell you how much the suspension compressed. If it was being extended you wouldn't have an indication by that process.

[vanzuuk1]

If you sealed the grill openings(you cant , this is just hypothetically) and ran a belly pan and had no hood openings, the air that went below the bumper to the underside of the car (a car with 0 rake for the sake of argument) it should cause lift because the air being forced under the car would cause higher pressure. Yes??

If the car had a bulldozer spoiler that forced the air over the car that lift would be eliminated. Assume again that the belly pan from the leading edge of the front spoiler.There are a lot of different areas that come into play , I am trying to isolate this to just the air that does or does not go under the car from under the bumper.

My point is that I think air that is redirected from the bumper to under the car causes lift, all else being equal.


And all you have to do to illustrate trackrats point about underhood pssure is drive a camaro with a glass hood, at high speed you can see the rear corners of the hood strain against the pins.

[vanzuuk1]

I dont think you could ever achieve this with a camaro, but this is a photo of a ferrari f1 car (model) that shows a true ground effect car, upside down wing shape to make down force and skirts that drag to seal the underside of the car to the track. The skirts were banned but later f1 and gtp cars do generate enough downforce to theoretically drive upside down. I tried to find a picture of a lotus 79, considered one of the better ground effect cars, but I had the ferrari model on my desk.

[vanzuuk1]

True I said it backwards, you would measure first without the spoiler and then with the spoiler.

I am starting to post so many times in a row I should move to the cuda at sema thread.

[gonein67bird]

I saw that on the news awhile ago, but I didnt think it would be done for a year or two, Open track day here I come, I'll let you know how the splitter does. God bless Larry Miller! Go Jazz!

[BA.]

fwiw, there was an article some time ago in one of the big magazines that tested a 69 camaro's aerodynamics, and the effectiveness of changes they would make to the spoilers and even adding side skirts by measuring the length of coast-down time. Say, from 80-40mph or 80-20mph.
They found the stock spoiler to work amazingly well, and the side skirts to not be very helpful at all ....for them. (I found that odd considering Indy cars like was mentioned earlier)

I'll try to post it up later.

[Colvindesign]

Hey guys interesting thread you got going here.

The Ferrari's posted employ Venturi Tunnels.

The basic principlie of this is;

the air comin gunder the front of the car is not compressed, it is what would naturally flow under without any air being pushed under (helped with the splitter which splits the airflow in the front). The air is in it's normal density, then it is expanded causing it to actually pull the air from the front, to the back, to equalize the pressure.

Simply putting a full belly pan and a splitter will reduce under car drag, but will not necesarily improve handling. Downforce creates more pressure on the tires, meaning much better grip. Lift...... well it lifts the car up off the tires, and you know the effect of that.

The engine compartment does need airflow and the best race cars have ducts worked into the hoods to both extract heat, and create enormous downforce.

I am working on a design for a Second Gen Nova that will employ
a venturi style underbody,
a front end that will have the entire front end opening ducted through the radiator and up through the hood,
a front splitter
a 1 degree rake

It will ride about 3 inches off the ground and will have 1000hp to try to hit 200 mph. One thing we are going to need to do is make exagerated Venturi tunnels and use a very stiff suspension to prevent bottoming out at speed. If you bottom out, you are recreating the same thing that caused the GT1 class cars to start flipping a few years ago. It also messes up handling severely, etc. BTW, I am designing it, not building it. Someone else is building it.

[Fuelie Fan]

If you sealed the grill openings(you cant , this is just hypothetically) and ran a belly pan and had no hood openings, the air that went below the bumper to the underside of the car (a car with 0 rake for the sake of argument) it should cause lift because the air being forced under the car would cause higher pressure. Yes??

No, or at least not necessarily. the point of running a belly pan and diffuser is to create a "venturi" beneath your vehicle. The area reduction between the front of the car and the bottom creates high speed, low pressure air beneath your car. The pressure differential top to bottom pushes your car downward. The diffuser then re-introduces this low pressure air to atmospheric air as it exits the rear in a controlled manner to reduce drag.

[BA.]

Alright, I promised I'd post this old Car Craft article on aerodynamic tests they did on the 69 Camaro so here it is!
It's a bit of an interesting read. They tried a stock car, a stock spoiler and then made their own front 'air dam' thing and side skirts too.

[gonein67bird]

thats a cool article.The best they tested was with the stock spoiler! I need to do thet test with my splitter off then see how much drag I get with it on.

[Rick Dorion]

I'm having a difficult time printing the whole page. Looks very interesting. Any input on what I'm doing incorrectly? I lose the bottom part and can't resize, etc.

[BonzoHansen]

I'm having a difficult time printing the whole page. Looks very interesting. Any input on what I'm doing incorrectly? I lose the bottom part and can't resize, etc.

Save the images to your computer. Add them to a Word file and print that. (Insert | Pictures | From File...) Make the document borders small first, like 1/2" first and word will auto fit it if it is too big. Then print.

[Rick Dorion]

Hmmm. Tried but it's still too small.