aero stuff

[gonein67bird]

just wanted to show off my splitter and air diffuser.

[Damn True]

Very cool!

Let's have some pics of the whole thing. I have been rolling a bunch of aero related ideas around in my head. I'd like to see more of your setup.

[TitoJones]

That freaking rocks balls. I really like it, especially because it looks like a 'bird.

Tyler

[vanzuuk1]

Photos of the whole car please, I really like it.

[gonein67bird]

I will post some pics of the car when I get home from work,maybe I'll even clean it a little those pics are all dirty

[USAZR1]

Please include a rear shot of your diffuser.

[gonein67bird]

well here it is a 1967 pontiac firebird 326 ci th350 trans. always wanted to do something with the front but i'm no master fabricator so I decided to do a splitter I just used a sheet of alum. I attached to the 3 mounting holes for the spoiler brace, then ran it back to the cross member and screwed it in to that.I added the carbon fiber supports into the to holes for the front plate.You can bounce the car with your foot on it,just like vanzuuki1 once said about his.the rear was a little harder I had to bend the alum.to fit around the gas tank hooked it to the gas tank strap bolts in the back and to the rear lip of the car on the other end.Then I cut out some carbon fiber and riveted it to some alum. angle. I want to finish it by welding some more alum. to the sides to totally enclose the the gas tank. The spoiler is a 69 Trans Am style built for the 67 body. The int. also has carbon around the radio and gauge pod. I dig carbon if you cant tell.I think I'll name her Carbon Fire! Yo Tito glad to see someone of your how do I say, Big timeness likes what I did. I want some of your rockers to finish it off!!! by the way dont mind the wheels I am currently triing to find some affordable bbs style wheel with correct bs, like the ones steve68ls2 has.

[trackrat79]

I am interested in its actual mechanical efectiveness. Have you noticed any difference since adding the pieces. I am trying to build a euro styled nastruck but want body mods to have function over style.

[gonein67bird]

I just did it this fall, have not had it up over 70 yet, the splitter by it's nature can't help but improve down force on the front spoiler,and as they said in the 05 sept. HotRod aero tricks you can use. a splitter adds downforce without adding drag and if extended around the sides it helps keep air out of the wheelwells. the diff. helps staighten out and eccellerate the air coming from under the car. But I dont know if it will do much, it just looks bitchen!

[Rick Dorion]

What gauge aluminum? Great job!

[speedster]

Car looks very cool. I like the work you did on that front (and the rear), and one of the things I like best is that YOU DRIVE IT !!
Heck, you even have snow in the background.
From another Birdbrain...

[trackrat79]

Aero dynamics can start to take effect at as little as 40mph. At 70 you should be able to sence a differance but it mite be so small that if your not realy concentrating on it you mite not notice. Also the hot rod areo tricks is wrong. It is nearly imposible to add downforce without drag and to do it you're getting in to complex airfoil shapes. Even you're rear diffuse will add downforce and possibly drag. You're splitter is forcing air that would normaly go under the car and exit straight out the back with little disturbance up into the engine compartment were it gets trapt and causes drag. The hope is that it's benifits outway its negatives.

[vanzuuk1]

Thar car looks good now, when you get some new rims it will look awesome. Nice to see a step to the side, stylewise.

[gonein67bird]

Air that goes under the car is bad I thought, hence race cars having a flat and smooth pan.The splitter is flat and extends back to the front of the engine. Any air kept from going under the car improves aerodynamics .The diffuse only changes direction and speed of the air coming from under the car, how does that cause drag?

[gonein67bird]

Thanks vanzuuki, I think Damn true's post awhile ago "wierd aero stuff" that had your car in it(way cool car) got me started on this stuff.I hadnt seen anthing like that till I read that post and saw your car!

[vanzuuk1]

My impression is that the air that normally goes under the car caused lift, when I put my spoiler on you could notice a little more drag when you let of the gas. The car feels more stable and does not wander around as mich so its a tradeoff.

Your splitter might stop some of the air on its way under the car and change its direction, you get less lift but a little drag.

I dont think the diffuser causes any drag.

Obviously I dont have a wind tunnel so this is just opinion.

[trackrat79]

First no the air that would normaly go straight thru under the car does not cause lift. What causes lift is the air that is forced under the car by the shape of the body and the openings in the grill. Were does the air go after it passes thrue the rad? Well enless you run a cowl hood un sealed or some type of gills in the fenders all the air is force to press against the firewall and down under the car to exit out the back. That is where your front end lift comes from. The only real way to get rid of this problem is to shrowed the exiting air from the rad and direct it out the hood, the bonus is that if done right you won't beleave the down force this creates. Back to the air under the car. The air that goes under the car causes drag not so much lift. But the more you do to smooth out the underside or your vehicle the better. Yes the diffuser alone may not give a noticeable amount of downforce but with a few extra pieces you will be amazed at the differance. Fast smooth free flowing air over a given surface generates pull. The smoother and faster you can get the air to exit from under the car the more pull will be aplied to the underside of the body. Then the shape of the diffuser creates even more pull buy acting like the under side of a wing. As the air exits the back of the car it try's to follow the curve of the diffeuser and generates more pull. The best examples are the ferarri streat cars like the Enzo and the f-5O.

https://www.pro-touring.com/forum/attachment.php?attachmentid=8023&stc=1
This (http://this/) is the best shot I could find. This car has no big wing on top to generate down force it is all done by the shape of the top of the body and the shape of the belly pan. It all woks together as a system. You could almost drive this car upside down it generates so much downforce.

All this is my own understanding of how things work from personal knowledge and expieriance. I have no formal education in aerodynamics. The majoraty of my enderstanding comes from my father who works in the military jetfighter industry.

[gonein67bird]

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:

[trackrat79]

I think esteticly you did great. It adds a bit of racecar flare without being to obnocious. The two things I think I would change is make the chin spoiler in the front longer and extend the fins on the difuser down a few more inches and all the way to the front of the tank. Did you make the carbon panels or use pre fab ones.

[gonein67bird]

What do you mean by longer? the carbon was a sheet of I think 1/8th inch I got off ebay and then cut to fit.They are 4" long on the long side wich puts them 9" from the ground.The front splitter is 6" from the ground.

[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/restoarchives/winter99/18-21camaro.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.