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Old 07-09-2008, 12:49 PM   #11 (permalink)
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Originally Posted by twentysixtwo View Post
Very cool. What you are seeing with the are dams just in front of the tires is what are know in the industry as "Tire Kickers" which push the air down around the tires. The front air dam does a lot of the same so that you don't have air flow over the underbody which has a lot of anti-aero crap (suspension and exhaust bits)

If you have a belly pan, the lower air dam would get a lot smaller.
The main goal for the airdam on this car is for the radiator at speed, and of course like you said keeping air off the chassis.



Here's the underbody shot showing the radator and the air dam. Looking for something to replace the "tire kicker" on the passenger side. I did a good bit of work yesterday fixing all the stuff on that bumper. The two covers next to the radiator opening were hanging down some (jsut missing screws) and the driver's side tirekicker was damaged where it mounts to the bumper, scrap-age lol.. So fixed all that and screwed the panesl back up.



I'll need a heat gun to soften the plastic and shape it flat again..



I'll dig around and see if I can find some lexan to cover the broken fog light lenses.
Aerohead, in one of his installment threads he had said that the rear wing was tested to help smooth the air flow off the back. Was on the 84 T/A if I recall right, and the 84 has the same wing as this Firebird.

But never-the-less, it wasn't so gas hungry yesterday. I'll have to ask my dad what the mileage as yesterday, but drove over to his work and we fixed the a/c (now I can keep the windows up, TX heat is crazy), and it was roughly a 35-40 mile round trip. I was fully expecting to waste over an 1/8th a tank on it. Kept driving habits in check and it managed to only suck a bit over 1/16 of a tank, 10 minutes of stop-n-go traffic included.

Not too bad, typically a 30 mile trip cost me 1/8th a tank

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"All I know about music is that not many people ever really hear it. [...] But the man who creates the music is hearing something else, is dealing with the roar rising from the void and imposing order on it as it hits the air. What is evoked in him, then, is of another order, more terrible because it has no words, and triumphant, too, for the same reason. And his triumph, when he triumphs, is ours." -Sonny's Blues

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Old 07-09-2008, 01:16 PM   #12 (permalink)
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Airdam and tongues

Airdams (and the flexible flaps you see hanging down on some vehicles) do help the radiator but primarily when you are stopped.

The worst case for cooling is typically when you stop at a stoplight or pull into a drive through. The air coming out of the radiator bounces off the engine and ground and gets sucked back into the front of the radiator (recirc / stagnation).

This can have the effect of raising the rad intake air temp by 60 degrees or more!

When you are at speed your radiator almost always sees ambient air temp so even though your engine is pumping out more heat, air dams don't really change the equation.
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Old 07-09-2008, 02:10 PM   #13 (permalink)
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Quote:
Originally Posted by twentysixtwo View Post
Airdams (and the flexible flaps you see hanging down on some vehicles) do help the radiator but primarily when you are stopped.

The worst case for cooling is typically when you stop at a stoplight or pull into a drive through. The air coming out of the radiator bounces off the engine and ground and gets sucked back into the front of the radiator (recirc / stagnation).

This can have the effect of raising the rad intake air temp by 60 degrees or more!

When you are at speed your radiator almost always sees ambient air temp so even though your engine is pumping out more heat, air dams don't really change the equation.
Maybe on a typical car with a typical nose (with a grille there). Ask any F-Body owner that knows well about their car, and ask them to take off the air dam and drive the car around at speed. Most will refuse. Or ask one who has had their's accidently ripped off on a rough road or something.. I can have the folks over at Thirdgen.org back me up on this as well. My air damn is bent back from 18 years, 270,000 miles of driving and drive-ways, but stock they stick straight down to an effect..

I'm not trying to start an argument over the basics of an air dam, but on these cars and in my experience and other F-Body owners I've talked to; they rely on the air dam to push air into the radiator, or they over heat.
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"All I know about music is that not many people ever really hear it. [...] But the man who creates the music is hearing something else, is dealing with the roar rising from the void and imposing order on it as it hits the air. What is evoked in him, then, is of another order, more terrible because it has no words, and triumphant, too, for the same reason. And his triumph, when he triumphs, is ours." -Sonny's Blues
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Old 07-09-2008, 02:28 PM   #14 (permalink)
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You would certainly know more about how this works on an F-Body than I would - I was making more of a general statement based on my professional experience, and for every rule there are always exceptions....I hope my posting didn't appear too dogmatic or declarative (I think I said they do help but primarily when stationary)

I just took a closer look at your pictures - no front end opening makes your vehicle a "bottom breather" so yes, the flap will be helpful at speed, which I believe was exactly your point.
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Old 07-09-2008, 02:57 PM   #15 (permalink)
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Quote:
Originally Posted by twentysixtwo View Post
You would certainly know more about how this works on an F-Body than I would - I was making more of a general statement based on my professional experience, and for every rule there are always exceptions....I hope my posting didn't appear too dogmatic or declarative (I think I said they do help but primarily when stationary)

I just took a closer look at your pictures - no front end opening makes your vehicle a "bottom breather" so yes, the flap will be helpful at speed, which I believe was exactly your point.
It's allright, no harm done. I'll take professional input when ever I can.

I wonder if Z06-style flaps infront of the tires could help divert air over them. I can't remember if they were for down force or to move air around those fat tires..

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"All I know about music is that not many people ever really hear it. [...] But the man who creates the music is hearing something else, is dealing with the roar rising from the void and imposing order on it as it hits the air. What is evoked in him, then, is of another order, more terrible because it has no words, and triumphant, too, for the same reason. And his triumph, when he triumphs, is ours." -Sonny's Blues
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Old 07-09-2008, 03:16 PM   #16 (permalink)
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My guess is they serve the same purposed as the kickers- flow would re-attach after the wheel well. I don't think this would do much for down force although ou never know. If you take it to an extreme (make it 3x bigger and attach to a front end splitter) then it would probably help with front end down force.

My experience is that there is a lot of "art" to aerodynamics - there's a lot you can't tell unless you're in the tunnel.
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Old 07-09-2008, 04:24 PM   #17 (permalink)
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Quote:
Originally Posted by twentysixtwo View Post
My guess is they serve the same purposed as the kickers- flow would re-attach after the wheel well. I don't think this would do much for down force although ou never know. If you take it to an extreme (make it 3x bigger and attach to a front end splitter) then it would probably help with front end down force.

My experience is that there is a lot of "art" to aerodynamics - there's a lot you can't tell unless you're in the tunnel.

One the Z06 it's connected to the front splitter/chin spoiler. If I remember right when Topgear did their review (it's a fun to watch episode too), he mentioned they were to aid in downforce.

But, not the case in my car, but I did give it a shot. The tires stick out a good amount on the car stock. So I did another ghetto'd test. I set the garage fan on the floor, with a mister infront of it to blow over the side of the fender and into the tire (not low enough to blow around the air dam or much of the bumper.. but good enough for what I was looking for). The mister was just to visulize the air movement, and also it had the effect of making the tire wet were it was hitting on the leading edge.

The setup:


1st test, stock:


On the, the dark area is where the water (and thus, air) were mainly hitting. It's a good 1/3~ of the tire. Also when I stuck my hand into the wheel well, you can feel the air being blown up into the front of the wheel well and blowing around inside (turbulance?)

So I used a magazine, and duct taped it to the inside of the wheel well:




So I jacked up the car, and spun the tire around to the other side to keep everything in the same place, and started the 2nd test

2nd test, flare:



Here, you can see with the flare, much, much less of the tire was hit with the water/air. And also when I stuck my hand into the wheel well, there was no air tubulance inside. Came to my surprise, so I took the flare off and stuck my hand in only to feel it windy in there again.



Opinions?

I'm looking at subtle mods to the car to make it better. I wonder how much of a difference it would make on all 4 corners, on top of having the moon-dish wheel covers (which I do think look cool).
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"All I know about music is that not many people ever really hear it. [...] But the man who creates the music is hearing something else, is dealing with the roar rising from the void and imposing order on it as it hits the air. What is evoked in him, then, is of another order, more terrible because it has no words, and triumphant, too, for the same reason. And his triumph, when he triumphs, is ours." -Sonny's Blues
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Old 07-09-2008, 05:52 PM   #18 (permalink)
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Lovin' the ghetto aero tests

It is subtle, but it does seem to help and at highway speeds it should block more of the tire. Some chopped up cheap mudflap and you're good to go!
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Old 07-09-2008, 06:27 PM   #19 (permalink)
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Awesome on-the-fly tests! Cheap and effective for quick spotting and analysis.

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