Does anyone have any ideas of how to improve aerodynamics. I have an extractor scoop that helped more than anything else could have. Lowering the car helps. My question has anybody came up with an idea of how to reduce the low pressure area behind the back window? Would more rake and a roof mounted lip spoiler help?

do you want downforce? or a lack of drag? or a balance of both...

a chin spoiler combined with an efficient hood vent and a rear spoiler will make the fiero extremely stable - firmly planting the tires - however the chin spoiler does reduce the top speed due to drag (I know i've done it)

put a panel that goes from the rear of the roof to the rear of the rear deck - basicly close in the rear area - like a hatchback

quote Originally posted by Pyrthian: put a panel that goes from the rear of the roof to the rear of the rear deck - basicly close in the rear area - like a hatchback

That may do more harm than good. That low pressure area behind the rear window serves 2 functions.
1. It draws out hot air from the engine compartment.
2. It reduces rear lift by venting air from under the car up through the engine compartment.

You might want to smooth the airflow and possibly add a larger rear wing for more downforce, but you need some of that negative pressure to keep the airflow under the car and through the engine compartment.

Belly pan! The airflow under the Fiero is a MESS. If you route your radiator airflow out through the top of the hood (you said you built an extractor scoop?), and divert any remaining airflow from the radiator or air dam area under the car into the right places in the engine compartment for cooling, you will greatly improve high speed stability. Just don't forget that the radiator airflow was originally designed to go under the car so it gets to the engine compartment to keep air circulating there. You may want to duct a vent into the engine bay from the right side quarter panel since you're still not going to get as much airflow with some of the radiator air going out the front hood.

I want both downforce and less drag. I don't want a chin spoiler because I plan on a 2" drop and I have heard that the chin spoiler hangs too low. I have been looking into a lip spoiler on the roof something very subtle. I figure that will add some downforce and really won't increase drag. The stock wing needs more attack and height, but the wing stand extension cost more than I will ever pay. i was thinking of an aluminum spoiler that doesn't look too ricey or out of place.

I started this thread for help and for anybody's ideas for what they might think could help any fiero.

[This message has been edited by goatnipples2002 (edited 11-17-2005).]

quote Originally posted by goatnipples2002: I want both downforce and less drag. I don't want a chin spoiler because I plan on a 2" drop and I have heard that the chin spoiler hangs too low. I have been looking into a lip spoiler on the roof something very subtle. I figure that will add some downforce and really won't increase drag. The stock wing needs more attack and height, but the wing stand extension cost more than I will ever pay. i was thinking of an aluminum spoiler that doesn't look too ricey or out of place. I started this thread for help and for anybody's ideas for what they might think could help any fiero.

the stock "wing" isn't a wing - its a spoiler.. the most effective spoiler on the fiero is the IMSA wrap around for the notchy and the whaletail for the fastback..

there are other chin spoiler options that aren't as big - or you can make a custom version

having a slight rake to the cars stance will also help

but the next most important part of stability at speed is tires and suspension..

quote Originally posted by goatnipples2002: Does anyone have any ideas of how to improve aerodynamics. I have an extractor scoop that helped more than anything else could have. Lowering the car helps. My question has anybody came up with an idea of how to reduce the low pressure area behind the back window? Would more rake and a roof mounted lip spoiler help?

Don't worry about the back window, and the Fiero wing is the right size. You just need to be able to adjust the angle. From what you have done I would put on a chin spoiler, NOT A AIR DAM. You can pick up a chin spoiler that will bolt on that just needs some trimming on the ends from a Ford Taurus. I got mine off a 92 I believe. Don't laugh, look and measure. And they are easy to find .

[This message has been edited by gunnie (edited 11-17-2005).]

Hey gunnie, do you have pics of that chin spoiler installed?

Kohburn,

The fiero wing is a wing. A spoiler is a body extention where air cannot pass under, a wing is a seperate aerodynamic device which stands off the body, such that air can pass under and over it.

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Thanks Aus!
More info at: https://www.fiero.nl/forum/Forum1/HTML/043357.html

quote Originally posted by Bigfieroman: Kohburn, The fiero wing is a wing. A spoiler is a body extention where air cannot pass under, a wing is a seperate aerodynamic device which stands off the body, such that air can pass under and over it.

it may look like a wing but functionally it is a spoiler - a spoiler does not have to be sealed against the body work to be such

air does not flow under the fiero wing in any measurable extent except sometimes backwards from the bumper up the taillights and under the wing.. however the airflow at the top of the wing is that of a sealed spoiler, it does not have the aerodynamic properties of a wing - it was designed as a spoiler and works as one (unless it is raised up higher, in wich case people should smooth the bottom ridges off of it for better airflow)

I've been correcting misconceptions about this for years, and probably will continue to do so

its be proven with string tests that it functions as a spoiler.. though the IMSA style is far more efficient at it - creating essentially a bubble behind the back window that improves downforce and smooths out airflow thus reducing drag (as proven by the published drag coefficients for winged and wingles fieros) - a wing does not reduce drag - a spoiler often will

it would have to be jacked up like so to change the airflow characteristics

but this has proven the most effective method

[This message has been edited by Kohburn (edited 11-17-2005).]

quote Originally posted by Blacktree: Hey gunnie, do you have pics of that chin spoiler installed?

I'll try and get a picture of it tonight and post it if I can figure out how to do it. The car is on the rack in the garage with my 05 Mustang parked under it. We have snow, ice and cold here in Iowa so I don't want to do much moving around.

quote Originally posted by gunnie: You know- I read that science and engineering have proven that a bumble-bee can't fly. The wings are too small for the weight of the body. And now, in thinking about it, I don'y think they really have wings. They are shaped wrong..

all they proved was how little they truly understand about fluid dynamics

just want to verify, cuz i forget. downforce i know basically holds down the back end and drag reduces top speed correct? anyway if you reduce drag wouldnt that reduce the amount of air pulled through the engine bay?

edit: i posted this and then realized this was the perfect thread to ask an aerodinamic (probably spelled wrong) question i've been trying to figure out.

i have an 88 gt that i am in the process of building i have the quarter window scoops, not sure how much they really do if anything but they will be going on the car and i will be adding a hood scoop to the deck lid. i am trying to figure out the ideal spoiler, or wing that will work with this setup. everybody who puts the scoop on the decklid is useing ti to suck additional air out of the engine bay correct? is it possible to use it for the engine to suck air in (i know a roof scoop would work allot better but i already have a sccop that i would really like to make work and it has to face to the rear) i saw a duck tail style wing(?) on somebody car here which had a few hole underneath it. i was thinking that might work for me i want to get down force but i want air to be able to be pulled into the scoop if possible. performance is obviously important or i wouldnt even be asking this i would just put something on but if it doesnt work i dont want it so i want to figure out what would work best but of corse it still needs to look good also.

thanks, dont mean to steal your thread

[This message has been edited by crash1369 (edited 11-17-2005).]

yes if you get a wale tale spoiler like cali kid has on his GT - and put a rearfacing scoop thats sealed to the engine intake you will get good airflow to the engine -- atleast one of the imsa racecars used this high pressure zone by the waletale to help feed the engine fresh air..

just one example.. the aiopening there sealed to the bottom of the decklid just infront of the spoiler

[This message has been edited by Kohburn (edited 11-18-2005).]

Let's be realistic for one minute here. Where do you plan to drive your car that will require these modifications? Most of these will have no effect on daily street driving. The also will not work to any usable effect till you are probably doing twice the speed limit. The only place I can see this happening is at a racing track. If you plan on taking your car there, then spend the time to research which modifications will work best with your car. If you plan to drive your car on the street, then you are only doing these for looks. Let's be realistic about this.

quote Originally posted by Kohburn: yes if you get a wale tale spoiler like cali kid has on his GT - and put a rearfacing scoop thats sealed to the engine intake you will get good airflow to the engine -- atleast one of the imsa racecars used this high pressure zone by the waletale to help feed the engine fresh air.. just one example.. the aiopening there sealed to the bottom of the decklid just infront of the spoiler

Doesn't this effect the down-force? Or is the spoiler oversized to compensate? I wonder what speed he has to go to achieve the high pressure zone.
Is that his swaybar going under the intake? Looks small.

Aerodynamic devices can be utilized at any speed, but start to become more noticable at highway speeds. The faster you go the stronger the effects of these devices. Why is it that people think you must be going 120+ mph for aerodynamics to matter? Just so you know the use of wings, spoilers, splitters, canards, air dams and any other aerodynamics devices can help you save gas, achieve a higher top speed with out engine mods, help you stick to the road at speed and they can help when cornering/autoX. Now where you choose to do these things is another story. I do agree that alot of people don't do enough research and just do things for the looks.

quote Originally posted by gunnie: Doesn't this effect the down-force? Or is the spoiler oversized to compensate? I wonder what speed he has to go to achieve the high pressure zone. Is that his swaybar going under the intake? Looks small.

the CFM used by the engine does not compare to the airflow in the area..

don't need as big a sway bar when you run stiffer springs

Aerodynamics is important for daily drivers, too. Any modification that reduces aero drag will also improve fuel economy.

As Kohburn explained, a correctly sized spoiler will create an air bubble behind the rear window, a "virtual hatchback" if you will, that will help keep the roof airstream flowing toward the back with minimal fuss. And minimal fuss = minimal drag.

This is very similar to a tactic that is used on convertibles to calm down the airflow in the cabin when the top is down. They place a bulkhead of some sort (usually plexiglas) behind the seats. It causes the airstream to go over the windshield, across the top of the cabin, and back down behind the bulkhead, instead of just dropping into the cabin and creating a turbulent mess. The end result is less aero drag, and less time spent fixing your hair.

A couple things to remember:
1) Turbulent air resists motion... just like a gyro. So turbulence creates drag.
2) For every action, there is an equal and opposite reaction. If your car is pulling air along with it, that air is pulling backward on your car (i.e. drag).

Unfortunately, the Fiero has both of those things going on right behind the rear window, which is why I suggest the spoiler + deck vent strategy. It combats both of those things, by keeping the roof airstream nice and smooth, and shoving air off the back of the decklid. And if done right, it should make some extra downforce in the process.

[This message has been edited by Blacktree (edited 11-18-2005).]

OK- I really do agree almost 99% with both of you.
Here is a test- wash you car and then take it for a drive down a gravel/dirt road. You will be able to see the low pressure areas, they will be the ones with the dust sitting on them (behind rear window/back bumper). If you put a spoiler on the low area will increase, but so will you down-force for handling. The trick is getting the amount of down-force for control and having the HP to pull the low pressure area (drag). That's why if you are racing the guy behind you wants to get on your rear bumper, to get into the low pressure area and have you pull him. Also why they say some cars handle better in clean air. A wing is suppose to help break up the air flow over the rear and "help" reduce the low pressure area. Otherwise its only use would be to lift the rear since the spoiler applies down force.
Again, I agree with your thoughts and just want to remind everyone that all of this has a specific function, and one effects the other. There is a lot of difference in installing stuff for looks or trying to correct a problem. Most go for looks and create a problem!

[This message has been edited by gunnie (edited 11-18-2005).]

quote Originally posted by Kohburn: it may look like a wing but functionally it is a spoiler - a spoiler does not have to be sealed against the body work to be such - a wing does not reduce drag - a spoiler often will but this has proven the most effective method

Here we go again. If you know anything at all about aerodynamics you know that the Fiero wing is in fact a wing, that is mounted upside down. It is positioned, however, not to function as a wing, but to interrupt the air flow that comes up the back of the bumper and forward over the deck lid.

When it is raised, it does not at all stop or mitigate the air moving up the back of the car and forward across the decklid. When angled down 5* it will provide downward force when you get to sufficient speed. (not highway legal btw)

This was my setup last year.

I learned the hard way, after installing fans in the scoop, that the air naturally flowed IN the scoop, and not OUT.

This was the car at speed.

This is the actual air flow, based on my observations and experiments

It is absolutely true that the wing does not function as a wing in the stock location. It is also absolutely true that the IMSA spoiler or the whaletail is infinitely better.

If I had an 86GT, I'd be really tempted to put in the Ferrari style of louvers off the back window to channel air over the deck but allow air coming up from the engine to be sucked out. I haven't spoken to the Ferrari engineers, but I don't think the louvers are simply style.

BTW I like these discussions but I'm not adventurous enough to put on a really big spoiler like the race car above.

Arn

Ah, just wash & wax it. You'll be amazed when you gain two mpg on the highway. Seriously.

May not mean much fer racin' though. I guess every little but helps.

I was looking at this spoiler and thought it would look nice and add some downforce and decrease drag at the same time.

Then I found this diagram and it made me wonder about if the drag spoiler would catch clean air or not.

Then I found this diagram and it pretty much explain what a nascar style spoiler does and it sounds similiar to our stock spoilers.

The truck might be hard to see but spoiler on the back is basically a bent pice of aluminum. When I saw that is figured I could place a small fersion of this on the roof for spoiler and a slightly taller version on the decklid.

My reasoning for a roof mounted lip spoiler and a taller lip spoiler on the decklid was this diagram...does this diagram pertain to our cars?

This is an old thread from another fiero forum...I almost sound like I know something...but I really don't.
http://www.automotiveforums.com/vbulletin/showthread.php?t=428631&page=1& pp=15&highlight=aerodynamics

[This message has been edited by goatnipples2002 (edited 11-19-2005).]

quote Originally posted by Formula88: That may do more harm than good. That low pressure area behind the rear window serves 2 functions. 1. It draws out hot air from the engine compartment. 2. It reduces rear lift by venting air from under the car up through the engine compartment. You might want to smooth the airflow and possibly add a larger rear wing for more downforce, but you need some of that negative pressure to keep the airflow under the car and through the engine compartment.

Actually, I've read some streamer tests online where individuals said they didn't really vent out at speed, just hot air rising out of the engine compartment when stopped.

BTW, IMHO best rear aerodynamics without sealing in the rear would be Kameo kid's rear fastback louvers, plus maybe some quarter window scoops for a little more relief if necessary

[This message has been edited by FieroGT42 (edited 11-19-2005).]

im not into the big scoops and monstrocities hanging from my deck ever try adding electric fans to the underside of the existing deck vents? would that not eliminate the "vacuum" behind the back window without obstructing viewor even worse, looking like RICE!!!!!? wouldnt a rear defuser do the same for the rear of the car? just my thoughts...you are way over thinking this...look up GM's windtunnel data, while in motion the deck vents supply air to the deck lid to relieve some of the drag. it was built as an economy car, so im pretty sure GM did somthing for areodynamics to boost MPG #'s. just a thought.

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quote Originally posted by FieroGT42: BTW, IMHO best rear aerodynamics without sealing in the rear would be Kameo kid's rear fastback louvers, plus maybe some quarter window scoops for a little more relief if necessary

I agree with you, althou I've not had the change to yarn it up and see how the wind bfows over, under, and around this set up. Along with the louvers I had some custom wing stands made that put the wing about 3" back farther than the stock location and maintain 5" height which should ad in the flow of air smoothly off the rear slope of the GT.

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still plays with cars..

Front engine cars tend to have most of their weight on the front wheels... That's where the engine sits... They put spoilers on the rear to add downforce to the rear wheels. The idea is to even out the effect of the extra weight on the front wheels.

The Fiero may be a mid engine car, but the engine is behind the driver. There is LESS weight on the front wheels than there is on the rear wheels.. So if the Fiero has more weight in the rear, what is the advantage to adding even more weight ? Is the ideal situation to have 10% of wieght on the front wheels and 90% on the back ?? Would this provide the ultimate 'stability' ?

Rather than just adding some sort of spoiler to "improve aerodynamics" you need to define EXACTLY what you wish to achieve. That's how race car teams approach the problem.

Well I believe there are ways to help the airflow at the rear and the front. You would have to use carnards or slitters on the front end to produce downforce at speed, along with the mid-engine advantage you could use these other things disscussed. I could just hear the rice haters if you used canards on the front of a Fiero.

Just get a roll of 100mph tape and tape up all the seams around headlights, hood and door seams etc.. Works at Bonneville

Then spray Pam all over the car to make it super slippery.... that'll keep people from sitting or leaning on your car also as well as making the air just slide past :-)

Ok, probably not what your looking for...

quote Originally posted by Scott-Wa: Then spray Pam all over the car to make it super slippery

LOL....that's a good one !

Ya know guys, if you're really concerned about improving the Aerodynamics, you'd better have one hell of a lot of work into the rest of that 20 year old Fiero, before testing those changes out. We don't need anymore pictures of wrecked Fiero's here on the Forum.

the shape and angle of the added front vent can give alot of downforce
look at a old FordGT racer front vent
or an M8 can-am car

the ideal is a buried wing inside the car
so the airflow not only vents out but pushs down while flowing out
to do that you need a big vent with a curved wing like shape

to do it right you will need lose the top part of the wall by the spare tyre
to get down near the bottom of the rad not a little slit up top

after the opening for the rad on the bottom a rubber strip added
to limit air flow under the car would help force more air out and up the vent too

in the back the air flow is very complex and turbulent
perhaps a rased wing with an added whale tail would help
what most racers do is open the rear to allow flow directly
into the low pressure area behind the car from the engine
kinda hard with our trunk in the way

[This message has been edited by ray b (edited 11-20-2005).]

Kameo Kid, I like the look you've achieved. I'd also like to see some 6" pieces of yarn taped to your edges @ 60 mph.

I'd be willing to bet any money that there is still air flowing forward across your deck, but I also suspect the vacuum created by the louvers is pulling air out.

Any chance you are willing to do some air stream tests and post your pics?

Arn

BTW, mine were 6" and 12" ribbons and they were too long and too few. Here's what it looked like

When I started this thread it was meant to be about any improvements that pertain to the aerodynamics of our cars. Anybody that has a fiero is probably aware that parts need to be updated/upgraded. I do understand that there is a balance that needs to be attained when working with aerodynamics. Now that's out of the way.

The rubber strip that is under the car in the front that directs air through the radiator acts somewhat like a chin spoiler/air dam IF you have an extracor scoop to vent the air out. This has been proven so that is one way of adding downforce to the front end.

You could get a chin spoiler but i won't because they hang too low when the car is dropped. The only other options are splitters, canards and lowering the vehicle to provide some rake. Lowering is a must...how much is up to the driver. Splitters and canards can look ricey if not done right. I personally think that they will help dramtically.

[This message has been edited by goatnipples2002 (edited 11-21-2005).]

quote Originally posted by Arns85GT: Kameo Kid, I like the look you've achieved. I'd also like to see some 6" pieces of yarn taped to your edges @ 60 mph. I'd be willing to bet any money that there is still air flowing forward across your deck, but I also suspect the vacuum created by the louvers is pulling air out. Any chance you are willing to do some air stream tests and post your pics? Arn

I'm glad you like the look, it still has a way to go. I too would like to see the air flow over the rear with the new stands but I'm guessing that the louvers will smooth the air flow and cause it all to go off the rear of the GT and I also believe they helps pull air out of the engine compartment. Only time will tell and so will I once the tests are complete. The GT is down till at the earliest spring so it will have to wait.

quote Originally posted by Arns85GT: Here we go again. If you know anything at all about aerodynamics you know that the Fiero wing is in fact a wing, that is mounted upside down. It is positioned, however, not to function as a wing, but to interrupt the air flow that comes up the back of the bumper and forward over the deck lid.

so its shaped to look like a wing but is functionally a spoiler - so you agree with me

quote When it is raised, it does not at all stop or mitigate the air moving up the back of the car and forward across the decklid. When angled down 5* it will provide downward force when you get to sufficient speed. (not highway legal btw) This was my setup last year. I learned the hard way, after installing fans in the scoop, that the air naturally flowed IN the scoop, and not OUT.

yes - due to the air flow curling back towards the window like a wave.. having the spoiler control this airflow helps to smooth out the overall flow and reduce drag

quote is absolutely true that the wing does not function as a wing in the stock location. It is also absolutely true that the IMSA spoiler or the whaletail is infinitely better. Arn

[This message has been edited by Kohburn (edited 11-21-2005).]

Goatnipples2002, I agree that splitters and canards can look good if installed properly. More important is there effect.

There is a GT in my area that I've seen at car meets with front splitters and they looked great.

You mentioned that you are lowering the front of your car and don't have clearance for a chin spoiler. I'm heading down the same road, probably a 1.5" drop in the front.

I was wondering if anyone has tested what the increased "wedge factor" will do to the air flow/turbulence behind the back window.

Keep the research and suggestions coming!