The Single BEST photo of your Festy

[DriverOne]

Re: The Single BEST photo of your Festy

Hey, nice Aspire! That's looking real sporty, and I love those shark fins!

[Festevil3]

What are those "shark fins"?

[rmoltis]

They're called vortex generators. They help reduce low pressure seperation of airflow at the rear end. Which in turn creates more downforce and helps with accelleration slightly. Airplanes started using them to help keep the wind flow attached to the surface of the wings which in turn let's them take off at lower speeds and increases their stall angle. Vortex generators are made in different shapes and sizes. Here's a couple of research articles to give a read to. The first article give a detailed description of vortex generators used on the roof of a car. They test it in a wind tunnel and give/explain the result quite detailed. And the second link gives some good pictures of the fluid dynamics involved.

http://www.google.com/url?sa=t&source=web&cd=13&ved=0CG4QFjAM&url=http%3A%2F%2Fwww.mitsubishi-motors.com%2Fcorporate%2Fabout_us%2Ftechnology%2Freview%2Fe%2Fpdf%2F2004%2F16E_03.pdf&ei=kBn4UMz2LLGu0AHOsYBo&usg=AFQjCNHArFCd4qeAHReUfG5fPxrlj7fL8w

http://arc.uta.edu/research/vortex.htm

[TheresGabe]

Wait a second.. I've always heard they are pointless on FWD cars. They are pretty much used for cars like EVO's that are either RWD or AWD... How would pushing the back end down on a FWD car help with traction? Or am I way off?

[rmoltis]

downforce is used to increase traction. so ideally you would want to apply it wherever neccessary to balance the whole car out. the aerodynamics really come in to play once you start moving faster. for fwd cars the front of the car has the weight of the engine directly over the wheels giving it some good downforce, but stays light in the rear. so adding some rear downforce helps out a bit. a windsplitter up front would split the incoming air and cause more to rush over the front of the car causing more downforce on the front.

where as in a rwd car the engine is up front giving the extra weight to the non powered wheels and the rear end stays light which could also use some rear downforce.

say you take a left hand turn and most of your weight shifts to the right two wheels now the inside (left set of wheels) has less traction. the downforce would give those inside wheels more grip\traction, and it would help keep the rear end or front end level depending on what needs improvement. it helps out to prevent more bodyroll which can help put more power to the wheels and keep the wheels on the ground. in turn it would make your suspension feel more predictable. which helps you go faster without reaching your limits.

now on the other hand if you have a 150+mph sports car that goes so fast it wants to lift off of the ground while going down a straight road. you may need the downforce to just to keep it grounded which would also help increase top speed potentially.

[TheresGabe]

I'll bet the subs in your picture hold the rear end down more than your fins though... Good looking Aspire. Best one I've seen in awhile. Makes me miss mine!

[rmoltis]

Thx. And yes the weight back there makes my car sit level front +rear. Also the 44lbs of dynamat.

These cars are so efficient and reliable. I can't believe more people don't drive them. Festiva or aspire, I'm hooked.

Here's my last aspire. And the build thread below it.

http://aspire.b1.jcink.com/index.php?showtopic=594

[Darlo]

I would like to chip in by saying that YES the vortex generators have a purpose, however on your aspire you will mainly see a decrease in your Cd (aka drag coefficient) therefore saving you gas. The other implied benefits will be less than significant IMO, and even the MPG savings will be small. This is mainly because of the speed that you will be travelling (much slower than a jet or lambo, lol). If anyone recalls my Kamm-back experiment, this somewhat shows how little effect even taking it to the "extreme" that I did. I only saw about a 3% increase in MPG (which is significant when you are already getting 50mpg). I would have loved to have tried these vortex generators in conjunction with the Kamm, just to see if there was a large effect. Take a look at the Kamm-backhttp://www.fordfestiva.com/forums/sh...highlight=kammAugust 14 (Festiva Kamm) 024.jpgAugust 14 (Festiva Kamm) 025.jpg

BUST OUT THE SCIENCE! lol

Ps. Hey rmoltis, where are you located? What makes you so interested in the science aspect of all this? I love stats, math, and anything MPG related, so I am always interested when someone else "speaks my language", lol.

[rmoltis]

i live in the pittsburgh area, anyone else in pa?

i love the science, and i must say i wont do something if i dont think it makes sense. best of all when people ask you why you did something science can always provide a logical answer instead of... "i dunno someone told me to do it."

i was originally looking for an upper spoiler because they basically serve a similar purpose. but seeing as they are obsolete\hard to find that wasnt an option. i could have gotten the lower spoiler but people already have those and theyre not very unique. so the last step was i always liked the vortex generator kits that were sold for the sti and evo. and it got me wondering if i could apply those to my car. then after a few articles of research later i determined that the vg's would make the least impact on weight, frontal surface area to wind, cost, and would add to downforce.
the biggest factor was that it would be a unique addition that was also functional.

i like all the aero mods youve done theyre awesome. better yet they serve a purpose. i bet your accelleration improved with those aero mods enough to feel your engine not pushing as hard.

i guess when you do your research in advance and then plan something out. it tends to work out either exactly as planned or better. but going in blindly sometimes leads to many extra steps to rectify problems or unforseen variables. or maybe you just dont like the specific function something adds. the science usually spots the problems before the project even starts. and designing your own ride unique to your specific personality is like art. you dont wanna follow exactly in someone elses footsteps you want to blaze your own path, and be remembered for your unique traits. not be an example of what everyone else does. It's all just fun.

[Darlo]

No matter what, if you lower your Cd (drag coefficient) you will see better acceleration. This is mainly due to the fact that, at speed, over 40%-60% of your engines power is going towards overcoming air resistance! If you reduce the air resistance, you will have more % of power to put towards other things, such as acceleration. This of course can be negated by a couple of things, such as traction etc, but in my Festiva.........never had to worry about that, lol..........I did get 500+miles to the 10 gallon tank......

[bondo]

nvm

[neanderpaul]

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[ernst]

My beloved pride...

[Festevil3]

REALLY NICE

[TheresGabe]

Saturday night... I was invited to a NeoGeo party in Ogden UT. It was snowing pretty bad, and it's 50 miles one way, but I decided I'd go anyway. My friend while driving in front of me in his 1996 AWD Subaru spun and hit a guardrail (He is fine just dented a fender). The Festiva made it there and back, passing 20+ cars spun out... I love my car.