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Speculation on EVO VIII Pricing.

This article was taken from a NASCAR Newsgroup. The article addresses a question regarding a 1/4 inch change in the size of the spoiler. Granted the higher the speed the greater the effect this will have.

This thread was started to add some balance to the "What do you think looks good?" threads. Let's talk function for a change! The next time you board a plane I dare you to look to the person sitting next to you and say, "I don't think those wings look so good. They would be much more attractive if they were smaller". :wink:

From: SonofAnath ([email protected])
Subject: Re: Rear Spoiler/Oooppps.....can't call myself a lurker anymore.
View: Complete Thread (5 articles)
Original Format
Newsgroups: rec.autos.sport.nascar
Date: 1997/10/03

In article <[email protected]>, -- <[email protected]> writes:

>Does this spoiler change for Chevy's affect speed, handling, drafting,
>or does it affect something else? I'm very ignorant on these matters,
>but I was wondering what difference a quarter of an inch makes.
>Thanks,

A couple of things need to be addressed in this question. Your talking
about something that just doesn't affect the one car, that the spoiler
changes are made to. But every car that runs in its air flow.

A quarter of inch can make a difference, the question is a difference in
what. And so like anything there are all kinds of advantages and
disadvantages. I'll start with yours: speed, handling, drafting, then
expand it to angle of attack,downforce,and "sweet spots" and finally my
opinion. Also, i'll try not to get to long winded. Or chase any bunny
trails......ya right.

The thing with any rule change is that, changing something as minor as(or
so it seems) a 1/4" of spoiler, doesn't just effect one part of the car.
This may get a little wordy, so if you are already up to speed on these
things, please endure for those who are not. Or just don't read it.

Lets start with some laymen definitions, of certain terms used.

Downforce: Okay, anytime a object is exposed in the airstream (i'll limit
this concept only to rear spoilers). It produces two things, drag and
downforce.That little rear spoiler produces X amount of pounds per square
inch of downforce, at a certain speed, on the rearend of the car. I can't
tell you how much because it will vary with angle of attack, total area of
spoiler in square inches, speed of the car, and how much of the rear
spoiler is actually in the airflow.(which can sometimes be *adjusted* with
shocks, but thats a totally different subject)

Angle of Attack: (once again i'll limit this to rear spoilers) Thats the
angle that the spoiler is positioned at. But there is two factors to
this...one NASCAR regulates the minimum and maximum angle of the rear
spoiler. But number two is you have to understand how angle of attack
works or else it's useless. Example: next time your driving, stick your
arm on the window sill of the car. Then put our hand palm up and flat,
with your fingers pointed to the REAR of the car. Then slowly start raising
your hand at the wrist. What you will feel is downforce, but at a certain
point it will start to feel like your hand is being pushed backward instead
of down. This is the same thing that happens on race cars. At a certain
point the amount of downforce stops and it strickly becomes drag.

Lift: Oh this is going to be tough........lets see where do i start,
without getting into low and high pressures. For example purposes lets
imagine we are looking at a car from the side, strickly 2 dimensional. As
air approaches the front of the car it's got two choices go over or go
under (Please remember this is 2 dimensional). The air traveling under the
car, has a straight shot right out the back, (we won't count for tires or
undercarriage getting in the way of the airflow) but while traveling under
the car the air is exerting force on the road(which is solid) and the
bottom side of the car (the car is not solid, it's able to be moved). The
air going over the car, is forced to travel a greater distance, since it
must follow the contures of the body. And in that process it reduces the
pressure of the air on the top side of the car, causing a lifting motion
from the bottom side. Perfect example is a airplane wing. Same principles
apply.

Drag: The resistance or displacement of a fluid created by the "shape" of
a body in motion going through that fluid.....(and thats simple terms).
Example: Next time your in the tub turn your hand(vertical with the water)
to make it as slender as possible. Then run it through the water,note the
amount of resistance. Rotate your hand (keeping it vertical) 90 degrees,
and repeat the process. You can definatly tell the difference...when your
hand displaces more water you have to push harder. It's the same with a
race car. Its the body of a car being pushed through a body of fluid, air
being that fluid. The idea is that a car with a given drag coefficient,
with a 550ft/lbs of torque(sorry guys or girls, i don't believe in
horsepower.) motor can push that car at a certain top speed. Now if you
increase the drag coefficient by adding(lengthening) more spoiler or
increasing the angle of attack of the spoiler, that 550ft/lbs torque motor
will not push that car as fast. Because the drag on the car was
increased.Also increasing the amount of wind a spoiler displaces,
will(should) increase that cars "Sweet Spot".

Drafting: I waited to do drafting after drag, because you can't understand
one without understanding the other. In the description of drag, i
mentioned the displacement of fluid by a body moving through that fluid.
Now that air, that was split opens a "pocket" behind the car where there is
very little wind resistance. So the car driving behind the one in the lead
doesn't have to work as hard to get around the track.(NOTE: Drafting only
occurs at speeds of 70 mph or greater, unless your driving behind something
that displaces huge amounts of air, like a semi). So at tracks over one
mile is where most drafting occurs.

"Sweet Spots": This is the area around the car where the amount of
airflow is the greatest, thus the handling of the car can be changed by a
invasion of that area. At short tracks this is really not important, but
at anything over a mile.....watch out!!! If you watch racing even a
limited amount, sooner or later you see somebody get a run on another car,
and there is no contact between the two cars but the one following will
scoot up real close to the leader. Then BAM all of a sudden the car in the
lead spins out.The second car has offically invaded another cars space (And
you thought that was something that only people did). What happened was
the second cars windshield and roof line formed a bridge for the air to
"jump over" the first cars rear deck, therefore removing the air off the
rear spoiler decreasing the amount of downforce and traction that the
rearend was getting, which would make the lead car loose. But this only
happens in a cars "Sweet Spot". So your asking, how is this relevent to the
question??? If you change any body part on a race car you will effectively
change the "Sweet Spot" on the race car. The extra downforce might be
great at the little tracks, but at the big tracks......i don't know. There
might be adverse effects to enlarging the spoiler, which should directly
increase the "Sweet Spot".

Speed: Simple enough, or so you think. Fast speeds on a oval track are
acheived in a number of ways. I'll use Bristol as a example since it's
about as different from Talladega as you can get. (They embrace complete
different concepts to make the car produce good lap times) If your new to
racing and you don't know what Bristol is you'll have to use your
imagination. It's a .533 mile race track with 36 degree banking and racers
tend to leave with beat up cars, get the picture. Also while i'm thinking
about it, a race track has four corners for those readers that are new to
this. Anyway here comes the cars around turn 4, the pace car dives on to
the pit road, And the race leader starts accelerating, leading the pack
down the front stretch. As he gets close to the corner he applies the
brakes to dive into the corner (thats turn one)as he approaches the
apex(center of the corner) he starts getting back into the gas and
gradually accelerates the car through the rest of the turn (thats turn two)
until he reaches full throttle going down the back stretch. And so it goes
the same for turns 3 and 4, which brings you back to the front stretch.
And so just from reading the description you already know that the person
that waits the longest to brake, and is the first person back in the gas
will produce better lap times than the guy that brakes early and
accelerates late in the corner. But the problem with accelerating early in
the corner is the car will tend to swap ends on the driver, because of the
limited amount of traction that the tires give, along with the aerodynamic
lift of the car body which lightens the rearend even more. And so extra
"weight" is added to the rearend of the car by adding a rear spoiler, which
produces "downforce" on the rear of the car. So what i'm trying to say is
that the more rear spoiler length added to the rear of the car, produces
more downforce, which allows the driver to start accelerating sooner, which
will give him a higher top speed on the straights and therefore better lap
times. So More Downforce+ Earlier Acceleration=Higher Top
Speeds...........sometimes.

Handling: This is easy......The "feel" of the car to the driver,
depending on the action and reaction of the chassis and car body to the
contour of the race course and the input of the driver. Geewiz i wish
speed had been that simple.


Now where was i.........oh, your question

So at this moment your probably looking at the screen, like a monkey
trying to do a math problem :p ,
saying so what exactly is the answer???? There really isn't a cut and
dry answer. Will the extra 1/4" help or hurt the chevys, at the short
tracks, it will probably help, if used right. If they have to carry that
same height on the tracks over 1 mile, they might be hurting, from the
enlarged "sweet spots" as well as from the slower top speeds. Due to the
extra drag.

Oh well, thats what you get for asking such a open ended question. :)
But feel free to e-mail me with any questions. I can't promise anything.


.
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Travis
H-O-T Race Engineering.
.
.
Honest, Officer!!! I wasn't tailgating.......I was DRAFTING!!!
 

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Drive True
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Touché, ScoobyDo!

Yep I totally agree if it's functional sure...but lots of times the stuff I see out there is not...I've even seen double or triple wings! I'd think they'd increase drag more than anything else. What I'd like to see for a change is someone who marries form and function perfectly, and I haven't seen anything like that, not aftermarketwise, not on the street anyway. Of course, given that I did get the WRX spoiler on my car, I guess I lean more towards form than function. I'd like to see something that gives us both...the Prodrive wing I guess does grow on you, but it still bothers me that the height is the same height as the rearview mirror, sort of a negative on function to me...
 
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Discussion Starter #3
You have a good point about the rear view mirror visibility issues. How about an inexpensive, adjustable, removable, form-following-function rear spoiler/wing, wouldn't that be ideal? Easily removable that is, without leaving holes in the trunk for rain to leak through.
 

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Drive True
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Yeah that would be cool...something with release clips just like rally cars have on their hoods. The holes could be covered up with a small piece of sheet metal painted to match the hood of the car :)
 

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How about the Carbon Fiber STi wing? Its not removable, but its not nearly as high as the Prodrive wing. I think its more on par with the stock WRX wing height. Not only that, but it functions probably a ton better than most stock wings b/c it actually is an airfoil and not just a piece of material.
 

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Drive True
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I'd have to see it. If it looks like the WRX one, then cool. But it would only look good unpainted on a black car...
 

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91TB78

When you are responding to a new post the buttons just below the subject line there is one labled (Img) You can use that one to attach an image

Jared
 

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Drive True
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Another thing that bothers me about those wings...I see them on lowered cars and the drivers are usually just cruising around. So what good is the wing then?
 

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SnowbordrWRX said:
What I'd like to see for a change is someone who marries form and function perfectly...
Take a look at the G35 sedan/coupe or the 350Z equipped with Nissan's Zero-Lift Aero Package. I believe the aero kit comes on the Track Model Z, and available as options on the G35. Just what it sounds like: zero lift, at highway speeds, I guess. On the G35 coupe it's a $550 option, but they also make you get the $1000 power sunroof. What one has to do with the other, I don't know.

Anyway the point is it's functional, and anyone who doesn't think the G35 coupe is gorgeous must be blind.

Another note on functionality: Most of us have probably seen it already, but I read that the new bodywork on the STi "cut lift in half at both ends". If that's not function, I don't know what is. And that's with the tall spoiler. They may have been talking about the WRC prototype, but I don't think so. That gigantic wing is indeed functional.
 

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I'd have to see it. If it looks like the WRX one, then cool. But it would only look good unpainted on a black car...
Well, if you wanna see the wing I am talking about go to www.vividracing.com and check out bodykits, then click on STi brand..then scroll down. Its the carbon fiber one..let me know what you think. My wife thinks its ghetto.
 
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