[Shotimes] Do Air Dams, Spoilers, and Wings Work?
Kirk Doucette
Kirk.doucette@verizon.net
Sun, 13 Apr 2003 00:13:04 -0400
You just mad because yours is slow
Kirk J Doucette
NESHOC President
Stormtrooper-97 White
-----Original Message-----
From: Ian Fisher [mailto:ianf@eden.rutgers.edu]
Sent: Saturday, April 12, 2003 11:54 PM
To: 'Kirk Doucette'; shotimes@autox.team.net
Subject: RE: [Shotimes] Do Air Dams, Spoilers, and Wings Work?
What rumors?
I think that so many SHO's are out there in various states of tune and
disrepair that a comparison of any of the V6 mtx's against each other
isn't going to show that any year is really quantatively faster than
another..
Ian
-----Original Message-----
From: shotimes-admin@autox.team.net
[mailto:shotimes-admin@autox.team.net] On Behalf Of Kirk Doucette
Sent: Saturday, April 12, 2003 11:38 PM
To: Ron Porter; James F. Ryan III; shotimes@autox.team.net
Subject: RE: [Shotimes] Do Air Dams, Spoilers, and Wings Work?
Lat me ask you this, there are rumors about the 92's being faster. Could
it be because of the lack of the over hang from the wing on the sides?
Kirk J Doucette
NESHOC President
Stormtrooper-97 White
-----Original Message-----
From: shotimes-admin@autox.team.net
[mailto:shotimes-admin@autox.team.net]On
Behalf Of Ron Porter
Sent: Saturday, April 12, 2003 1:53 PM
To: James F. Ryan III; shotimes@autox.team.net
Subject: RE: [Shotimes] Do Air Dams, Spoilers, and Wings Work?
Since the spoilers on the '91 Plus through all of the Gen 2 SHOs is
barely more than an extension of the decklid, I don't believe that any
of them do anything practical (other than the Gen 2 holding the CHMSL!).
Ron Porter
-----Original Message-----
From: shotimes-admin@autox.team.net
[mailto:shotimes-admin@autox.team.net]On Behalf Of James F. Ryan III
Sent: Saturday, April 12, 2003 1:32 PM
To: 'Ron Porter'; shotimes@autox.team.net
Subject: RE: [Shotimes] Do Air Dams, Spoilers, and Wings Work?
> From: Ron Porter
> In this case, I believe that he is referring to the "skateboard"
> spoiler on the Gen 3, which supposedly has a real benefit at higher
> speeds.
That's what I figured since the article is from '98 and I remember
reading that (about the Gen3 skateboard) on the list a while back.
It's amazing that the big wing on the Superbird/Daytona only gave an
extra 5mph. If that's true then the spoiler on my '91+ doesn't do
squat. (I never thought it did anything anyhow.)
Jim Ryan
Wayne, NJ
'91 Plus - all white/mocha with fiberglass hood, rod shifter, & rear
spoiler
255 Lph fuel pump, SHO Shop can & horn, 80mm MAF, S&B cone filter, SHO
Shop HiFlow Y-pipe & cat-back exhaust, SHO Shop LPM, SHO Shop underdrive
pulleys, SHO Shop HiRevs Jr clutch & steel billet LiteWeight flywheel,
reinforced engine & trans mounts, SHO Shop TQ limiters, SHO NUT aluminum
SFBs, FPS '96 SHO front brakes, Carbotech F brake pads, Nook's full-body
SFCs, Koni adj struts, SHO Shop linear springs, 24mm FSB, 26mm RSB, SHO
Shop steel f&r STBs, Bridgestone Potenza RE-730 225/55-16, CATZ MSP fog
lights, police grille
> Sent: Saturday, April 12, 2003 1:15 PM
> To: shotimes@autox.team.net
> Subject: RE: [Shotimes] Do Air Dams, Spoilers, and Wings Work?
>
>
> Ron Porter
>
> -----Original Message-----
> From: shotimes-admin@autox.team.net
> [mailto:shotimes-admin@autox.team.net]On Behalf Of James F. Ryan III
> Sent: Saturday, April 12, 2003 11:28 AM
> To: shotimes@autox.team.net
> Subject: [Shotimes] Do Air Dams, Spoilers, and Wings Work?
>
>
> Found this excellent article on one of my Fiero sites. It's from Sept
> 98 issue of Car and Driver. It has excellent info AND mentions the
> SHO!!!
>
> Jim Ryan
> Wayne, NJ
> 91 Plus all white/mocha with fiberglass hood, rod shifter, & rear
> spoiler
>
> 255 Lph fuel pump, SHO Shop can & horn, 80mm MAF, S&B cone filter, SHO
> Shop HiFlow Y-pipe & cat-back exhaust, SHO Shop LPM, SHO Shop
> underdrive pulleys,
> SHO Shop HiRevs Jr clutch & steel billet LiteWeight flywheel,
reinforced
> engine & trans mounts, SHO Shop TQ limiters, SHO NUT aluminum SFBs,
FPS
> 96
> SHO front brakes, Carbotech F brake pads, Nooks full-body SFCs, Koni
adj
> struts, SHO Shop linear springs, 24mm FSB, 26mm RSB, SHO Shop steel
f&r
> STBs, Bridgestone Potenza RE-730 225/55-16, CATZ MSP fog lights,
police
> grille
>
>
>
> When we hear a posh English accent, we assume the speaker is
> intelligent. If we see food packaged in a green box labeled "Organic!"
> we assume it is healthful. Similarly, when we see a skirtlike air dam
> on the front of a car, or a wing or spoiler on it's rear deck, we
> presume it's a performance car. But do these devices in fact have an
> aerodynamic effect on
> production cars? Or are they no more functional then a vinyl roof?
They
> come
> in so many configurations and sizes, and on so many kinds of cars,
that
> it's
> easy to dismiss them as nothing more then eye candy. But that's not
always
> warranted, as we shall see.
> Aerodynamics is almost as much black art as it is science, and
problems
> that crop up when air is forced around an object are not easy to
fathom.
> As
> a car speeds down the road, for example, it creates a moving
obstruction
> in
> the atmosphere. Stationary molecules of air must move up, down, or
> sideways
> to flow around the car as it forges ahead. The air that ends up
underneath
> the car can be trapped by the various mechanical bits protruding from
a
> car's undercarriage and end up being dragged along by the moving car.
> That's
> how a car can pick up a scrap of paper as it passes over it and whisk
the
> paper along in its wake. Dragging this air along requires energy and
> comprises a large fraction of a car's aerodynamic drag.
> Moreover, the flow of air underneath the car can build pressure at
the
> front of the car and in the engine bay, lifting it upward, resulting
in
> less
> force pressing the tires to the pavement. That means less grip, which
can
> adversely affect handling.
> One way to attack these drag and lift problems is by creating a
smooth
> underbelly. That can be done by installing panels underneath the car
to
> reduce the likelihood of air being snagged and pressurized by
underbody
> protrusions. But today, only pricey mid- and rear-engined production
cars
> such as the Ferrari F355 and the Lotus Esprit use such panels because
of
> the
> cost of manufacturing and installing these parts, known as "belly
pans."
> A far more common solution is the front air dam, a rigid, skirtlike
> panel
> that extends below the front bumper. This dam diverts air upward over
the
> hood, or into a grille opening, or around the sides of the vehicle.
> At the rear of the car, the goal is to keep the air flowing smoothly
> over
> the body so that the hole the car punches through the atmosphere
closes as
> neatly as possible. Airflow that closely follows the contour of the
car is
> called "attached" or "laminar." The shape that best achieves this
laminar
> flow is the teardrop---the configuration formed by a drop of rain as
it
> falls through the air (round end first, for science philistines). GM's
> super-efficient EV1 electric car approximates this shape, but more
> conventional contours can also maintain laminar flow. The essential
> contour
> is a rear window that is sloped to within 25 or so degrees of
horizontal.
> Many hatchbacks are so designed, as are such cars as the Chevy
Corvette
> and
> the Toyota Supra.
> But keeping the air attached to the vehicle can present a different
set
> of
> challenges. When you observe such a hatchback car from the side, it is
> curved on top and flat on the bottom---like the cross section of an
> airplane
> wing. When air flows over a shape like this, the air must travel
faster
> over
> the top than over the bottom. This phenomenon produces lift and is
known
> as
> Bernoulli's principle, which maintains that a pressure drop must when
> airflow is accelerated. The pressure over the top of the car might be
only
> a
> fraction of a psi less than the pressure on the bottom, but that
> difference
> acts over a large area of the car---from 10 to 20 square feet. The
> pressure
> difference also increases with speed. Traveling at more then 100 mph
in
> some
> cars can produce hundreds of pounds of lift. Lift generated this way
> typically acts more on the rear of the car. But it has a similarly
> destabilizing effect on handling as front-end lift.
> Vehicles with more-vertical rear windows---such as formal sedans,
> wagons,
> and minivans---don't suffer from these lift problems as much, because
the
> air spills behind their more-upright rear windows in randomly tumbling
> eddy
> currents. This is what's known as turbulence, and although it limits
lift,
> it's a major contributor to drag.
> The middle ground between these two conditions---between 28 and 32
> degrees
> of backlight angle---is no solution, either. At this angle, the air
can't
> decide whether it should stay attached or become turbulent, so it does
> both
> unpredictably. Aerodynamicists are about as fond of this backlight
angle
> as
> they are of a vertical, flat windshield.
> Rear wings and spoilers were invented to address these lift and
airflow
> issues. Wings come in many shapes and sizes, but they share a common
> characteristic---a narrow, horizontal surface, mounted away from the
body
> in
> clean, undisturbed air. (Wings mounted close to the body are either
> nonfunctional or act more like spoilers, described below.) Wings add
> downforce---the opposite of lift. One way to create downforce is to
shape
> the wing into an airfoil---an airplane wing of sorts---and turn it
upside
> down. This forces the flow below the wing to travel at a higher
velocity
> then the air above, creating a downward force. A second way to create
such
> downforce is to angle the front of the wing slightly downward into the
> airflow. This creates more drag then a horizontal airfoil, but it can
> allow
> adjustability of the downforce.
> To differentiate a spoiler from a wing, think of turkey plumage. The
> spoiler is an angular, liplike appendage attached to, or designed
into,
> the
> rear of the car. It can be used to create downforce like a wing , but
it's
> more commonly used to reduce lift or drag. On hatchbacks, a lip
spoiler
> can
> create a pool of air ahead of the spoiler that separates the airflow
from
> the backlight, reducing lift. It can also be used at the rear of the
car
> to
> launch the airflow cleanly away from the vehicle, preventing its
tendency
> to
> remain attached to the car's trailing surfaces. This can decrease drag
as
> well as reduce the underbody pressure that contributes to lift.
> Automakers were hard at work on drag reduction as far back as the
1930s.
> It wasn't until the early 1960s, as both race-car and production-car
top
> speeds approached 200 mph, that lift became an issue. Ferrari racer
Richie
> Ginther is credited with inventing the rear spoiler for downforce in
1961,
> and discreet rear spoilers started appearing on competition Ferraris
soon
> thereafter. One of the first cars to use a front air dam was Ford's
GT40.
> The high snouts of early prototypes produced so much lift at 200 mph
that
> they were virtually undrivable. Fitting a air dam increased the force
on
> the
> front-tire contact patches from 310 pounds to 604 pounds at top speed.
The
> Dodge Charger Daytona and Plymouth Superbird twins of 1969-70 were
among
> the
>
> first production cars to sport a rear wing. The adjustable wing,
> supported high above the rear deck by finlike butresses, combined with
> changes to the nose of the car (including an air dam) to increase
> downforce at both ends of
> the car. This allowed test drivers to lap Daytona speedway 5 mph
faster.
> Porsche was probably more responsible then any other carmaker for
> turning
> air dams and spoilers into fashion statements. The 1975 Turbo's
integrated
> front air dam and huge whale-tail spoiler in back cut overall lift on
the
> cantankerously handling 911 by a whopping 90 percent. The
> air-dam-and-plumage look soon became synonymous with the prestigious
> Porsche
> brand. By the late 1970s, just about any car aspiring to a performance
> image
> wore some kind of air dam or spoiler.
> Today, air dams, spoilers, and wings can be found on such supercars
as
> the
> Dodge Viper GTS and Acura NSX, where you would expect them. But they
also
> adorn the exteriors of Dodge Neons, Toyota Corollas, Oldsmobile
Intrigues,
> and other sedans, many of which are not capable of speeds of much more
> than
> 100 mph.
> Which raises an important point; these aerodynamic devices don't do
much
> if your not going fast. Aerodynamic drag doesn't even exceed tire drag
> until
> you've reached 40 to 50 mph, and you may have to be doing well over
100
> mph
> for spoilers and wings to have any appreciable effect on lift or
> downforce.
> This is because aerodynamic forces vary with the square of a car from
80
> to
> 160 mph, and if faces a four-fold increase in lift and drag forces.
> Nearly all cars can benefit from the drag-reducing effects of an
air-
> dam.
> The Pontiac Grand Prix sedan's front air dam, for example, reduces
that
> car's overall drag by 5 to 10 percent. Front air dams also help with
> engine
> cooling and can even serve as a useful place to mount fog lights.
> Carmakers don't deny, though, that rear wings and spoilers are often
> more
> show than go. At GM, spoilers are usually added as a marketing-driven
item
> at the beginning of a car's development, according to John Plonka, an
> aerodynamics-development engineer at the company. "From there, we take
> those
> pieces and try to make them aerodynamically useful, with varying
success,"
> he adds. John Doughty, chief designer of Ford's Advanced Design
Studio,
> describes a similar story but adds that "if we found that it detracted
> from
> the performance, we wouldn't recommend it." Perhaps such a
recommendation
> was made, but not heeded, on the Ford Mustang Cobra.
> Some carmakers would rather not install spoilers but offer them
simply
> because car buyers demand them. "Personally, it hurts to see a Camry
with
> a
> [nonfunctioning] spoiler on the back," says Donald W. Brown, former
> national
> product-planning manager for Toyota in the U.S., "but if the dealers
are
> going to put them on anyway, we would rather supply them to ensure
their
> compatibility with the car."
> That doesn't mean these devices are never beneficial to workaday
cars.
> Brown notes that the factory rear spoiler on the Lexus SC trims its
> coefficient drag from 0.32 to 0.31, and Ford's Doughty notes a similar
> improvement with the rear wing of the Ford Taurus SHO. A future Ford
> economy
> car might end up with a rear spoiler solely for fuel-economy reasons,
says
> Doughty.
> So, it appears that front air dams are usually functional, whereas
rear
> wings and spoilers are as often functional as they are frivolous. Ford
> Advanced Studio designer Grant Garrison sums it up this way: "If wings
and
> spoilers weren't popular, we wouldn't put them on cars. We'd find some
> other
> way to make them aerodynamic."
> In other words, if wings and spoilers are what car buyers want,
that's
> what they'll get. Whether they work or not.
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