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Unless you are dealing with the kind
of power that smokes the tires (we're
not talking about lightly spinning them
in 4th gear, but real smoke-spewing,
unintentional-drifting-at-150mph-in-astraight-
line type power), a rear wing
will only slow you down.
A rear wing on a FWD car can only
be about looks on the street or strip;
make sure it comes off easily when
you get to the strip!
Choosing a body or wing kit that
allows easy removal or adjustment
will be the best option-some of the
kit and wing choices look great once
on a car, but aren't designed to be
easily worked with once bolted on.
Looks and styling are very much about
personal preferences, so while I can't
go into every kit available, we can
look at a few things to keep in mind.
Body kits are usually created
to generate impressive looks, not
impressive performance. This isn't a
bad thing, but for a car that lives on
the street and the strip, a compromise
between looking good when parked
on a corner and looking even better
with an NHRA *Wally* trophy perched
on the hood in Victory Circle is what
we'll strive for.
The average aftermarket
body kit wasn't designed by an
aerodynamicist, so using your best
judgment to evaluate a kit for its
attempts to mimic an SCCA World
Challenge or Japanese GT (JGTC)
car's appearance is a great first
start. Buying a racing magazine and
comparing the body you see wrapped
around the body of a big factory
team's drag racing car to the kit you
are considering is a cost effective way
of comparison shopping.
Those factory teams will spend over
$500,000 a year in aerodynamic wind
tunnel testing to develop their perfect
body shapes; for the big investment of
$5 on a drag magazine, you can save
the half million they spent, search for
a kit that is similar in concept to what
you see in those pages, and hit the
strip with a smart kit that will lend itself
to speed.
One thing to be mindful of is the size
and dimension of many of the rear
wings available for your car. In this
case, bigger isn't better.
The trick about wings that should
be understood is that they really
only produce noticeable downforce
above a certain speed. Leaving the
starting line, a rear wing, even an OEM
wing on a bone stock car, won't do a
thing to provide better traction. Once
you leave the line, and provided you
don't have trillions of HP, that wing
will only slow you down and keep you
from your best time through the traps.
So, knowing a rear wing won't do
much on the average import racer
with 500hp or less, removing it while
preparing to go from the street to
the strip is a smart move. Getting that
rear wing downforce and drag off the
car will help, but we need to look at
something to possibly put in its place.
Using a Subaru for example, the stock
wing on a STi will slow you down at the
strip, but just removing it altogether
might not be the best solution. Air
loves (and I mean LOVES) to lift up on
round surfaces. Without the wing on
the back of the STi to force the air up
and away from the shapely roof and
rear window, the lack of something on
the rear to spoil the air fl owing over it
will cause the wind rushing over your
car to pull the car upwards.
This dynamic, aptly named "Lift," is
great for a Boeing, but not a Subie.
If your car has a fairly well rounded
body top surface (more like a Beetle
than an xB), you'll need to look at
adding something to spoil the air fl ow
and lightly defl ect it upwards and
away from the roof and back window.
We're not looking for downforce here:
helping the air to fl ow over and away
smoothly without pushing down or
pulling up is the goal.
Allowing air to lift your car off the
ground, even just a little bit will take
enough weight off of your tires to
cause instability at anything over
moderate speeds.
If you've ever seen footage of a
Funny Car blowing over, it isn't the air
getting under the car that causes it to
leave the track; with the front of the
dragster coming off the ground, the
body loses all downforce and makes
it easy for the air to grab hold of the
pretty round curves and pull the car
skyward. Even in a stock Honda Civic,
we'll want to diminish Lift as much as
possible...
If I were to take a STi to the strip, I'd
replace the OEM wing with a standard
WRX spoiler, avoid the wasted
downforce and use the smaller WRX
appendage to be sure I avoid lift from
the roof and rear window.
For whatever you use on the street,
when it comes time to hit the strip, look
for a basic spoiler to replace your rear
wing and enjoy dropping anything
from a few hundredths to a few tenths
of a second, depending on what you
are driving.
Release the beast
Trapped air is unhappy air! The last
major area of finding speed through
aero efficiency is to look at the air
entering the engine bay and fender
wells. Since we're trying to make
the air that hits your car as happy as
can be, we need to consider what
happens to it when it passes through
a radiator or intercooler opening. That
air slams into a motor, pumps, pulleys,
and a ton of other solid objects before
ultimately smacking the fi rewall. Not
good, and not happy air. There really
aren't any easy exits for that air to
leave through.
To help solve some of this problem,
hood vents or louvers are quite
effective. Giving that grumpy air an
easy exit up and out from the engine
bay will help reduce turbulence and
drag. It will also help cooling and lessen
heat-soak--this aero trick has multiple
benefi ts. Many body kits, especially
carbon fi ber kits, offer hoods with a
variety of vents and louvers available
to select.
Louvers toward the front of a hood
are most helpful; placed at the back
of the hood (near the base of the
window) will actually cause the swirling
air at the base of the window to enter
the engine bay, thus defeating our
goal of extracting air to improve aero
effi ciency.
Another body kit purchasing
consideration is to select a vendor that
offers front fenders with louvers on the
tops of the fenders. Rushing air gets
trapped in the fender well without an
easy path to exit; with the incredibly
turbulent air that gets stirred up by
the spinning front wheels, fender-top
louvers set that trapped and turbulent
air free, making your air happy again
and your ride even faster.
For the art of tweaking your car to
look good on the street and save time
cutting through the air at the drag strip,
spending some time to focus on some
basic aerodynamic improvements will
distinguish you from your competitors.
If you need to shave time from your
runs, don't just look under the hood:
stand back and look at your car as a
whole-what tips and tricks can you
now use to free trapped air, remove
unneeded downforce, or diminish
aero drag that's holding you back?
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