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The science of managing airflow
plays a major role in racecar design and tuning because Champ Cars are highly
sophisticated aerodynamic devices. Areas of high and low pressure are carefully managed to
maximize downforce (to give a car grip) while minimizing drag (to maximize speed). You can
see the wings on the nose and the large wing at the rear of the car. Underneath, two large
grooves (like funnels cut in half) suck the car down on the track by creating a partial
vacuum under the car. This is generally referred to as "ground effects." Wind
tunnels play a key role in Champ Car design and evolution. |
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Mechanics can adjust a car's
handling by raising or lowering air pressure in the tires. Flex in the sidewall of a tire
acts like another spring in the suspension. Increasing the air pressure makes the overall
spring rate higher, while lowering the pressure will make it softer. This adjustment can
be made much more quickly and easily than changing a spring on a shock. |
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A mechanical linkage, one each
for the front and rear suspensions, that helps transfer more weight to the inside tires in
the corners and helps keep all four tires gripping the track. The driver adjusts the
anti-roll bars with levers in the cockpit. Also called a sway bar. |
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The geometric inside center
point of a corner. In racing, a driver will often use a "late apex," turning
into the corner a little later than normal in order to straighten out the last part of the
corner. This allows the driver to accelerate earlier and harder, gaining maximum speed
down the next straight. |
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A car running near the back of
the field. |
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The fireproof hood drivers wear
under their helmets to avoid burns to the face and neck. |
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On oval tracks, the corners are
often tilted inward to provide faster speeds. On some road courses, certain turns may
actually be banked outward, a very difficult type of corner known as
"off-camber." |
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This flag is waved by the
starter to signal a driver that he or she must immediately report to the pits for
consultation related to a dangerous mechanical condition or a driving infraction. Failure
to heed the flag can result in exclusion from the final results of the event. This flag
may also be displayed in a "furled" (rolled-up) manner as a warning. Corner
workers may also display a black flag if the session has been halted by the display of a
red flag by the starter. |
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This flag is displayed by corner
workers around the track to signal to a driver that a faster car is either approaching
(steady flag) or attempting a pass (waved flag). The driver being flagged has no
obligation to do anything other than be alert, maintain the racing line and avoid
intentionally obstructing the faster car. |
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The exterior of the car. The
bodywork is generally made from carbon fiber. The panels lift off in sections so mechanics
can get to mechanical components easily and quickly. Bodywork is carefully sculpted to
maximize aerodynamic efficiency. |
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In most cars, including street
cars, pressing on the brake pedal applies a little more force to the front brakes than the
rear. This is designed to take advantage of the fact that under braking, weight transfers
to the front of the car. With lots of weight on the front tires, the brakes can be applied
very hard without completely stopping the wheels from rotating ("locking the
wheels"). At the same time, the rear of the car tends to get lighter, so the rear
brakes must be engaged less than the fronts to avoid locking the rear wheels and possibly
losing control. In a racecar, brake bias is adjustable by the driver to compensate for
changing conditions, such as on a wet track where there is less weight transfer to the
front of the car under braking, or to adjust for a changing center of gravity as fuel is
burned off. |
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Brakes transform motion into
heat. The heat in the cast-iron rotors of a Champ Car can reach 5,000 degrees F. When the
fluid in the brake system exceeds its boiling point due to hard use, bubbles can form in
the brake lines and calipers. Since these bubbles can be squeezed smaller by pressure from
the brake pedal, the pedal tends to "go soft" and may even go to the floorboard
without the brakes working properly. |
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In shock absorbers, a bump
adjustment is a change to the dampening of the shock on the compression stroke. As a car
passes over a bump on the track, each wheel assembly rises up to pass over it. Without
compression dampening, the momentum of the wheel assembly would cause it to continue to
rise after the bump until the spring finally overcomes the inertia and pushes the wheel
back down. Since a tire can't do any work while in the air, bump dampening stops the
upward momentum and allows the tire to stay in constant contact with the pavement. Bump
adjustments also affect how the weight of the car shifts around during braking,
acceleration and cornering, known as "weight transfer." |
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Refers to changes in wheel
alignment (toe, camber and caster) as the wheel moves through the suspension range. Wheel
alignment is set with the car stationary, so bump steer affects must be properly
considered to ensure that suspension movement does not cause adverse changes in handling
or grip. |
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An element of chassis tuning.
Each tire can be tilted inward or outward depending on the track. The usual idea is to
tilt the top of the tire inward (negative camber) so that under cornering loads, the
entire surface of the tread is being used to the maximum. On oval tracks, because the car
only turns left, the left-side tires may be tilted outward (positive camber). Teams adjust
the camber setting based on reading tire temperatures across the surface of the tread,
with the goal of having equal temperatures on the inside, middle and outside edges. Equal
temperatures across the surface of the tire indicate the tire is being used to its maximum
capacity. |
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Carbon fiber is lighter than
aluminum, stronger than steel, and very expensive material. It's used to construct the
chassis of a modern Champ Car. Sheets of carbon fiber cloth are "laid up" like
fiberglass by an expert fabricator using a mold, and then heated and reheated for days in
an autoclave, a large, high-tech oven. |
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The acronym for Championship
Auto Racing Teams Inc. The organization owns and sanctions the FedEx Championship Series,
the Dayton Indy Lights Championship and the KOOL/Toyota Atlantic Championship. CART is a
publicly traded company on the New York Stock Exchange under the symbol "MPH." |
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Another measure of chassis
tuning related to the front wheels. The front wheels are attached to the suspension at the
top and bottom of the wheel assembly. The top attachment is typically set a little farther
back than the lower attachment, creating caster. The more caster used, the more the wheel
resists turning forces, providing stability. Too much caster makes it very difficult to
steer, and causes the tire camber to change significantly as the wheel is turned. Not
enough caster results in the front end "wandering," or trying to turn on its
own. |
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When the track is unsafe because
of an accident, debris or a sudden downpour, the officials may put the track under caution
by waving yellow flags at the starter stand and around the track. This brings out the pace
car to gather the field and lead them around at reduced speed until the track is safe for
a restart. |
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The basic structure of a car,
including the driver tub, gearbox and suspension. Engines are provided separately. There
are five chassis running in CART this year, three are designed and built in the U.K.
(Reynard, Lola and Penske) and two in California (Swift and Eagle). |
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This black-and-white checked
flag is the most famous in racing, signifying the end of the session or race. At the end
of a race, the first car to receive the checkered flag at the finish line is the winner. |
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A quick succession of sharp,
slow turns, usually intended to reduce straightaway speeds. |
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Any time cars are on the racing
surface, the chief steward is in charge of the entire facility. He is stationed in race
control with radio communications all around the circuit, and he also has at his disposal
a full bank of television monitors that give him a view of the entire circuit. |
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When a car is running by itself
on the track, it's in "clean air" because the air is not being disturbed by
other cars. |
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Tires are extremely important in
racing, with Firestone and Goodyear providing the rubber for CART. Compound refers to the
chemical composition of the rubber tread, which requires a balance between the conflicting
goals of traction (soft compound) and durability (hard compound). |
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This refers to the distribution
of a car's weight among the four wheels. Management of corner weights is very important to
handling. This weight is usually adjusted through raising and lowering each corner by
rotating a threaded spring perch on each shock absorber or at some other point in the
suspension linkage. |
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Recognized by their white
clothing, these volunteer workers will travel across the country at their own expense,
eating peanut butter sandwiches and sleeping in tents to provide flagging and marshalling
duties around the track. Their expertise is key to the tremendous safety record enjoyed by
CART, and the drivers waving to the corner workers at the end of an event is their
acknowledgement of the contribution these great people make. If you are interested in
getting involved, volunteering for training at club racing events around the country is a
great way to get immersed in the action. Contact the Sports Car Club of America at (303)
694-7222 for more information. |
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Acronym for "Data
Acquisition Geek," a computer expert who maintains a team's Data Acquisition system
and analyzes the data. |
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Teams use sophisticated sensors,
transmitters, computers and software to provide information on what the car and the driver
are doing. Everything from engine stress to the driver's heartbeat can be monitored. The
information is analyzed to improve handling, performance and even driver technique. Data
can be acquired by connecting a computer to the car or by wireless telemetry. |
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The bodywork at the rear
underside of the car that controls underbody airflow as it exits the back of the car. A
good diffuser generates significant downforce. |
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The rear wing of the car in
front tends to push the air higher, creating a very turbulent low-pressure area directly
behind the car. At high speeds, downforce can be disrupted by following closely behind
another car. A car following closely often will suffer understeer as a result of being in
this "dirty air." |
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Wings on a racing car are upside
down compared to an airplane wing. Instead of lifting the car, they press the car harder
onto the track, providing increased traction for braking, acceleration and cornering.
Downforce is also provided by the ground-effects tunnels underneath the car, creating a
vacuum that sucks the car to the track. A modern Champ Car provides so much downforce that
it could actually stick to the ceiling at just over 100 miles per hour. Increased
downforce also results in increased drag, which slows a car down, so it's a tradeoff. |
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A fast-moving car creates a
low-pressure area behind it, causing the air to try to move with the car. A car following
behind can take advantage of this low pressure as it actually sucks the car along faster,
known as "being in the slipstream." A savvy driver can either use the draft to
pass, or to lift off the gas slightly and conserve fuel. |
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A contraction of
"Dynamometer," an engine-testing device used in the shop that measures power and
simulates the loads and environment of a racing engine. |
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Champ Cars use engines from
Mercedes-Benz, Ford, Honda and Toyota. These tiny engines are 2.65-liter overhead-cam
turbocharged V-8s producing approximately 850 horsepower at 15,000 rpm. Teams lease their
engines from the manufacturers, who maintain them with a team of their own technicians at
the track and in their factories. Specific details of the engines are tightly guarded
secrets. |
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Flags signal drivers of events
or conditions.Green, white, white/red, black, checkered, blue, yellow, red and red/yellow
flags each have a different meaning. See each individual color for an explanation of what
each flag means. |
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If a driver locks a tire (brakes
so hard that the wheel stops turning), he'll grind a flat spot on the surface of the tire.
This causes vibration that can make the car almost undrivable. |
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Formula cars must fit within a
specific set of design rules or "formula." The formulas are usually quite
complex, but basic issues include minimum weight, engine displacement, vehicle dimensions,
wing sizes and placement, ground-effects tunnel size and configuration, tire and wheel
size, and safety considerations. |
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The transmission attached to the
rear of the engine. Champ Cars have "sequential" shift patterns, which is more
like a motorcycle gear change than the traditional "H" pattern on most street
cars. |
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The green flag is used by the
starter to signal drivers that the race is under way, either at the start of the event or
at the conclusion of a full-course yellow flag condition. Green flags are used by corner
workers on road courses to let drivers know that they have passed beyond a yellow flag
area and may resume passing. |
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The starting order of cars, as
determined by qualifying position. |
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see Line. |
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In airplanes, this refers to a
cushion of air that builds up as a plane nears the ground. In racecars, this refers to
artificially generated low-pressure areas underneath the car that help it adhere to the
ground. This is done by "tunnels' on each side of the bottom of the car, which start
off small near the front and gradually get bigger towards the rear, creating a vacuum as
the car moves forward using the ground as the fourth side of the tunnel. The
specifications of these ground effects tunnels are carefully monitored by CART. Rules
specify the dimensions of the tunnels and how high the outside edge of each tunnel must be
from the ground. The greater the gap between the tunnel side and the ground, the more air
escapes and the less downforce is generated. |
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On the front and rear wings
there are often small vertical strips along the trailing edges of the wings, set at 90
degrees to the plane of the wing. Because these strips greatly reduce turbulent air behind
the wing, they can add significant downforce with a minimal amount of drag. On the rear
wing, it can be easily exchanged for a different size during a pit stop. CART team owner
Dan Gurney is generally credited with creating this device, which is also known as a
"wickerbill." |
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A sharp, 180-degree turn. |
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A tire that has been heated up
through use and then cooled down has experienced one heat cycle. This often results in a
slight hardening of the tire compound, which can make the tire perform at a high level for
a longer period of time. See Scrubbed Tires. |
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A measure of an engine's maximum
output in terms of torque over a period of time. Champ Car is around 850hp, Indy Lights at
425hp and Atlantic is around 240hp. |
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The area inside the boundary of
the track. |
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A brand name for a certain type
of carbon fiber, used in everything from driver's helmets to bodywork to bulletproof vests
used by police. A very strong, expensive and lightweight material. |
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This term describes two things:
the absorbent powder used to soak up fluid spills on the track (often real kitty litter)
and the gravel runoff areas on the outside of many road course turns that help slow cars
that go off the track. |
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This is the quickest way around
a race circuit, taking advantage of braking, cornering and acceleration. For example, the
line for a typical right-handed corner would begin by lining up on the left side of the
approaching straight, braking hard, turning in all the way across the track to the inside
curb, and then unwinding the steering wheel on the exit to release the friction of the
turn, which takes the car back across the track to the outside again. The idea is to use
the maximum amount of arc possible to maintain the greatest speed through the corner. The
line is often visible due to the rubber laid down by cars, and interestingly is not the
shortest way around the track, just the fastest. |
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Same as Oversteer. Typically
describes a cornering condition where the rear tires lose adhesion before the front tires,
resulting in a car that feels like it wants to spin easily. This is one of the most
unpleasant sensations for a driver on the superspeedways because once the car goes, it's
almost impossible to catch. Solutions include adjustments to tire pressure, increasing the
angle of the rear wing for more rear downforce, adjusting the rear anti-roll bar setting
or spring rates in order to provide more grip, and reducing grip at the front by reducing
the front wing angle or stiffening the front anti-roll bar setting or spring rates. Here
is an easy way to remember whether a car is loose (oversteer) or tight (understeer): If
the front end hits the wall, it was understeer. If the rear end hits the wall, it was
oversteer. |
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Bits of rubber scrubbed off of
racing slicks while cornering. These small balls collect on the outside of the turn, and
if a car goes wide (into the marbles, or "the gray," referring to the lighter
appearance of an area covered with marbles), then much adhesion is lost. This often can
cause a car to understeer straight into the wall or off the track. With the tire
competition between Goodyear and Firestone leading to softer and softer tire compounds,
marbles are more of a problem. CART uses a jet engine mounted on the back of a truck to
blast marbles off the track. |
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A roughly 10 to 20 foot wide
strip between the track and the spectators where only CART officials and media personnel
with credentials issued by CART may stand while the cars are on the track. Usually it's
between fences and behind barriers, but it varies from track to track and at different
sections of the track. |
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A fire- and heat-resistant
material used to make driving suits, gloves, shoes, helmet liners, balaclavas and
underwear. Divers wear four or five layers of Nomex, including long underwear for complete
fire protection. When combined with fuel bladders that are resistant to breaking open in a
crash, the risk of fire has been greatly reduced over the last 20 years. Much of this
technology was developed for the military. |
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Refers to any type of racecar
that does not have enclosed wheels. CART, Formula Atlantic and Indy Lights are open-wheel
cars, as are the sprint cars, midgets and modifieds that run at local Saturday night
tracks all over North America. Stock cars and sports cars are typically based more closely
on production cars, with the wheels enclosed within fenders. |
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See Loose. |
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Some turns on road and street
courses are actually banked outward, which can make them very tricky to negotiate. This is
known as an off-camber turn. |
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The area where the team
transporters are parked, and where the teams work on cars between on-track sessions. In
CART, this area is usually accessible to the general public. |
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The area where cars come in for
fuel, tires, adjustments and repairs during on-track sessions. The name originated from
early racetracks, where the mechanics actually stood in a shallow pit where they could
duck if an out-of-control car came their way. Today, mechanics are protected by concrete
walls, and the pit lane is segregated from the actual racing surface. |
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This historic term refers to the
driver who starts at the front of the field on the inside of the front row by virtue of
the fastest qualifying time. The term originated at horse tracks, where many of the
original Champ Car races were held on dirt. The finish and distance markers of a horse
track are marked by poles set on the inside edge of the track. |
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The CART rulebook states,
"The allowable intake manifold pressure shall be limited to a maximum pressure of
forty (40) inches of mercury absolute." The more pressure, or boost, you have forcing
fuel and air into your engine, the more power your engine produces. To keep the playing
field even (and the manifold pressures within the rules), CART provides each team with a
manifold pressure relief, or pop-off valve, to put on top of their intake manifold. It's
called a pop-off valve because it makes a loud pop when it lets off excess pressure. The
effect is a sudden drop in horsepower. CART jealously guards these valves, and goes to
great lengths to make sure they are both accurate and consistent. Each day of practice,
qualifying and racing, CART officials pass out the pop-off valves to the teams and collect
them in the evening. |
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Same as Understeer or Tight.
Typically describes a cornering condition where the front tires lose adhesion before the
rear tires, resulting in a car that feels like it wants to go straight. Solutions include
adjustments to tire pressure; increasing the angle of the front wings to press the tires
harder to the ground; softening the front anti-roll bar setting or spring rates in order
to provide more grip; or by making changes to reduce grip at the rear. such as reducing
the rear wing angle or stiffening the rear anti-roll bar setting or spring rates. Here is
an easy way to remember whether a car is loose (oversteer) or tight (understeer): If the
front end hits the wall, it was understeer. If the rear end hits the wall, it was
oversteer. |
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Qualifying determines starting
positions, based on each driver's best lap time during the qualifying session or sessions.
Each car is timed, and the starting grid is determined by the order of fastest cars. For
road and street courses, the cars are on the track at the same time, which requires
careful management of track position in order to avoid being blocked by a slower car. For
oval events, qualifying is one car at a time, usually for two timed laps. |
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Treaded tires used on a wet
track. Also referred to as "Wets." |
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In shock absorbers, a rebound
adjustment is a change to the dampening of the shock on the expansion stroke. Without
rebound dampening, the car would tend to bounce as it passes over bumps on the track.
Rebound adjustments can also affect how the weight of the car shifts around during
braking, acceleration and cornering. |
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When displayed at the
start/finish line, a red flag signifies an immediate halt of the session due to a
dangerous condition such as a flooded track or a car blocking the track. Corner workers
around the track will display black flags when this happens, and all cars are required to
stop racing and slowly return to the pits. The lap in progress is discarded, and the field
reverts to the order of the previous lap when racing resumes. If the race has run more
that 50 percent of the laps, the chief steward has the option to declare a complete race
if track conditions are not expected to improve. If a race has run less than 50 percent,
it will be concluded on another date. |
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This striped flag is displayed
by corner workers to signify debris (oil, sand, water or some other substance) on the
track. |
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Modern engines are controlled by
electronic "mapping" software that controls things such as fuel consumption and
ignition timing. Rev limiting is used for two purposes: to keep the engine from exceeding
its maximum rotational speed and exploding into bits of very expensive shrapnel, and to
adhere to speed limit rules in the pit lane. Maximum rev limits are set by the engine
manufacturer, while the pit lane rev limiter is controlled by a pushbutton on the steering
wheel. |
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Height of the chassis above the
ground. Because of the relationship between the height of the ground-effect tunnels and
their performance, maintaining optimum ride height is an important facet of car setup and
design. However, it is hard to manage since the faster a car goes, the more the
aerodynamic effects press it to the ground. Many very complex methods are used to maintain
a consistent ride height. A Champ Car's ride height must be within two to three inches
above the ground. |
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Also known as Scuffed Tires,
which have a few laps on them to remove the outer sheen and provide more consistent
traction. See Heat Cycles. |
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There are a huge number of
variable adjustments to the suspension, tires, gears, engine, wings, brakes and virtually
every other piece of the car that can be moved or electronically altered. The idea is to
improve the handling and performance by making a car conform to a particular track,
temperature and even weather condition. The driver with the best setup is in a good
position to win. A driver with a less-than-perfect setup can sometimes "hustle the
car" and compensate for the deficiency, but most drivers perform at their utmost only
when the car is comfortable. |
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British term for crash or
accident. |
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A racing tire with no tread.
There is a misconception that the tread pattern of a tire provides traction. This is true
in dirt, snow or on wet pavement, but on dry pavement the maximum amount of "contact
patch" is desirable. |
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An acronym you may hear on the
in-car audio, referring to the electronic "Speed Limiter In Pitlane" device,
which automatically keeps the car at the pit lane speed limit by holding a button on the
steering wheel. |
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See Drafting. |
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Teams on an oval track will
usually have crew members on top of the grandstand where they can see the entire track and
warn drivers of an accident or advise them where to go in traffic. |
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A brand new tire, with the
manufacturer's sticker still on the "tread." |
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An acronym you may hear on the
in-car audio, referring to the electronic "Shift With Out a Lift" device, which
allows gear shifts without lifting off the throttle, making the shift faster. |
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A driver following closely
behind another car may dart momentarily to the inside at the entry to a corner, pretending
to attempt a pass in order to disrupt the concentration of the driver in front and
hopefully cause a small mistake, setting up a subsequent passing attempt. |
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Data acquisition transmitted
wirelessly while the car is on the track. |
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Braided Kevlar double strap
bolted to the wheel on one end and to the chassis on the other to keep the wheel attached
to the chassis in case of an accident. |
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See Push. |
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In order to provide stable
tracking, all four tires are usually pointed slightly inward if viewed from overhead. More
toe-in provides more stability but increased tire drag. On high-speed oval tracks, these
toe settings are even more crucial. Teams usually adjust toe with the most unsophisticated
methodology seen in racing, using a string around the outside of the car and a caliper to
measure the difference in the distance from the string between the front outside of the
tire and the rear outside of the tire. |
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A measure of engine power,
described in foot-pounds of force. 10 foot-pounds of torque would raise 10 pounds of
weight one foot in the air. Horsepower is a measurement of torque over a period of time. |
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Small blue electronic
transmitter mounted to the chassis. When the car crosses a wire embedded in the track, it
sends a signal to the CART Timing computer for lap and lap segments timing. Each car has a
specific code so the computer can keep track of the individual cars. |
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Ground-effect-generating venturi
underneath the side pods of a Champ Car. See Aerodynamics. |
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As a car reaches a corner, this
is the moment at which a driver actually begins to turn the wheel. The timing of this
action and the car's response to it are crucial for setting fast lap times. |
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See Push. |
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An area of revolving compressed
air. The most obvious examples are the vortices that are visible coming off the rear wing
of a Champ Car in humid conditions. These vortices are always there but only visible in
certain conditions. |
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When waved by the starter, this
signifies the start of the last lap of the race. When waved by a corner worker, it
signifies that a slow-moving vehicle is on the track. |
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Used by the starter, this white
flag with a diagonal red stripe indicates that an emergency or service vehicle is on the
track, and extreme caution should be used. |
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See Gurney Flap. |
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If displayed by a corner worker,
this means the subsequent section of the track has a problem that requires that drivers
slow down and not make any passes. Usually this is because a car has crashed and is in a
dangerous position. If the starter displays two yellow flags, it signifies a full-course
caution, which prompts the pace car to enter the track and lead the cars around at reduced
speed. |
