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Aerodynamics
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. Air pressure 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.
Anti-roll bar
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.
Apex
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.
Backmarker
A car running near the back of the field.
Balaclava
The fireproof hood drivers wear under their helmets to avoid burns to the face and neck.
Banking
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."
Black flag
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.
Blue flag
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.
Bodywork
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.
Brake bias
In most cars, including street cars, pressing on the brake pedal applies a little a 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.
Brake fade
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.
Bump
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."
Bump Steer
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.
Camber
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.
Carbon fiber
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 mould, and then heated and reheated for days in an autoclave, a large, high-tech oven.
CART
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."
Caster
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.
Caution Period
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.
Chassis
The basic structure of a car, including the driver tub, gearbox and suspension. Engines are provided separately. There are two chassis running in CART this year and are designed and built in the U.K. (Reynard and Lola).
Checkered Flag
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.
Chicane
A quick succession of sharp, slow turns, usually intended to reduce straightaway speeds.
Chief Steward
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.
Clean Air
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. See Dirty air.
Compound
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).
Corner Weights
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.
Corner Worker
Otherwise known as a marshal. The unpaid volunteers that work so hard at race meetings and with whom no race meeting could take place.
DAG
Acronym for "Data Acquisition Geek," a computer expert who maintains a team's Data Acquisition system and analyses the data.
Data Acquisition
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 analysed to improve handling, performance and even driver technique. Data can be acquired by connecting a computer to the car or by wireless telemetry.
Diffuser
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.
Dirty Air
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."
Downforce
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.
Drafting
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.
Dyno
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.
Engine
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.
Flags
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.
Flat Spot
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.
Formula Car
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.
Gearbox
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.
Green Flag
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 marshals on road courses to let drivers know that they have passed beyond a yellow flag area and may resume passing.
Ground Effects
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.
Gurney Flap
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."
Hairpin
A sharp, 180-degree turn.
Heat Cycle
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.
Horsepower
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.
Infield
The area inside the boundary of the track.
Kevlar
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.
Kitty Litter
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.
Line
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.
Loose
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.
Marbles
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.
No Man's Land
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.
Nomex
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.
Open Wheel
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.
Oversteer
See Loose
Off-Camber
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.
Paddock
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.
Pits
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.
Pole
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.
Pop-Off Valve
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.
Push
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.
Qualifying
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.
Rebound
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.
Red Flag
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.
Red and Yellow Flag
This striped flag is displayed by marshals to signify debris (oil, sand, water or some other substance) on the track.
Rev Limiter
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.
Ride Height
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.
Scrubbed Tires
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.
Setup
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.
Shunt
British term for crash or accident.
Slicks
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.
SLIP
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.
Slipstream
See Drafting
Spotters
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.
Stickers
A brand new tire, with the manufacturer's sticker still on the "tread."
SWOL
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.
Take A Look
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.
Telemetry
Data acquisition transmitted wirelessly while the car is on the track.
Tether
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.
Tight
See Push
Timing box
Small blue electronic transmitter mounted to the chassis. When the car crosses a wire embedded in the track, it sends a signal to the Omega computer for lap and lap segments timing. Each car has a specific code so the computer can keep track of the individual cars.
Toe
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.
Torque
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.
Tunnels
Ground-effect-generating venturi underneath the side pods of a Champ Car. See Aerodynamics.
Turn In
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.
Understeer
See Push
Vortex
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.
White Flag
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.
White And Red Flag
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.
Wickerbill
See Gurney Flap
Yellow Flag
If displayed by a marshal, 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.
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