Pit strategy

In any racing series that permits scheduled pit stops, pit strategy becomes one of the most important features of the race; this is because a race car travelling at 100 miles per hour (160 kilometers per hour) will travel approximately 150 feet (45 meters) per second. During a ten-second pit stop, all of a car's competitors will gain approximately one-quarter mile (one-half kilometer) over the stopped car.

However, the car that made the additional pit stop will run faster on the race track than cars that did not make the stop, both because it can carry a smaller amount, and thus lower weight, of fuel, and will also have less wear on its tires, providing more traction and allowing higher speeds in the corners. In racing series where teams have their choice of different compound tires, the lower tire wear may be enough to allow the team to choose to use a tire with a softer rubber compound that provides increased grip at the expense of faster wear; going longer between stops may even cause enough wear on the softer tire to cause the tires to fail.

Because of this, race teams plan a pit strategy prior to the start of every race. This is a schedule for each car's planned pit stops during the race, and takes into account factors such as rate of fuel consumption, weight of fuel, cornering speed with each available tire compound, rate of tire wear, the effect of tire wear on cornering speed, the length of pit road and the track's pit road speed limit, and even expected changes in weather and lighting conditions. The pit strategy does not just include a schedule of when pit stops will happen; it also includes what service and adjustments are scheduled for each pit stop, particularly in endurance racing, where scheduled changes of wear-limited parts such as brake pads may be planned for specific points during the race. The pit strategy is calculated carefully so that the amount of time to be "given away" to other competitors in pit stops is balanced out by the time gained while on the track, resulting, theoretically, in the shortest possible time to cover the scheduled distance.

However, a team's pit strategy is not a fixed, immutable thing; it is subject to change during the race to take into account the unpredictable events that happen in every race. In road racing, for example, if the weather changes from dry to rain, teams will be forced to recalculate their pit strategy based on the unscheduled stop to change from dry-weather "slick" tires to treaded wet-weather tires. Full-course caution periods often see mass pit stops by many teams, hoping to take advantage of the slowed pace to reduce the ground lost to other teams while making pit stops; this forces teams that do so to immediately recalculate their pit strategy to optimize it for the remaining race distance after the stop.

Even when a team chooses not to take advantage of the opportunity to stop during a full-course caution, it can still result in significant changes to pit strategy; under caution, the cars run at a reduced speed that results in greatly reduced tire wear and fuel burn for a distance traveled. Depending on the circumstances, this may be enough for a team to gain more by choosing not to pit, hoping that the reduced fuel burn and tire wear will allow them to make one pit stop fewer than the other teams, allowing them to gain distance and time on their opponents. At tracks noted for frequent full-course cautions, teams may even plan their entire race strategy around this, using a suspension and aerodynamic setup suited to short sprints instead of extended runs to gain positions in the short bursts of green-flag racing, and planning their pit strategy on the assumption that cautions will extend their fuel mileage and tire wear enough to make fewer stops than would otherwise be needed to complete the race distance.

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wiring your source unit

TOOLS REQUIRED: Phillips head screwdriver, Side cutters, Electrical tape, Soldering iron, Multi-meter INSTALLATION TIME: 30 minutes DIFFICULTY: Easy


STEP 1:

THE STOCK LOOM
FOR this installation I will assume that your car's loom will need to be cut into to adapt it to the new loom for a CD tuner. Once you've unwired the old source and cut away the factory connector plug you'll be left with a bunch of coloured wires. At this stage it's worth making a judgment on the space you've got behind the dash and to trim down both the stock loom and the one supplied with your source to cut down on cluttering.

STEP 2:
IDENTIFYING WIRES
THE stock loom will include wires that provide permanent power, accessory power, earth, a pair of wires for each pair of speakers in the system, and possibly dimmer and power antenna wires-often these will be arranged in logical paired fashion. Begin by stripping back a small length off each wire making sure that they don't touch each other. With the multimeter set to DC volts and touching the black negative probe to somewhere on the chassis you can easily find permanent power using the red probe and checking for 12-volts on the display. This wire will connect to the fused yellow wire from the new loom.

STEP 3:
FINDING ACCESSORY POWER
NOW turn the key to the 'accessory' (ACC) position and use the same technique to probe for switched accessory power, which is used to turn the source unit on and off when you to turn the key. This wire will connect to the red wire from your new loom. As an option, you could alternatively connect this wire from the sources loom to the permanent power lead, which will allow the system to be played independently of the ignition.

STEP 4:
FINDING AN EARTH
IT IS now possible to use the permanent power wire touched to the red probe and use the black probe to find the factory earth wire. I prefer to create a new earth to somewhere on the chassis behind the dash, as in some cars the stock wiring my give a false earth reading for things like the power antenna wire-causing a short circuit and lots of head scratching when you power up the source later on! There will be numerous screws or bolts behind the dash to use for the earth position.

STEP 5:
IDENTIFYING SPEAKER WIRES
THE speaker wires will be arranged in logical pairs on the stock loom. Begin by looking at the rear of one of the factory speakers connected in the car, as this will give you a guide as to the colours and phase connections to each speaker. Typically a trace will be used on one of the wires to each pair of speakers-denoting either positive or negative. You will need to take care to ensure all the speakers are wired in phase otherwise the system will sound odd.

STEP 6:
IDENTIFYING DIMMER & POWER ANTENNA TRIGGER
SOME aftermarket sources feature a dimming function that dims the display when the dash lights are switched on, and if your car supports this feature you can switch on your dash lights and probe for a9-12V signal from the reamaining wires on the stock loom. Power antennas also require a signal from your source to operate, and after you've identified all previous wires this should be the sole remaining wire on the loom. You can double check its colour by looking at the power antenna loom at the rear of the car.

STEP 7:
RCA & TRIGGER
IF YOU are using an external amplifier you'll have run RCA music signal leads and a trigger wire behind the dash from the amp's location. The trigger wire is the blue wire on the source's loom, though some sources feature separate triggers for external components and the power antenna, so this or your amp will only work when the radio is selected.

STEP 8:
SOLDERING WIRES
BEFORE I solder any wires, I test that all the connections are working properly and the unit retains radio station memory, the amplifier turns on, speakers are properly located for balance and fader, and the power antenna works. When soldering you should heat the wiring joint and let the solder soak all the way through the wire. Once this is done, a liberal wrap in quality electrical tape (the stretchy Nitto stuff is the best!) that runs 1 cm past either end of the joint will avoid short circuits.

STEP 9:
COMPLETION
WITH the loom plugged back into the new source you can now replace the source and finish up. The most challenging part of the job is often to fit the new loom and associated wires back into the dash aperture, which in many cars is fairly cramped. It's at this stage that you'll be glad you trimmed off all the excess wiring from the loom!