The following is FYI (from swrt).

Best regards.

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Facts & Figures

Some interesting facts and stats from inside the Subaru World Rally Team, and what it takes to compete in the World Rally Championship:

Engine
The two litre four-cylinder boxer engine in the Subaru WRC2007 produces around 700Nm of torque. Coupled to the stop-start nature of rallying, the clutch has to be twice the size of those used in Formula One cars so as not to burn out. Made of three plates of carbon, it measures 10” across.

The engine has a flat-four configuration, meaning that the cylinders are horizontally opposed. It uses an IHI turbo fitted with an FIA regulation 34mm air restrictor, which limits power to around 300bhp under FIA regulations. It can still propel the WRC2007 from rest to 60mph in fewer than three seconds.

Each engine takes 75 hours to hand build at the team’s base in Banbury, and costs £70,000. It contains more than 900 individual components. A rebuild comes after approximately 750km or two rallies, although in some instances a pair of engines must be nominated for a group of three rallies.


Drivetrain
The Subaru World Rally Team has produced 111 WRC gearboxes since 1999. By the end of the 2007 season, 48 WRC differentials will have been built since 2004.

Each gearbox takes 85 hours to build and costs £75,000. Coupled with the rear differential the transmission system contains over 700 individual components.

Once a unit has been build, it takes three hours for the team’s dyno to run through the complete test procedure before it is used in one of the Imprezas.

There are two special insulation panels fitted to the side of the gearbox to shield it from the heat of the exhaust which runs alongside it. Each plate is made from titanium and ceramic coated, using a process designed for space craft.

Removing the gearbox requires undoing just 12 bolts to disconnect the propshaft, the drive shafts and separate the box from the engine. There is also one wiring loom connector that links the electrical gear shift mechanism to the ECU.

The engine, gearbox and differential are all individually oil sealed, meaning that each can be removed and replaced without fluid loss.

The gearbox contains two separate oil systems – one for lubrication and one hydraulic system for shifting gears. The lubrication system has a capacity of 4.5l and is fitted with an oil pump that flows 12l a minute to keep temperatures down. The gear shift system operates at a pressure of 150bar, or 2,500psi for almost instantaneous shifts.

Each unit uses over 40 specialised oil line connectors. Approximately half of these are built specifically for the Subaru World Rally Team, and all are aircraft grade.

The gearbox retains the road car’s H pattern but uses a hydraulically and electronically controlled gear change system to shift each gear in fewer than 0.1seconds.

Undergoing 3500 gear shifts on every rally, each unit is rebuilt after approximately 750km of competitive use or two rallies. The oil is changed for every rally.

The gearbox and differential run at 100 degrees Celsius, and need their own oil coolers to maintain that temperature. On hot rallies such as Greece, the operating temperatures can reach 120 degrees Celsius.

It takes between 10 – 12 minutes to replace a gearbox and rear differential. The fastest time on a rally was 10mins and 20 seconds set during Rally Deutschland 2007.

The housings of both units are cast from magnesium for strength and to reduce weight. A gearbox weights 95kg when wet (full of oil) and a differential 25kg wet.

Each differential takes 16 hours to build, and costs £20,000. The front and rear differentials share components to reduce costs, whereas the centre differential is unique.

Depending on driver preference, each differential contains up to eight four inch diameter steel friction discs. Each disc has six carbon fibre patches bonded to it to increase friction and prolong life. Increasing the number of discs increases the power which the diff will handle before slipping.


Body
The body is received as a bare shell from the Subaru road car production facility in Japan. SWRT technicians strip it of all excess weight and unnecessary mountings and brackets, install stronger suspension turrets, enlarged wheel arches, the roll cage, a custom transmission tunnel and the jacking points in the door sills that are used to keep the car raised during service.

The body shells are supplied with a coating of zinc, used in the road versions to protect from rust and corrosion. An acid bath is used to remove this zinc from the body, lightening the shell by 8kg.

Each WRC body shell takes 740 man-hours to build, before it is ready for painting. To get to the stage of a complete ready-to-run WRC car takes a total of 1500 hours.

If all of the T-45 grade high carbon lightweight steel tubing that forms the roll cage was laid out it would stretch for 75 metres.

Each shell costs in the region of £38,000, taking into account labour and all the associated materials used for the modifications over the standard body shell.

Once complete, the body shell of the Subaru Impreza WRC2007 is so strong that it will support the weight of ten identical cars.

During very hot rallies, such as Greece white vinyl squares are stuck to the roof of the cars to reflect heat from the cockpit, reducing temperatures inside. Reflective film is stuck on the inside of the side windows for the same purpose.

The large rear spoiler and splitter on the front bumper control the car’s pitch when airborne, after a jump for example. Without these, the nose of the car will dip and the rear will climb, a motion known as pitch.

As a rally car spends most of its time on a stage sliding, the vertical fins of the rear wing have been designed to control the yaw angle. This is the movement of the car about the vertical axis, the effects of which can cause the car to spin.

In the Impreza WRC2007, the co-driver’s seat is mounted between six to eight inches further back and 10 inches lower than the driver in order to optimise the weight distribution and centre of gravity of the car.

Using only two seats for the driver and co-driver only, they are specially moulded from carbon-fibre. Weighing only 5.2kg each, they are incredibly strong and could support the weight of ten men.

The bumpers are lightweight items made from a strong carbon-fibre and Kevlar construction. Weighing just 3kg, a single item costs £2,500.


Suspension
The dampers are changed for asphalt and gravel rallies; on asphalt the cars run 70-75mm lower than on gravel, and due to the smoothness of the surface the suspension is set more stiffly, minimising body roll and allowing the cars to carry more speed through the corners.

Strong lightweight materials such as titanium are used extensively in the Impreza’s hubs, uprights, and dampers to withstand the demanding terrain of events like the Acropolis Rally of Greece.

Using a MacPherson strut system at the front and MacPherson strut with longitudinal and transverse link at the rear, the Impreza’s overall set up is almost endlessly tuneable so it can be adapted for each round of the WRC.

Each corner of the Subaru Impreza WRC2007 (the complete shock absorber and brake assembly) costs around £27,000, or more expensive than the price of a new Impreza WRX road car.


Electrical
The engine wiring looms are built from aerospace grade wiring. At an average cost of £6,000, these cutting-edge materials allow the loom to weigh half that of a road car equivalent.

The connectors that are used to join looms to the ECU and various data logging sensors are specifically designed. Manufactured to aerospace grade, they are both water and heat resistant.

They consist of very low resistance multiple pin connectors housed within an insulated alloy case. This allows complex and high current circuits to be joined reliably and safely.

Unlike road car connectors, the male and female blocks are threaded, so once mated they can be tightened together. This makes the seal water resistant, and able to cope with the shocks and demands of rally stages.

Insulating sleeves are used to seal the wires as they enter the back of each connector block. Placed over the wires and the lower portion of the connector block, the sleeve shrinks when heat is applied by a heat gun, closing tight onto the loom to seal it tight.

The alternator produces 200amps, approximately twice that of a standard road car. There are 20 separate circuit breakers throughout the wiring loom to protect the systems in the case of a problem.


Wheels and tyres
Different road conditions call for different suspension and tyre setups, and even different size wheels. For gravel, 15in wheels are used, 16in for snow and 18in for tarmac.

Made of forged aluminium, the 18-inch wheels designed for asphalt use weigh 7.9 kg and cost approximately £300 each.

The same tyre pressures are used for both asphalt and gravel, and are set at 1.8bar, equivalent to 30psi.

Currently all the BFGoodrich tyres used by the Subaru World Rally Team contain a specially designed run-flat mousse which protects the tyre from punctures and resulting delamination. This will cease next year when the system becomes banned after the switch to Pirelli control tyres.

When tyres are fitted to wheels, they are inflated to a pressure of 2bar and loaded in batches into mobile air-heater units, in which they are kept at 55 degrees Celsius for an hour to seal the bead.

Once removed, they undergo a process of being pumped to 4bar and then deflated four times over. This removes all moisture and condensation inside the tyres, at which point they are inflated with carbon dioxide to a pressure of 2bar ready for use.


Brakes
On asphalt rallies, the cars use AP racing 366mm brake discs and eight-pot callipers. On gravel 305mm discs and four-pot callipers are employed as the level of available grip is reduced and the wheels smaller.

Water jets are used to cool the front brakes on asphalt rallies, where disc and pad temperatures can reach 860 degrees Celsius.

The brake fluid operating temperature is typically between 100 and 120 degrees Celsius.


The team
On an average rally there will be 60 crew on-event. This is made up of four team management, six drivers and co-drivers, five catering crew, five vehicle logistics crew, 25 technicians, ten engineers, one doctor, two PR crew, an IT technician and an assistant to the drivers.

During each service on a rally, a maximum of six team personnel are allowed to work on their car at any one time. These designated team members must wear orange armbands at all times. In addition, there are two ‘floating’ orange bands which are shared between technicians and can be used on any car.

The two servers and 20 laptops setup to form the team’s on-event IT network mean that over 1000ft of network cable is required at every European rally. And this is with the use of wireless access for all laptops.

The team vehicles taken to a typical European event consist of three crew cars, six service park vehicles, 16 auxiliary vehicles, four recce cars, and a forklift alongside the three 36 tonne trucks. In total, the team has over 40 tonnes of equipment to transport.

It takes a team of five people three days to assemble Subaru’s service area, and seven hours to completely disassemble the awnings.

The team’s base in the service park at each rally would fill the floor area of more than one quarter of a football pitch, with a total area of 360metres squared.

During a rally weekend, the team will consume a total of 180 meals a day, or over 1000 across the six days from the start of the recce to the finish of the event. In addition, the catering team can provide over 1100 meals for guests during the three days of competition.

Over a rally weekend, the team can consume twice the body weight of Peter Solberg in pasta!


Servicing durations
The time required for removal and replacement of each item:
Engine 40 minutes
Gearbox 10-12 minutes
Front corner (suspension and brake assembly) 8 minutes
Rear corner 8 minutes
Rear differential 14 minutes
Turbocharger 10 minutes
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