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| A race car with air conditioning? ALMS rules require a sealed cabin and a max temperature of 90 degrees F. The car’s air conditioning system has a complicated control strategy controlled by the engine’s ECU. |
Power from the engine is transferred down the drivetrain by a 6 plate 150mm AP carbon carbon clutch. A carbon carbon clutch has both the drive plates and the driven floating plates made from carbon. The small diameter gives a lower moment of inertia for faster throttle response and shifting. The multiple plates give the clutch enough friction material surface area to handle the engine’s torque.
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| The all important electronics. The electronics are pretty close to production stuff and are supplied by BMW AG. You can see boxes for telemetry transmission, engine control and various other functions. The fire bottle is installed near the electronics. The steering wheel has many switches for engine map selection and traction control as well as a bunch of other things we could not identify in our brief look around. The steering wheel looks sort of like the Mach V. Note the lack of gauges. When you are in radio communication with a room of German engineers watching everything for you on computer monitors, I guess you don’t need much in the way of gauges. |
To try to hit the target 50/50 weight distribution, the car has a rear mounted transaxle instead of an engine mounted transmission. The 6 speed transaxle is made by Xtrac, maker of things ultra trick in the drivetrain world. The transaxle features constant mesh dog engagement and sequential shifting. The transmission communicates with the engine via the CANBUS and uses a no lift to shift engine control strategy where the engine’s torque output is interrupted when the shifter is moved for ultra fast shifting.
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| The cage has a pretty advanced feature. In a severe accident the carbon roof is designed to be quickly and easily detached by rescue personnel. The top part of the cage can be detached by unscrewing these Allen screws. The seat is designed to contain and protect the driver like a huge carbon fiber helmet. The seat can be quick released and the driver lifted up and out through the roof. The seat can function as a gurney and the driver can be transported to the hospital strapped securely in the seat. In this pic you can see the carbon steering column finisher and the digital dash display. |
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| A closer view of the seat, look how thick the carbon is. |
The transaxle has a pretty interesting differential. It combines a Salisbury clutch type differential with a viscous unit. The initial lock and a flat percentage of lock are controlled by the viscous unit. The clutch side features tuneability via negative springs and cross shaft ramp shape for adjustability much like an OS Giken differential. Another interesting thing is that the engine’s accessory drives are taken up from the rear transaxle. The alternator, air conditioning and power steering pumps are rear mounted with power take up in the transaxle. This improves weight distribution and reduces parasitic power losses.
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| The carbon hood has exit vents for the hot radiator air. Top exit is good for drag reduction and helps generate downforce. These carbon ducts travel the whole length of the car and feed heat exchangers in the rear of the car. |
You heard right, the M3 has air conditioning. ALMS rules require sealed cabins for safety and the cabin temperature cannot exceed 32 degrees C. The air conditioning system is controlled by the Power 400 engine management system and is designed to at first only come on under lift throttle and deceleration. If more cabin cooling is needed, the air conditioning will then come on in the higher gears as well. It will only continuously run under the most trying conditions.
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| The carbon doors are super light and have these Kevlar and foam impact attenuators to help protect in the case of side impact. |
