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Getting Power To All Four Wheels

2013 Nissan GT-R Black Edition: The Gran Turismo Car
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Driving the GT-R's four wheels is Nissan’s Advanced Total Traction Engineering System for All-Terrain Electronic Torque Split (ATTESSA E-TS) system. While previous-gen Skylines, including the first AWD R32 GT-R, featured ATTESSA E-TS, the 2013 GT-R's implementation is vastly different, exclusive to the vehicle, and very technologically-complex. Understandably, Nissan wants to protect the inner electronic workings of its ATTESSA E-TS system. But the company did divulge quite a bit of information to us.

The GT-R's drivetrain isn’t conventional in the sense that it mates the engine to the transmission up front, sending power to the wheels from there. Instead, we have a rear-mounted transmission for optimal weight distribution and handling. But because this is an AWD car, things get more complicated. In addition to the drive shaft that connects the engine to the transmission, a second drive shaft runs parallel to the main one, tasked with powering the front wheels. The rear wheels have a limited-slip differential, while the front has an open differential.

Despite (or perhaps thanks to) the complicated setup, the car can split torque from 0:100 to 50:50, with a bias towards the rear wheels. Torque distribution varies based on the vehicle’s speed, lateral acceleration, steering angles, tire traction, road surfaces, and yaw rate. There’s an added bit of science in the yaw-rate feedback control that’s exclusive to the GT-R too: the car's computer calculates the differences between the target yaw rate (calculated from the steering angle) and actual yaw rate to adjust torque bias accordingly. If you’re unsure what yaw is, just imagine the accelerometer in your smartphone; that's essentially what the GT-R's yaw-rate sensor is measuring.

Adding to the complexity is a separate ECU just for the ATTESSA E-TS system. The ECU constantly reads data from the ABS sensor at each wheel, a three-axis g-force sensor, transmission sensor, and engine ECU sensors for maximum control of power distribution across all four wheels, purportedly yielding faster reaction driving conditions. Nissan won't comment on the ATTESSA E-TS ECU's polling rates, but does acknowledge that it "needs to be extremely fast to work at top efficiency."

The transmission is a six-speed dual-clutch unit with a wet multi-plate clutch system. Essentially, it’s a very complicated manual transmission without a third pedal, but capable of shifting much faster than a human.

Control of the drivetrain is handled by a drive-by-wire gas pedal. Nissan claims the electronic input from this subsystem will always be faster than a mechanical input, improving NVH (noise, vibration, and harshness) and reducing weight in the process, too. We had no complaints about the drive-by-wire throttle response; every time we pressed the pedal, our faces lit up (as I'm sure you can imagine).

Just when you thought the GT-R couldn’t get any more complicated, we move on to the suspension. Godzilla relies on a Bilstein DampTronic system, which is the marketing name for a suspension that employs a lot of vehicle sensors to actively adjust shock absorber damping for what Nissan considers an ideal balance of ride and handling performance. Bilstein's DampTronic makes its changes based on the car's speed, lateral acceleration, torque, engine speed, and braking.

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