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Originally Posted by Poverty although auto motor and sport said it beat the GTR around the 'ring. Such a massive leap in laptime could be down to the use of the QTV. But then again the R8 always was a better handler than the GTR, it just lacked the grunt. |
Despite being loathe to quote myself, in the light of your post I have to do just that.
QTV is designed to address a problem. It's an inherent problem faced by just about all mechanically conventional AWD saloons. It really would be redundant in the R8.
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Originally Posted by martinbo you must be referring to QTV or Quattro Torque Vectoring, which the R8 doesn't have. In fact its AWD system is quite and obviously different as a result of the mid-engined application. The R8 makes use of a viscous clutch centre differential that can apportion only up to 35% of the torque to the front axle but the current bias if I recall correctly is 10/90 in favour of the rear axle. It also has an electronic rear differential lock or limited slip differential to limit the amount of slip at a given wheel. The reason that an R8 earns such accolades in the handling department has much more to do with its mid-engined supercar layout and not the level of technology thrown at the AWD system.
This is not torque vectoring. Torque vectoring involves the method of directing more torque to a rear-wheel with the best grip in the onset of understeer so traditionally associated with AWD vehicles. This is done via a electro-mechanical clutch and gear pack located in the rear axle differential.
Torque Vectoring is a holistic application - not just focussed on the mechanicals at a given axle. It relies on steering angle sensors, yaw and grip level measurement to determine the dynamic attitude of a vehicle vs. the driver's intended direction. When it senses understeer through all of these systems, QTV then applies more torque to the desired rear wheel in order to turn the nose of the car into the corner. |
QTV's purpose is to address the inherent understeer characteristics exhibited by AWD cars with a front mounted engine. The dynamics that apply to cars with such a layout are quite different to those that arise as a result of a mid-engined layout with 90% of the drive going through the rear axle.
I would be astounded if Audi fitted QTV on the rear axle of the R8 over and above the more than adequate limited-slip differential in the current V8.