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Leawood911 said:
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Grant said:
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Leawood911 said:Someone on this forum had an interesting formula that compared saving unsprung vs. sprung weight. Each pound of unsprung weight saved was equal to 5 pounds of sprung weight. The net effect of PCCB turned out to be about a 20 hp advantage - nearly equal to X-51 in terms of power to weight and much cheaper


Unsprung weight vs. Sprung weight does not matter with regard to acceleration (just handling and ride quality). The benefit of PCCB with regard to acceleration comes from the fact that it's rotating mass. It's a similar effect to using a lighter flywheel on the engine (which is sprung mass).



Less unsprung weight certainly does impact acceleration, sorry (In fact you make the same point in your statement although you are correct that a flywheel is not un-sprung weight)

The more mass an object has, the more energy it takes to accelerate it. To accelerate a rolling object such as a wheel, you must both accelerate its mass plus overcome its rotational inertia. As for braking, you must overcome its rotational inertia plus decelerate its mass. By reducing the weight of the vehicle's rotational mass, lightweight wheels/brakes provide more responsive acceleration and braking.
The effect of rotating mass can be calculated using Moment of Inertia (MOI). MoI is related to not only the mass of the rotating object, but the distribution of that mass around the rotational center. The further from the center, the higher the MoI. The higher the MoI, the more torque required to accelerate the object. The higher the acceleration, the higher the torque required.

Because of this, the weight of rotating mass such as wheels, tires and rotors on a car have a bigger effect on acceleration than static weight such as on the chassis on a car.

The use of PCCB reduces rotational mass. This means that less energy will be required to accelerate the wheel. Given that each pound of rotational mass lost provides an equivalent performance gain as a 10 pound reduction in vehicle weight, the benefits of carbon ceramic brakes on vehicle performance cannot be overlooked.





You appear to be overlooking the fact that not all unsprung masses are rotating masses.

A hub carrier is an unsprung mass, but it is not a rotating mass, so its effect on accelaration is pound-for-pound weight exactly the same as a sprung mass.