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Re: it's all wrong...(long) |
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| Posted by |
nemo on May 25, 2000 at 3:08 AM |
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This message has been viewed 199 times. |
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| In Reply To |
One piece Alum driveshaft HP gain has been calculated!!!! posted by BPC23 on May 24, 2000 at 08:41 PM |
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| Message |
rotating inertia:(this is from a race car engineering book). Most car enthusiasts know that reducing weight will increase acceleration with the same horsepower. What is less well-known is that if the weight, and its distribution, of the driveline components are reduced, the improvment in acceleration can be much greater than that which would be realized for just reducing the car weight. The weight and its distribution of a driveline component about its center of rotation is called rotating inertia. This resistance to rotational acceleration is called rotating inertia, because its effect is seen when the parts are accelerated rotationally.The easiest way to picture this condition is to compare how hard it would be to rotate two object that weigh the same(cannonbal vs. dumbbell). If your car had a flywheel that had most of its weight concentrated around the rim, it would have greater resistance to revving quickly than a flywheel that had its weight concentrated around its center. Obviously, a lighter flywheel would be even better because it would not only weigh less, but it would also have less rotating inertia. Many enthusiasts are familiar with this concept, so it is interesting to look at an example to see just how much effect rotating inertia has on a car's ability to accelerate. Chassis rotating inertia: All the rotating parts in the chassis have inertia which resists angular acceleration. These parts include the tires, the wheels, the brake rotors, the hubs and the ring gear and the differential. Driveline rotating inertia: The rotating parts of the driveline include the crankshaft, the flywheel, the clutch, the transmission gears and the driveshaft. Since these parts operate at much higher rpm, the effect their rotating inertia has on acceleration is much greater. baseline -15lbs. -15lbs. -15lbs. car weigh total rotating rotat. weight weight weight @axle @engine speed speed
weight; 3000lbs 2985 2985 2985 accele- rtion force; .444g's .446g's .450g's .474g's speed@ start of strait- away; 64mph 64mph 64mph 64mph speed@ and of strait- away; 112.74 112.95 113.34 115.74 change; 0mph .21mph .60mph 3.00mph equivalent horsepower; 428 430.55 434.83 460.51 hp change; 0 2.55 6.83 32.51 improvement factor; 0 1 3 15 The important thing that this Chart shows is that it is 15 times as important to reduce the weight of components that rotate at engine speed than it is to reduce the weight of other components of the car. Components that rotate at axle speed are 3 times as effective as non-rotating components.
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20:49:14 05/24/00
