unsprung weight, how is it to calculate hp to it. 16lbs added what is the loss.
10-04-2005, 06:19 PM
#2
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No ... you are thinking of centrifical mass...
Reducing the flywheel weight of the drive train will give you an apparent power increase under acceleration.
The advantage of unsprung weight is improved handling as the suspension is better able to react to the road irregularities and keep the tyre in contact with the road more.
Stephen
The advantage of unsprung weight is improved handling as the suspension is better able to react to the road irregularities and keep the tyre in contact with the road more.
Stephen
10-04-2005, 06:24 PM
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How would adding weight to your car reduce power?
If you stuffed 10 people in your car, it would still have the same power. You wouldn't accelerate as fast, but you'd have the same power.
Your posts never cease to amaze me.
Your posts never cease to amaze me.
10-04-2005, 06:30 PM
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It will actually...
The reason being that those wheels are a part of the rotating mass of the drivetrain. You need to accelerate those wheels (spinning them up in a circle) just as you must accelerate the drive shafts, transmission, flywheel, engine, etc.
But the wheels are accelerated much less than the flywheel and engine are. So the difference is small even though the mass is further out from the centre point of rotation than the mass of the transmission and drive shafts is.
An additional 16 lbs in new wheels will also increase the unsprung weight as those wheels need to be accelerated up and down as the suspension hits bumps. Most will tell you that you cannot feel the difference but I can. With more mass at the ends of the springs, it is more mass for the dampers to control. So adding mass feels like softer dampers and taking mass away is like using stiffer dampers.
Stephen
But the wheels are accelerated much less than the flywheel and engine are. So the difference is small even though the mass is further out from the centre point of rotation than the mass of the transmission and drive shafts is.
An additional 16 lbs in new wheels will also increase the unsprung weight as those wheels need to be accelerated up and down as the suspension hits bumps. Most will tell you that you cannot feel the difference but I can. With more mass at the ends of the springs, it is more mass for the dampers to control. So adding mass feels like softer dampers and taking mass away is like using stiffer dampers.
Stephen
10-04-2005, 06:32 PM
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sorry i did not meant like if i have 300 hp it will go to 290 hp, what i meant to ask was unprung
weight will not make me loose power. answer" unsprung weight would be the light weight flywheel" better acceleration. but the adding weight in the rims, is it or not rotational mass, at that matter will act just like the flywheel. slower acceleration, a feeling of less butt power.
sorry if i was not clear.
sorry if i was not clear.
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10-04-2005, 06:45 PM
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Its not that you lose hp with heavier wheels...
Its because for heavier wheels, the moment of inertia is higher; therefore, you need more effort to get them spnning (try turning a glass plate vs turning a styrofoam plate). So it's not that you lose power, more power is just used to spin the heavier wheels instead of being put onto the ground. You might see a slightly higher wheel hp on dyno when you use lighter wheels, but the crank hp wouldnt change just because you have lighter wheels. The higher momement of inertia from heavier wheel also requires more effort from the brake to slow them down (object in motion tend to stay in motion). That's why using ligher wheels can help reduce brake fade to some extent.
10-04-2005, 06:50 PM
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On the topic of braking...
Just as a heavy flywheel makes for a more stable engine, so too do heavier wheels make for a more stable wheel speed. That means it is less easy to lock the wheels and less easy to unlock them again.
And for us ABS folk, if it is very different to what the ABS system was originally designed for, it can be quite confusing to that ABS system.
Stephen
And for us ABS folk, if it is very different to what the ABS system was originally designed for, it can be quite confusing to that ABS system.
Stephen
