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Old 04-26-2006, 09:43 PM   #1
ehhh
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Fly wheel

Ok i am curious on how a fly wheel works like what it does in a car and if like weight and anything really matters. I couldn't find it on howstuffworks.com and i searched it on google but i didn't really get what it was sayin since it was givin me an equation E=Iomegapower of 2 sht and stuff and yeah it lost me. so if anyone can give me a general idea first and then give me a lil more detail idea after i grasp the general idea or just a website that explains it in lamens
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Old 04-26-2006, 10:32 PM   #2
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Pretty simple concept really. The flywheel is a rotating mass. Because it's a rotating mass it builds a store of latent energy. Anything connected to it's shaft that causes a perturbation will tend to have it's influence dampened as the flywheel transfers latent energy to kinetic energy. As Newton pointed out, an object in motion tends to stay in motion. The greater the mass of the object the less inclined it is to change direction. Yadda, yadda, yadda.

So in a four stroke engine you have four uneven phases per cycle. Even within each stroke the forces are uneven. Now it's pretty obvious the power stroke is going to want to keep the flywheel and car going in the desired direction, but the same can't be said for the other three, especially the compression stroke. It's also very important for the pistons to maintain certain velocities and accelerations for the induction and exhaust cycles to work. The flywheel imparts it's stored energy in the form of force to keep the motion of the engine stabile.

By now you have probably google read that a flywheel is analogous to battery, but a battery doesn't smooth out harmonics and wave forms in electronics, nor does it figure in timing cicuits, but a capacitor does. Like a capacitor, once it's charged it does not draw any power, but while it's charging it draws heaps initially, gradually tailing off. So without generally knowing why, boyracers lighten their flywheels for supadupa launches at the traffic lights and live with the consequent engine desire to stall.

The part of the flywheel that stores the energy is the rim, not the plate (which usually doubles as the clutch plate mating surface) that connects the rim to the crankshaft. So when you look at those confusing maths formulae, you can make sense of why they talk about the radius,etc.
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Old 04-27-2006, 04:48 AM   #3
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Quote:
Originally Posted by Wally
Pretty simple concept really. The flywheel is a rotating mass. Because it's a rotating mass it builds a store of latent energy. Anything connected to it's shaft that causes a perturbation will tend to have it's influence dampened as the flywheel transfers latent energy to kinetic energy. As Newton pointed out, an object in motion tends to stay in motion. The greater the mass of the object the less inclined it is to change direction. Yadda, yadda, yadda.

So in a four stroke engine you have four uneven phases per cycle. Even within each stroke the forces are uneven. Now it's pretty obvious the power stroke is going to want to keep the flywheel and car going in the desired direction, but the same can't be said for the other three, especially the compression stroke. It's also very important for the pistons to maintain certain velocities and accelerations for the induction and exhaust cycles to work. The flywheel imparts it's stored energy in the form of force to keep the motion of the engine stabile.

By now you have probably google read that a flywheel is analogous to battery, but a battery doesn't smooth out harmonics and wave forms in electronics, nor does it figure in timing cicuits, but a capacitor does. Like a capacitor, once it's charged it does not draw any power, but while it's charging it draws heaps initially, gradually tailing off. So without generally knowing why, boyracers lighten their flywheels for supadupa launches at the traffic lights and live with the consequent engine desire to stall.

The part of the flywheel that stores the energy is the rim, not the plate (which usually doubles as the clutch plate mating surface) that connects the rim to the crankshaft. So when you look at those confusing maths formulae, you can make sense of why they talk about the radius,etc.
I must say, well said.
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Old 04-27-2006, 12:04 PM   #4
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Quote:
Originally Posted by Wally
Pretty simple concept really. The flywheel is a rotating mass. Because it's a rotating mass it builds a store of latent energy. Anything connected to it's shaft that causes a perturbation will tend to have it's influence dampened as the flywheel transfers latent energy to kinetic energy. As Newton pointed out, an object in motion tends to stay in motion. The greater the mass of the object the less inclined it is to change direction. Yadda, yadda, yadda.

So in a four stroke engine you have four uneven phases per cycle. Even within each stroke the forces are uneven. Now it's pretty obvious the power stroke is going to want to keep the flywheel and car going in the desired direction, but the same can't be said for the other three, especially the compression stroke. It's also very important for the pistons to maintain certain velocities and accelerations for the induction and exhaust cycles to work. The flywheel imparts it's stored energy in the form of force to keep the motion of the engine stabile.

By now you have probably google read that a flywheel is analogous to battery, but a battery doesn't smooth out harmonics and wave forms in electronics, nor does it figure in timing cicuits, but a capacitor does. Like a capacitor, once it's charged it does not draw any power, but while it's charging it draws heaps initially, gradually tailing off. So without generally knowing why, boyracers lighten their flywheels for supadupa launches at the traffic lights and live with the consequent engine desire to stall.

The part of the flywheel that stores the energy is the rim, not the plate (which usually doubles as the clutch plate mating surface) that connects the rim to the crankshaft. So when you look at those confusing maths formulae, you can make sense of why they talk about the radius,etc.

flywheels can't really do that much for harmonics (except for ext. balanced motors) b/c if they did, automatic cars would shake like crazy....
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Old 04-27-2006, 12:34 PM   #5
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Quote:
Originally Posted by dodger65
flywheels can't really do that much for harmonics (except for ext. balanced motors) b/c if they did, automatic cars would shake like crazy....

Automatic cars have heavy, fluid filled torque converters bolted to the flexplate that tend to do a bit of that job. That fluid drive that's running all the time the engine is smooths out the harmonics...
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Old 04-27-2006, 10:56 PM   #6
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Quote:
Originally Posted by dodger65
flywheels can't really do that much for harmonics (except for ext. balanced motors) b/c if they did, automatic cars would shake like crazy....

Well a corollary to you own statement would be that a manual car without a flywheel would not shake like crazy, but in truth, apart from the thing not going anywhere, it will. You may be confusing the role of an harmonic balancer aka a damper.
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Old 04-27-2006, 11:04 PM   #7
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Not to hijack this thread but I have a question about clutches, what do they mean when they say like "8 puck" etc..?
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Old 04-27-2006, 11:21 PM   #8
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http://www.funrunr.com/clutches.htm
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Old 04-27-2006, 11:35 PM   #9
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Quote:
Originally Posted by Wally
Well a corollary to you own statement would be that a manual car without a flywheel would not shake like crazy, but in truth, apart from the thing not going anywhere, it will. You may be confusing the role of an harmonic balancer aka a damper.

well, a manual car w/o a flywheel wouldn't even start, wally.... (no ring gear)

i fired up a friend's car while i had the tranny out, and it ran fairly smooth (kinda hard to tell, buncha cam in it...) it revved great, though...

edit: touche', chris... forgot about the converter being heavy....
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Old 04-28-2006, 12:23 AM   #10
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The absence of ring gear could be a problem starting I admit.
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Old 04-28-2006, 01:45 AM   #11
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So without generally knowing why, boyracers lighten their flywheels for supadupa launches at the traffic lights and live with the consequent engine desire to stall.

T

I have a 9 lbs flywheel, and never stalls.
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Old 04-28-2006, 02:17 PM   #12
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Well good for you, but ~4kg on what motor? And what exactly are you trying to make a point of..... that flywheels are not required and engine designers have been wasting the production plant's money?
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Old 04-28-2006, 09:47 PM   #13
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Quote:
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Well good for you, but ~4kg on what motor? And what exactly are you trying to make a point of..... that flywheels are not required and engine designers have been wasting the production plant's money?
He means he likes cheese on his hamburgers.
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