flywheel

what does a flywheel do?

1. It stores and releases energy. It has rotational mass which allows you to release the clutch more easily without stalling it. Also, it helps prevent you from overrevving the engine as easily if you miss a shift.
2. It provides balance for the engine. Without it the crankshaft would quickly snap in two due to rotational vibrations. It also provides lateral vibration balancing, so the engine is less likely to shake.
3. It is a handy place for a clutch, (or torque converter) and starter motor ring gear to attach.

The flywheel has basicly only one function, to smoothen out the power pulses created by the engine.

The torsional vibration is an issue for the torsion damper. There is no problem to run an engine without a flywheel.

What the previous two guys said was true. in addition to that, the flywheel is used primarily to store rotational energy such that when the engine isnt on the power stroke of any piston, it can still maintain rotation to compress the next piston in line. if the next piston doesnt make it all the way to the top (where it will be fired), then the engine will stall.

You can run most engines with no flywheel, with the exception of some motorcycle engines and other very lightweight, small capacity engines. if its a large, V12, the power stroke is bound to be on at least on of the pistons/cylenders, so they can get away with having a minute flywheel. one must also bear in mind that the crankshaft acts as a flywheel too, and that the valvetrain (unless its the new coates spherical rotary valves - check it out! - revolutionary) takes its share of rotational force as well.

It may also depend on where the weight is located on the flywheel because if most of the weight is located on the outer diameter it will have more force but releases it energy fast than if most of the mass is located near the center where force would be lower but release would be longer.... but i could be mental.

close. the weights location on the flywheel does affect its energy capacity, but it doesnt affect how long it takes to release it. generally, the more energy it can store, the longer it can let it go. essentially, the energy is taken at whatever rate the surronding system demands of it, but the supply will last longer with a heavier flywheel.

if it balances it out and stuff then wouldnt it be bad for the engine by a aftermarket one that weighs less wouldnt that create an unbalance and make the engine shake more?

usually, the balancing / reducing of vibration is only detectable at idle, so if you dont mind either
a)having a rougher idle, placing more strain on the engines mounts, valve train etc
b)having a higher idle, reducing the engines lifespan cause its working harder just to stay in motion.

both of these effects are pretty miniscule becuase most road cars have flywheels that are very heavey to make their engines seem silky smooth. most road going engines wouldnt be hurt at all by replacing the flywheel with a lighter one

usually, the balancing / reducing of vibration is only detectable at idle, so if you dont mind either
a)having a rougher idle, placing more strain on the engines mounts, valve train etc
b)having a higher idle, reducing the engines lifespan cause its working harder just to stay in motion.

both of these effects are pretty miniscule becuase most road cars have flywheels that are very heavey to make their engines seem silky smooth. most road going engines wouldnt be hurt at all by replacing the flywheel with a lighter one

well im thinking about geting one a sentra spec-v and the flywheel is around 20 stock and i want to get ether a 11 or 8 pound one what you think that will do to it pros and cons?

usually, the balancing / reducing of vibration is only detectable at idle, so if you dont mind either
a)having a rougher idle, placing more strain on the engines mounts, valve train etc
b)having a higher idle, reducing the engines lifespan cause its working harder just to stay in motion.

both of these effects are pretty miniscule becuase most road cars have flywheels that are very heavey to make their engines seem silky smooth. most road going engines wouldnt be hurt at all by replacing the flywheel with a lighter one
The fly wheel has no balancing effect. That the engine runs a little more rough at idle with no flywheel depends on that the pulses from the engine aren't that smooth. It will not cause more vibrations but will be a little harder on the clutch and gearbox but not that much.

The fly wheel has no balancing effect. .

Depends on the motor, externally balanced engines do require special (non-neutral) flywheels/flexplates

saabjohan, you are right when you say that the flywheel doesnt balance any lateral vibration, but it does reduce torsional vibrations greatly. and as quaddriver pointed out, some flywheels DO form part of the lateral balancing system.

for once, everyone says different things and everyone is still right (in some way).

The fly wheel has no balancing effect. That the engine runs a little more rough at idle with no flywheel depends on that the pulses from the engine aren't that smooth. It will not cause more vibrations but will be a little harder on the clutch and gearbox but not that much.

ya im planing on get a really nice clutch kit anyways so i doubt it will do anything the the new clutch so ill just get it if it seems like its wrecking anything ill just put the stock back