Do you need the Flywheel

[NewyorkKopter]

Hey, I was wondering whats the purpose of a flywheel. Can you just like get rid of it because wouldn't that give you better engine response, and quicker revs? Like the McLaren F1, it doesn't have a flywheel

[Mustangman25]

The flywheel helps to smooth the roughness that is a given in the four stroke cycle...it provides mass to help the cylinders get through the strokes that they aren't making power on. You need one.

[CBFryman]

you have to have some sort of rotating mass or at least have one piston always onthe power stroke to keep and engine running, otherwise the engine wont be able to keep itsself running. and McClarins do have a flywheel

[NewyorkKopter]

ooo . i read some where online that the McLaren F1 is flywheeless, thus giving it instant F1 car like response

[sierrap615]

the flywheel is also used to connect the engine to the transmission via the clutch or TC, and it holds the ring gear for the starter

[curtis73]

I'm sure that some could get by without the flywheel, but some cannot.

Many engines are externally balanced by putting weights on the damper and flexplate/flywheel. Removing them would cause rapid wear and destruction.

Auto-transmission-equipped cars come with a flexplate that only weighs a couple pounds, but compared to the weight of the rest of the rotating assembly, weight reduction at the flywheel doesn't do as much as you would hope. It does help, but anyone who's carried a crankshaft, a box of pistons and rods, and a harmonic damper knows that a those couple pounds are worth it compared to the slight weight reduction.

Some marine engines are equipped with a very light duty flexplate that is only there to hold the ring gear for the starter. They look like a four-spoke flexplate with big triangular holes.

So, what CBFryman is saying is true to a point, but with 100 lbs of rotating mass already moving in the engine, the few pounds added by flexplates and (to a greater extent) flywheels is neglegible. That component (as some have pointed out) is almost always a key component in attaching the crank to the transmission and starter. So, on an engine that is internally balanced you could run one without it if you could find some way of starting it. Then, once its running, you couldn't have any traditional means of getting the power to the transmission.

To answer your question directly, the flywheel is designed to store energy. In the case of a manual-transmission car, the energy is not being stored for the sake of the engine, its being stored for the sake of driver comfort. If you had a 500-lb flywheel, you wouldn't ever need the accelerator pedal to start the car moving. At idle there would be enough energy stored in the flywheel that you could just pop the clutch out and the car would lurch forward. Of course it would be very slow to accelerate and be very limited in how much speed you can achieve. Normally cars are equipped with a flywheel on the order of 20-40 lbs. That stores enough energy that getting the car moving is relatively easy for the driver but not so much that you notice it in daily driving. Lightweight aluminum billet flywheels are available or can be made for most cars and the purpose is faster response and control of power to the wheels. The trade off is less forgiving street manners. More engine power must be applied to get the car moving without stalling and in the hands of most over-the-counter drivers, its tough to drive and short clutch life and stalling would be the consequence. The flywheel's other main purpose is as the friction surface for the clutch. The clutch itself is pressed against the flywheel to transfer the motion to the transmission.

In the case of the automatic transmission, its equipped with a flexplate and a Torque Converter. Since there is no clutch to worry about, the energy is stored in a fluid coupling in the torque converter. Some of it is converted to heat, just like with the clutch.

[NewyorkKopter]

check it out

its saying the McLaren SLR doesnt have a flywheel
http://www.automotiveforums.com/t272..._mclaren_.html

and over here its saying the Carrera GT doesnt have a flywheel
http://www.supercars.net/PitLane?vie...ID=1&tID=53716

and over here for the McLaren, its not the same site but same idea
http://www.robbreport.com/Articles/W...hese-Years.asp

and ove here for another carrera gt article
http://www.fast-autos.com/fan/carreragtprodn.html

[2turboimports]

oooh, the torque converter is a flywheel for an automatic, (one way to think about it). Auto transmissions don't have flywheels.

[Steel]

auto transmissions dont have aheavy flywheel per se, but dont forget, 12 quarts of ATF isnt light!

[curtis73]

Yeah, and TCs weigh plenty by themselves.

[NewyorkKopter]

o yea tru

[asemstr]

The flexplate takes the place of a flywheel in automatic equipped vehicles. In some race cars a high-mass flexplate is used for increased inertia, RPM stability, and performance! The flywheel by definition is basicly a mass that stores energy through inertia. In a automotive application it smooths the spikes and lapses related to the power pulses of the internal combustion engine, and it functions as mechanical link between the crankshaft and the transmission's input components. But I've already heard of alternative designs useing a starter/generator rotor in the place of a flywheel, and Its just a matter of time before they come come up with engines that have enough power pulse overlap to provide consistant power flow without additional rotateing mass to obsorbe the variation.

[Steel]

Originally Posted by asemstr

and Its just a matter of time before they come come up with engines that have enough power pulse overlap to provide consistant power flow without additional rotateing mass to obsorbe the variation.

how's that supposed to be? you need many cylinders to achive undetectable power pulse lapses.. unless there's technology i dont know aobut yet

[curtis73]

For the most part gasoline engines only apply force during the first 30 degrees of rotation at most. The explosion sorta throws the piston and the expanding gasses continue to add some force, but then the exhaust valve is open by about 160 degrees.

Diesels continue to inject fuel for several degrees of crank rotation, so they are more closely suited to these even pulses that we're talking about.

[asemstr]

Then there's the rotory engines in which all 4 stages of the 4-stroke cycle occur simaltaneously without the vibrations that haunt the reciprocateing assemblies of most shortblock units!