FLYWHEEL
11-03-2006, 09:21 PM
#1
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FLYWHEEL
can someone explain what this is? yeah im a noob, but we all gotta start somewhere right? so.. what can a better "flywheel" do for my car? 
lemme know! thanks is advanced!
lemme know! thanks is advanced!
11-03-2006, 10:04 PM
#2
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Scikotics
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A flywheels is the part of the engine/transmission coupling point that the clutch rests against. When you release the clutch pedal, the clutch disc comes into contact with it. The friction between the two allows the engine to turn the transmission. It also is surrouned by teeth that the starter engages to start the engine.
The flywheel is also a means for storing kinetic engery. Due to the properties of inertia, a heaviear flywheel will help to keep the engine at whatever constant speed it is currently spinning. So a heavy flywheel makes for a better launch, since the engine does not slow down as quickly. However it also makes your engine speed rise and lower in a slower fashion due to inertia. A lighter flywheel will make your car rev quicker and drop rpm quicker, but is not as good for launching because of this fact.
Contrary to the way it tricks an inertial dyno (like a dynojet) or what some companies say, a lighter flywheel "adds" or "releases" zero power. All it does is allow the engine to spin up or down quicker.
So, buying a lighter one comes down to the decision of whether you want the engine to hold its momentum more effectively on launch, or if you want it to rev and slow down faster, which is good for rev matching on a track.
I am, however, assuming you have a manual. The flywheel is replaced with a torque convertor on an auto.
The flywheel is also a means for storing kinetic engery. Due to the properties of inertia, a heaviear flywheel will help to keep the engine at whatever constant speed it is currently spinning. So a heavy flywheel makes for a better launch, since the engine does not slow down as quickly. However it also makes your engine speed rise and lower in a slower fashion due to inertia. A lighter flywheel will make your car rev quicker and drop rpm quicker, but is not as good for launching because of this fact.
Contrary to the way it tricks an inertial dyno (like a dynojet) or what some companies say, a lighter flywheel "adds" or "releases" zero power. All it does is allow the engine to spin up or down quicker.
So, buying a lighter one comes down to the decision of whether you want the engine to hold its momentum more effectively on launch, or if you want it to rev and slow down faster, which is good for rev matching on a track.
I am, however, assuming you have a manual. The flywheel is replaced with a torque convertor on an auto.
11-04-2006, 04:04 AM
#4
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engif...
a little more explaination on the power due to a lighter flywheel please? I always thought less rotational mass = more free'd up power... lightweight crank pulley, light flywheel, etc.
I'd like to know the physics
a little more explaination on the power due to a lighter flywheel please? I always thought less rotational mass = more free'd up power... lightweight crank pulley, light flywheel, etc.
I'd like to know the physics
11-04-2006, 07:27 AM
#5
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Reducing rotational mass is the same thing as reducing non rotating mass; it's just that rotational mass has more of an impact.
We all know what power is, right? The ability to exert the product of force and distance over a length of time, or, the amount of work that can be done in a certain amount of time. Power = Force * Distance / Time = Work / time.
Remember the units for torque? Lbs-ft/sec. By reducing flywheel mass, or any mass for that matter, you decrease the amount of work that needs to be done so in essence, you can do more work in the same time. That's why lightening your car makes you faster; there's less work that the engine needs to do. Does this "free up" power? No.
This part most directly answers your question:
Power comes from the combustion of air and gasoline. A flywheel doesn't change the amount of air or gasoline goes into the engine and nor does it change any charateristics about the way the engine breathes.
Inertial dynos only measure acceleration. Since the flywheel or pulley or whatever increases acceleration, the dyno reads that as more power. However, since the flyhweel doesn't touch a thing with the breathing characteristics of the car, there couldn't possibly be any power added or freed up. Freeing up power is removing restrictions and inefficiencies.
Basically, the flywheel frees up some momentum that the engine doesn't need to overcome anymore.
Sorry, engifineer is a lot more concise and detailed and knowledgeable than I am...
We all know what power is, right? The ability to exert the product of force and distance over a length of time, or, the amount of work that can be done in a certain amount of time. Power = Force * Distance / Time = Work / time.
Remember the units for torque? Lbs-ft/sec. By reducing flywheel mass, or any mass for that matter, you decrease the amount of work that needs to be done so in essence, you can do more work in the same time. That's why lightening your car makes you faster; there's less work that the engine needs to do. Does this "free up" power? No.
This part most directly answers your question:
Power comes from the combustion of air and gasoline. A flywheel doesn't change the amount of air or gasoline goes into the engine and nor does it change any charateristics about the way the engine breathes.
Inertial dynos only measure acceleration. Since the flywheel or pulley or whatever increases acceleration, the dyno reads that as more power. However, since the flyhweel doesn't touch a thing with the breathing characteristics of the car, there couldn't possibly be any power added or freed up. Freeing up power is removing restrictions and inefficiencies.
Basically, the flywheel frees up some momentum that the engine doesn't need to overcome anymore.
Sorry, engifineer is a lot more concise and detailed and knowledgeable than I am...
11-04-2006, 05:18 PM
#6
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No, that is pretty good info
At a given rpm you are creating the same amount of power regardless of flywheel weight. At a static speed (which is how a load bearing dyno obtains measurements, it does not run off of acceleration like an inertial dyno) the flywheel weight plays no role in power. As a matter of fact, a lighter one makes it EASIER to slow down the engine. A lighter flywheel does make it easier to spin up the engine, so it revs faster, but you are still applying the same amount of power to the wheels, which is why a good, load bearing dyno will show no increase unless you do some type of a sweep test to fool it. True power measurement comes from static testing. Rotational mass plays the same role at any static speed, be it zero or 5000 rpm.
Now, if you can remove engine friction, parasitic drag (like the air conditioning) or other frictional losses that dissipate power in the form of work or heat, you do free up power. But a rotational mass STORES kinetic energy. So the energy used to spin it up is effectively stored and is still within the system, helping to keep the engine at a constant speed (like at launch). A parasitic drag, like an air conditioner, is taking away from the power transmission by using some of the work for a different purpose. That is why a parasitic drag hurts power output, while a heavier rotational mass does not.
If you want a better understanding other than what is posted here, check out this article:
http://www.germanmotorcars.com/Dyno_...0inertia_1.htm
Dezod posted it in here somewhere as well. The explanation they give of how dynos work should answer most peoples questions about whether or not a lighter flywheel or pulley adds or frees up power. As usual, understanding how the measurements are taken takes a lot of the mis-information out of the way. Although you may feel a little worse about some mods after reading it
But believe it or not, that is a good thing. Typically the more conservative and skeptical answer is the correct one when it comes to power and mods.
At a given rpm you are creating the same amount of power regardless of flywheel weight. At a static speed (which is how a load bearing dyno obtains measurements, it does not run off of acceleration like an inertial dyno) the flywheel weight plays no role in power. As a matter of fact, a lighter one makes it EASIER to slow down the engine. A lighter flywheel does make it easier to spin up the engine, so it revs faster, but you are still applying the same amount of power to the wheels, which is why a good, load bearing dyno will show no increase unless you do some type of a sweep test to fool it. True power measurement comes from static testing. Rotational mass plays the same role at any static speed, be it zero or 5000 rpm.
Now, if you can remove engine friction, parasitic drag (like the air conditioning) or other frictional losses that dissipate power in the form of work or heat, you do free up power. But a rotational mass STORES kinetic energy. So the energy used to spin it up is effectively stored and is still within the system, helping to keep the engine at a constant speed (like at launch). A parasitic drag, like an air conditioner, is taking away from the power transmission by using some of the work for a different purpose. That is why a parasitic drag hurts power output, while a heavier rotational mass does not.
If you want a better understanding other than what is posted here, check out this article:
http://www.germanmotorcars.com/Dyno_...0inertia_1.htm
Dezod posted it in here somewhere as well. The explanation they give of how dynos work should answer most peoples questions about whether or not a lighter flywheel or pulley adds or frees up power. As usual, understanding how the measurements are taken takes a lot of the mis-information out of the way. Although you may feel a little worse about some mods after reading it
But believe it or not, that is a good thing. Typically the more conservative and skeptical answer is the correct one when it comes to power and mods.
11-05-2006, 10:06 PM
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I would imagine a lot, since it is a very labor-intensive process. The part itself isn't that much... its pretty much all labor. I'm sure easily over $700, seeing as how it involves the same labor as a replacing a clutch (which cost <$1000 from what I hear).
If you can do it yourself you save a lot of money. For me, I just adjust to the stock flywheel. I think daily driving with a lightweight flywheel would probably suck.
If you can do it yourself you save a lot of money. For me, I just adjust to the stock flywheel. I think daily driving with a lightweight flywheel would probably suck.
11-05-2006, 11:40 PM
#10
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Originally Posted by paul34
I would imagine a lot, since it is a very labor-intensive process. The part itself isn't that much... its pretty much all labor. I'm sure easily over $700, seeing as how it involves the same labor as a replacing a clutch (which cost <$1000 from what I hear).
If you can do it yourself you save a lot of money. For me, I just adjust to the stock flywheel. I think daily driving with a lightweight flywheel would probably suck.
If you can do it yourself you save a lot of money. For me, I just adjust to the stock flywheel. I think daily driving with a lightweight flywheel would probably suck.
11-06-2006, 12:46 AM
#12
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now i understand that a lightend flywheel doesnt add power; it enables the engine to speed up faster. my question is would installing a lightend flywheel help your quarter mile time any? if you could compare the acceleration improvment to something that does make horse power what would it be?
11-06-2006, 12:51 AM
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Originally Posted by engifineer
I am, however, assuming you have a manual. The flywheel is replaced with a torque convertor on an auto.
11-06-2006, 01:49 AM
#14
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Which is exactly what I was saying really. An auto doesnt have a flywheel, rather it has a torque convertor/flexplate assembly.
As far as cost to install, I would just do it yourself if you have the tools and experience. It really isnt a hard job, just a little time consuming, which is why it can get expensive. I believe on this car (just by looking) it isnt too hard to seperate the tranny and engine in the car (some cars nearly requires dropping the motor and transaxle out as one unit.). For example, on my Saturn you are supposed to pull both, but with a little patience you can seperate them just enough to swap the clutch out, at least that is how I did it. The tC looks pretty open in that area so I dont think it would be a terrible job to tackle compared to many other cars. But, as mentioned, I would replace the clutch as well. Find the flywheel you want (I hear the fidanza is great) and get the clutch you want at the same time. Dont go overly aggressive on the clutch unless you primarilly race the car. A super aggressive clutch can be a pain on the street.
As far as cost to install, I would just do it yourself if you have the tools and experience. It really isnt a hard job, just a little time consuming, which is why it can get expensive. I believe on this car (just by looking) it isnt too hard to seperate the tranny and engine in the car (some cars nearly requires dropping the motor and transaxle out as one unit.). For example, on my Saturn you are supposed to pull both, but with a little patience you can seperate them just enough to swap the clutch out, at least that is how I did it. The tC looks pretty open in that area so I dont think it would be a terrible job to tackle compared to many other cars. But, as mentioned, I would replace the clutch as well. Find the flywheel you want (I hear the fidanza is great) and get the clutch you want at the same time. Dont go overly aggressive on the clutch unless you primarilly race the car. A super aggressive clutch can be a pain on the street.
11-07-2006, 05:54 PM
#15
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i can attest to the super aggressive clutch being a pain on the street. i used to own an 89 maxima that had some work done to it, which included a ACT 6 puck unsprung racing clutch. of course this was before they offered the sprung version of the same clutch. let me just say this, if you werent ready for the clutch to be engaged when you started letting off the pedal you were either going to stall the car or run someone over with it. there were many times during the period where i was getting accustomed to it that i almost lost control of the car starting out from a stop. however, if you can get used to it and dont mind the aggressiveness of it then i highly recommend it. i could easily chirp tire in all 5 gears with it. plus i did a killer burnout as i was leaving the dealership that installed it for me.
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