Single Mass Flywheel
#1
Single Mass Flywheel
Hi,
I'm thinking of fitting my S2 with a "performance" flywheel while the tranny is out for the clutch job.
I'd be very happy to have some feedback from S2 owners who have already upgraded the flywheel.
Also what are the effects of fitting a lighter flywheel apart from making the engine rev faster ?
Thanks in advance for any opinion/experience.
I'm thinking of fitting my S2 with a "performance" flywheel while the tranny is out for the clutch job.
I'd be very happy to have some feedback from S2 owners who have already upgraded the flywheel.
Also what are the effects of fitting a lighter flywheel apart from making the engine rev faster ?
Thanks in advance for any opinion/experience.
Last edited by Thom; 01-04-2004 at 05:11 PM.
#2
Hi Thom,
I had this discussion with a mate of mine who's a engineer.
basically a loosened flywheel, whilst, has less mass will spin faster giving you better acceleration, it will also induce more vibration. this could have an effect on the engine as a whole and any weak parts throughout.
as for performance gain ? is it worth it.
Unless your fast tracking it or racing, then I'd say leave well alone.
S2's have got good grunt, get the rev's right up before changing gear.
I had this discussion with a mate of mine who's a engineer.
basically a loosened flywheel, whilst, has less mass will spin faster giving you better acceleration, it will also induce more vibration. this could have an effect on the engine as a whole and any weak parts throughout.
as for performance gain ? is it worth it.
Unless your fast tracking it or racing, then I'd say leave well alone.
S2's have got good grunt, get the rev's right up before changing gear.
#3
I think somebody better check his engineering degree. A lighter rotating mass will not have any more/less vibration than a heavier one, assuming that they were both balanced to the same spec.
I have never expierenced a stock and lightened flywheel on a 944S2, but I have on other cars. The difference in responce from the engine was fenominal. If you are a capeable manual transmission driver then I would do it in a heartbeat (or less). If you are not then leave it alone.
A lighter flywheel WILL make starting off in first gear more difficult.
It will make your in gear acceleration awesome.
It will reduce your ability to spin the tires when shifting gears.
For those of you that don't know, a Flywheel is an Energy Storage Device. It does much more than simply provide a mating surface for your clutch disk.
The heavier the flywheel, the more energy it will store and the more energy it will take to spin it.
The lighter the flywheel, the less energy it will store and the less energy it will take to spin it.
I have never expierenced a stock and lightened flywheel on a 944S2, but I have on other cars. The difference in responce from the engine was fenominal. If you are a capeable manual transmission driver then I would do it in a heartbeat (or less). If you are not then leave it alone.
A lighter flywheel WILL make starting off in first gear more difficult.
It will make your in gear acceleration awesome.
It will reduce your ability to spin the tires when shifting gears.
For those of you that don't know, a Flywheel is an Energy Storage Device. It does much more than simply provide a mating surface for your clutch disk.
The heavier the flywheel, the more energy it will store and the more energy it will take to spin it.
The lighter the flywheel, the less energy it will store and the less energy it will take to spin it.
#6
Originally posted by W88951
I think somebody better check his engineering degree. A lighter rotating mass will not have any more/less vibration than a heavier one, assuming that they were both balanced to the same spec.
I have never expierenced a stock and lightened flywheel on a 944S2, but I have on other cars. The difference in responce from the engine was fenominal. If you are a capeable manual transmission driver then I would do it in a heartbeat (or less). If you are not then leave it alone.
A lighter flywheel WILL make starting off in first gear more difficult.
It will make your in gear acceleration awesome.
It will reduce your ability to spin the tires when shifting gears.
For those of you that don't know, a Flywheel is an Energy Storage Device. It does much more than simply provide a mating surface for your clutch disk.
The heavier the flywheel, the more energy it will store and the more energy it will take to spin it.
The lighter the flywheel, the less energy it will store and the less energy it will take to spin it.
I think somebody better check his engineering degree. A lighter rotating mass will not have any more/less vibration than a heavier one, assuming that they were both balanced to the same spec.
I have never expierenced a stock and lightened flywheel on a 944S2, but I have on other cars. The difference in responce from the engine was fenominal. If you are a capeable manual transmission driver then I would do it in a heartbeat (or less). If you are not then leave it alone.
A lighter flywheel WILL make starting off in first gear more difficult.
It will make your in gear acceleration awesome.
It will reduce your ability to spin the tires when shifting gears.
For those of you that don't know, a Flywheel is an Energy Storage Device. It does much more than simply provide a mating surface for your clutch disk.
The heavier the flywheel, the more energy it will store and the more energy it will take to spin it.
The lighter the flywheel, the less energy it will store and the less energy it will take to spin it.
I said, it will give you better acceleration, which it does.
by shear fact that its heavier, its also acting as a damper, you lighten it, the engine will suffer from more vibration.
this has been discussed and debated here, so check the archives
#7
adrian, I never questioned the fact that you will have better acceleration.
What is in question was that a lighter flywheel will cause more vibration.
IT WILL NOT.
What will cause vibration is an Unbalanced Engine. If a heavier flywheel reduces the vibration of an unbalanced engine by means of greater mass and if you install a lighter flywheel in the car and now you have rattles, it is not the fault of the Flywheel.
What is in question was that a lighter flywheel will cause more vibration.
IT WILL NOT.
What will cause vibration is an Unbalanced Engine. If a heavier flywheel reduces the vibration of an unbalanced engine by means of greater mass and if you install a lighter flywheel in the car and now you have rattles, it is not the fault of the Flywheel.
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#9
ok, I done done some research, also spoken to a guy who's done this to a few cars.
see also below one the FAQ I found. This makes sense and confirms to somewhat what I have already said.
Fly wheel
The fly wheel is what is connected to the engine. The engine is cranking the fly wheel around. Basically, you can look at it like it is a large metal disk that is connected to the driveshaft. Every time a cylinder fires, it helps spin the fly wheel.
Once a heavy fly wheel is in motion, the momentum (mass * velocity…the heavier the fly wheel, the more momentum) smoothes out the engine/cylinder “pulses”.
read as "smoothes out the engine/cylinder pulses"
It is this momentum and the ability of the fly wheel to maintain a constant speed that allows you to launch a car smoothly. If a fly wheel has little mass, it has a harder time keeping the engine at the same speed and can stall when the gear is engaged.
It is for driving/launch ease that most manufacturers use a somewhat heavy fly wheel. A lighter flywheel does not have as much ability to maintain the engine speed when a load is applied to it. While that makes launching the car a little more difficult, it makes the engine much more “rev” happy! No longer is an engine slowed down in its acceleration/deceleration by the momentum of a heavy fly wheel.
A lighter flywheel makes a huge performance increase!
and as the clutch is also directly related to this topic
Clutch
The clutch engages the engine through use of a pressure plate. The pressure plate pushes the high friction, clutch surface in contact with the fly wheel…until they are “engaged”.
When things are too powerful…
If the “hotty” is too “hot” for you (or too powerful in the case of an engine), you may initially “slip” in your connection. Harmful to the clutch in your car!
When you add a lot of power, or do a lot of high RPM launches, the stock clutch does not have the ability to adhere or clamp to the fly wheel. It is a sure way to go through a clutch quickly.
High performance clutch have higher clamping power. That means that they are less likely to wear out quickly, but most importantly, can handle higher engine power output.
The downside to a high performance clutch is similar to its advantage…no or little slippage. Some slippage reduces the immediate shock to the transmission and also makes for a “smoother” launch
so re-reading that,
a lightened flywheel, give you a rev happy engine, one which is more likly to stall, a stock (or heavy f/wheel) smoothes out the engine pulse.
a smoother running engine has got to be in the long run, a better choice than one that is trying to run flat out.
F1 engines et a rebuild every race, run close to blowing. Stock cars are designed for longevity and overall performance. Track day cars are again a different kettle of fish.
If you want to track your car, lighten the flywheel, stick a race clutch on, and go for broke.
Like most things in the Porsche world nothing is cheap, however s2's, 68's and 51 are really fast cars'. stick with the standard, you'll get a great car, whoich goes like sheet and wont be breaking down every couple of miles.
Dont forget its the boy racers, ricer boys in there cars which AINT sports cars which they are trying to soup up.
we dont need to.
see also below one the FAQ I found. This makes sense and confirms to somewhat what I have already said.
Fly wheel
The fly wheel is what is connected to the engine. The engine is cranking the fly wheel around. Basically, you can look at it like it is a large metal disk that is connected to the driveshaft. Every time a cylinder fires, it helps spin the fly wheel.
Once a heavy fly wheel is in motion, the momentum (mass * velocity…the heavier the fly wheel, the more momentum) smoothes out the engine/cylinder “pulses”.
read as "smoothes out the engine/cylinder pulses"
It is this momentum and the ability of the fly wheel to maintain a constant speed that allows you to launch a car smoothly. If a fly wheel has little mass, it has a harder time keeping the engine at the same speed and can stall when the gear is engaged.
It is for driving/launch ease that most manufacturers use a somewhat heavy fly wheel. A lighter flywheel does not have as much ability to maintain the engine speed when a load is applied to it. While that makes launching the car a little more difficult, it makes the engine much more “rev” happy! No longer is an engine slowed down in its acceleration/deceleration by the momentum of a heavy fly wheel.
A lighter flywheel makes a huge performance increase!
and as the clutch is also directly related to this topic
Clutch
The clutch engages the engine through use of a pressure plate. The pressure plate pushes the high friction, clutch surface in contact with the fly wheel…until they are “engaged”.
When things are too powerful…
If the “hotty” is too “hot” for you (or too powerful in the case of an engine), you may initially “slip” in your connection. Harmful to the clutch in your car!
When you add a lot of power, or do a lot of high RPM launches, the stock clutch does not have the ability to adhere or clamp to the fly wheel. It is a sure way to go through a clutch quickly.
High performance clutch have higher clamping power. That means that they are less likely to wear out quickly, but most importantly, can handle higher engine power output.
The downside to a high performance clutch is similar to its advantage…no or little slippage. Some slippage reduces the immediate shock to the transmission and also makes for a “smoother” launch
so re-reading that,
a lightened flywheel, give you a rev happy engine, one which is more likly to stall, a stock (or heavy f/wheel) smoothes out the engine pulse.
a smoother running engine has got to be in the long run, a better choice than one that is trying to run flat out.
F1 engines et a rebuild every race, run close to blowing. Stock cars are designed for longevity and overall performance. Track day cars are again a different kettle of fish.
If you want to track your car, lighten the flywheel, stick a race clutch on, and go for broke.
Like most things in the Porsche world nothing is cheap, however s2's, 68's and 51 are really fast cars'. stick with the standard, you'll get a great car, whoich goes like sheet and wont be breaking down every couple of miles.
Dont forget its the boy racers, ricer boys in there cars which AINT sports cars which they are trying to soup up.
we dont need to.
#10
adrian,
Do you have ANY practicle expierence with lightened flywheels? Have you ever installed one on your car or any car for that matter?
Also, if you are going to "quote" a published article, please post a link or a source refernce.
Something like this.
"a heavy wheel that stores kinetic energy and smoothes the operation of a reciprocating engine"
Refernce: http://dictionary.reference.com/search?q=Flywheel
Another great link to Non-Automotive use of a flywheel
http://www.upei.ca/~physics/p261/pro.../flywheel1.htm
Now, back to the vibration thing. I found several resources mentioning how a flywheel is used to smoothe the power output from a recipricating engine. However, from my practicle expierence with lightened flywheels for automotive use, I never noticed any increase in vibration from the engine due to a lighter flywheel. This is both with 944's and other cars. And when I mean lighter I mean 5~7lbs lighter.
And rebuilding an F1 engine or Nascar or any other High level motorsport has nothing to do with the Flywheel. Those Flywheels have practially no Mass. Becasue they want all to power to be instantly transfrered from the engine to the drive wheels. If you ever see one stall when launching from the pits it is entirely because their flywheel has no mass.
"a smoother running engine has got to be in the long run, a better choice than one that is trying to run flat out"
Again, you are making assumptions on something that you have no practicle knowledge. If you make a statement like that, please enlighten us as to why it "has got to be". Your statement doesn't even have confidence as fact.
I will admit that I was wrong about one purpose of a flywheel to "Smoothe out an Engine" but I was speaking about flywheels and thier function from my practicle expierence as well as my understanding of their purpose as an engergy storage / transfer device.
"Dont forget its the boy racers, ricer boys in there cars which AINT sports cars which they are trying to soup up.
we dont need to."
I guess that is why the majority of users in this Forum have a list of Improvements to their car listed in their Sig.
Do you have ANY practicle expierence with lightened flywheels? Have you ever installed one on your car or any car for that matter?
Also, if you are going to "quote" a published article, please post a link or a source refernce.
Something like this.
"a heavy wheel that stores kinetic energy and smoothes the operation of a reciprocating engine"
Refernce: http://dictionary.reference.com/search?q=Flywheel
Another great link to Non-Automotive use of a flywheel
http://www.upei.ca/~physics/p261/pro.../flywheel1.htm
Now, back to the vibration thing. I found several resources mentioning how a flywheel is used to smoothe the power output from a recipricating engine. However, from my practicle expierence with lightened flywheels for automotive use, I never noticed any increase in vibration from the engine due to a lighter flywheel. This is both with 944's and other cars. And when I mean lighter I mean 5~7lbs lighter.
And rebuilding an F1 engine or Nascar or any other High level motorsport has nothing to do with the Flywheel. Those Flywheels have practially no Mass. Becasue they want all to power to be instantly transfrered from the engine to the drive wheels. If you ever see one stall when launching from the pits it is entirely because their flywheel has no mass.
"a smoother running engine has got to be in the long run, a better choice than one that is trying to run flat out"
Again, you are making assumptions on something that you have no practicle knowledge. If you make a statement like that, please enlighten us as to why it "has got to be". Your statement doesn't even have confidence as fact.
I will admit that I was wrong about one purpose of a flywheel to "Smoothe out an Engine" but I was speaking about flywheels and thier function from my practicle expierence as well as my understanding of their purpose as an engergy storage / transfer device.
"Dont forget its the boy racers, ricer boys in there cars which AINT sports cars which they are trying to soup up.
we dont need to."
I guess that is why the majority of users in this Forum have a list of Improvements to their car listed in their Sig.
#11
Originally posted by W88951
adrian,Do you have ANY practicle expierence with lightened flywheels? Have you ever installed one on your car or any car for that matter?
No, but by the same argument, I aint ever been to the moon, but I know it aint made of swiss cheese.
I get my information from various sources, people, reading previous posts here and on other sites and of course where I've experienced something directly, from personal experience.
Also, if you are going to "quote" a published article, please post a link or a source refernce.
one source was:
http://www.trucktuner.com/tuning/?tS...3&tuningID=58.
I also spoke to one of the guys I work with who has had practical experience of lightening flywheels.
could you also but bold marks around what your quoting back or replying to so I can see what part is mine and what part is your easily, for example
(snip)blah blah blah(unsnip)
that is wrong...
or when replying, use [ b ] and [ / b ] around the text, cheers !
Now, back to the vibration thing. I found several resources mentioning how a flywheel is used to smoothe the power output from a recipricating engine. However, from my practicle expierence with lightened flywheels for automotive use, I never noticed any increase in vibration from the engine due to a lighter flywheel. This is both with 944's and other cars. And when I mean lighter I mean 5~7lbs lighter.
I know in my orginal reply to the original poster, about vibration, may have been incorrectly worded. but the FAQ pointed to the words "smoothes out the engine/cylinder pulses" which is what I re-corrected my syntax with.
following on from that. IF part of the flywheels process is of "smoothing" this out, it follows something which is not smooth, compared with the original is rough"er" ?
And rebuilding an F1 engine or Nascar or any other High level motorsport has nothing to do with the Flywheel.
sorry ignore that, I re-read that bit and it didnt come out as I intended.
What I mean was, Horses for courses, you could divide cars into different uses.
i) Stock build
ii) fast road
iii) track day
iv) rally
v) F1
each have different specs, ways of driving. an F1 car is not ment for road use as neither a stock car suitable for F1, of course you have all the ones in-between.
You have to decide from the outset what you are intending to use your car for, what sort of repairs, how much money, what you will gain and what you are going to sacrifice.
F1 cars are high revving engines, always on the edge, always screaming, never far from 1% fo blowing the hell up. and they always get rebuilt after a race. So you can do any kind of tweeks, as the car is not ment for longevity.
Your Stock 44, is designed as a sports car, fast road car designed to be driven within the confines of being used daily with long service intervals, with no engine strip downs after every day.
It's also designed to be econmical, user friendly, comfortable to drive in both traffic and on motorways (hiways)
rally cars /track day cars etc are road going cars with mods, so that you can get some more out of them for the purpose that you are using it for.
There is not so much of a comfor factor with whizzing rounf a track. The aim is speed and grip. You have a shorter service intervals, so you can get away with more, cos the car gets checked out more often that a STOCK car.
so if you have a harser ride, high revving engine, turbo on full boost its of no consequense as you've weighed up the pro's and cons and costs of repairs rebuilds for what you are doing.
So a lightened flywheel, which will give you a better reving, engine, with faster acceleration speed is better for that purpose. Driving a car in traffic, daily, with 12k between services, with an engine with a gas pedal like an on off switch, which is not as smooth, and more prone to stalling, possible with your mother-in-law having to drive it. May not be the best thing.
"a smoother running engine has got to be in the long run, a better choice than one that is trying to run flat out"
Again, you are making assumptions on something that you have no practicle knowledge. If you make a statement like that, please enlighten us as to why it "has got to be". Your statement doesn't even have confidence as fact.
wear and tear, rebuild costs, MPG, an engine which has less stress on it, lasts longer, or should I say, an engine which is stressed somewhat occasionally lasts longer. Again horses for courses, you dont give a shiiit, if the car just needs to last one race, or not too worried if your track daying the car so your going to dig into your pockets more often to service it.
I will admit that I was wrong about one purpose of a flywheel to "Smoothe out an Engine" but I was speaking about flywheels and thier function from my practicle expierence as well as my understanding of their purpose as an energy storage / transfer device.
The question was about fitting a performance flywheel to a car, which is how I answered it.
"Dont forget its the boy racers, ricer boys in there cars which AINT sports cars which they are trying to soup up.
we dont need to."
I guess that is why the majority of users in this Forum have a list of Improvements to their car listed in their Sig.
Just cos you can does not mean that you should or have to.
And I'm sorry I still stand by that comment, boy racers and ricers have a need to "jack up" there cars, cos they are lacking in something, a Porsche doesnt.
However if somone feels that there Porsche isnt enough, or needs to be more Porsche than what was intended, this is a democracy, so I dont have a problem with that, as long as the person is aware, of the reason and any possible pitfalls of doing an "upgrade" for want of a better word.
adrian,Do you have ANY practicle expierence with lightened flywheels? Have you ever installed one on your car or any car for that matter?
No, but by the same argument, I aint ever been to the moon, but I know it aint made of swiss cheese.
I get my information from various sources, people, reading previous posts here and on other sites and of course where I've experienced something directly, from personal experience.
Also, if you are going to "quote" a published article, please post a link or a source refernce.
one source was:
http://www.trucktuner.com/tuning/?tS...3&tuningID=58.
I also spoke to one of the guys I work with who has had practical experience of lightening flywheels.
could you also but bold marks around what your quoting back or replying to so I can see what part is mine and what part is your easily, for example
(snip)blah blah blah(unsnip)
that is wrong...
or when replying, use [ b ] and [ / b ] around the text, cheers !
Now, back to the vibration thing. I found several resources mentioning how a flywheel is used to smoothe the power output from a recipricating engine. However, from my practicle expierence with lightened flywheels for automotive use, I never noticed any increase in vibration from the engine due to a lighter flywheel. This is both with 944's and other cars. And when I mean lighter I mean 5~7lbs lighter.
I know in my orginal reply to the original poster, about vibration, may have been incorrectly worded. but the FAQ pointed to the words "smoothes out the engine/cylinder pulses" which is what I re-corrected my syntax with.
following on from that. IF part of the flywheels process is of "smoothing" this out, it follows something which is not smooth, compared with the original is rough"er" ?
And rebuilding an F1 engine or Nascar or any other High level motorsport has nothing to do with the Flywheel.
sorry ignore that, I re-read that bit and it didnt come out as I intended.
What I mean was, Horses for courses, you could divide cars into different uses.
i) Stock build
ii) fast road
iii) track day
iv) rally
v) F1
each have different specs, ways of driving. an F1 car is not ment for road use as neither a stock car suitable for F1, of course you have all the ones in-between.
You have to decide from the outset what you are intending to use your car for, what sort of repairs, how much money, what you will gain and what you are going to sacrifice.
F1 cars are high revving engines, always on the edge, always screaming, never far from 1% fo blowing the hell up. and they always get rebuilt after a race. So you can do any kind of tweeks, as the car is not ment for longevity.
Your Stock 44, is designed as a sports car, fast road car designed to be driven within the confines of being used daily with long service intervals, with no engine strip downs after every day.
It's also designed to be econmical, user friendly, comfortable to drive in both traffic and on motorways (hiways)
rally cars /track day cars etc are road going cars with mods, so that you can get some more out of them for the purpose that you are using it for.
There is not so much of a comfor factor with whizzing rounf a track. The aim is speed and grip. You have a shorter service intervals, so you can get away with more, cos the car gets checked out more often that a STOCK car.
so if you have a harser ride, high revving engine, turbo on full boost its of no consequense as you've weighed up the pro's and cons and costs of repairs rebuilds for what you are doing.
So a lightened flywheel, which will give you a better reving, engine, with faster acceleration speed is better for that purpose. Driving a car in traffic, daily, with 12k between services, with an engine with a gas pedal like an on off switch, which is not as smooth, and more prone to stalling, possible with your mother-in-law having to drive it. May not be the best thing.
"a smoother running engine has got to be in the long run, a better choice than one that is trying to run flat out"
Again, you are making assumptions on something that you have no practicle knowledge. If you make a statement like that, please enlighten us as to why it "has got to be". Your statement doesn't even have confidence as fact.
wear and tear, rebuild costs, MPG, an engine which has less stress on it, lasts longer, or should I say, an engine which is stressed somewhat occasionally lasts longer. Again horses for courses, you dont give a shiiit, if the car just needs to last one race, or not too worried if your track daying the car so your going to dig into your pockets more often to service it.
I will admit that I was wrong about one purpose of a flywheel to "Smoothe out an Engine" but I was speaking about flywheels and thier function from my practicle expierence as well as my understanding of their purpose as an energy storage / transfer device.
The question was about fitting a performance flywheel to a car, which is how I answered it.
"Dont forget its the boy racers, ricer boys in there cars which AINT sports cars which they are trying to soup up.
we dont need to."
I guess that is why the majority of users in this Forum have a list of Improvements to their car listed in their Sig.
Just cos you can does not mean that you should or have to.
And I'm sorry I still stand by that comment, boy racers and ricers have a need to "jack up" there cars, cos they are lacking in something, a Porsche doesnt.
However if somone feels that there Porsche isnt enough, or needs to be more Porsche than what was intended, this is a democracy, so I dont have a problem with that, as long as the person is aware, of the reason and any possible pitfalls of doing an "upgrade" for want of a better word.
#13
Andy....Andy... Andy.....
I can't believe that you used "F1 engine or Nascar or any other High level motorsport " in the same sentence.
Nascrap has no business being in the same league as F1, or any other "High level motorsport", let alone in the same sentence. I'm gonna have to slap you when I see you.
Dal.
I can't believe that you used "F1 engine or Nascar or any other High level motorsport " in the same sentence.
Nascrap has no business being in the same league as F1, or any other "High level motorsport", let alone in the same sentence. I'm gonna have to slap you when I see you.
Dal.