Lightweigh flywheels
Dec 24, 2005 | 07:49 PM
#18
keep in mind HP DOES NOT increase. just hidden power that was already there, your just getting that hidden power to the wheels now. It is worth it if your racing but not on the street in my opinion.
Dec 24, 2005 | 07:58 PM
#19
"every pound you remove from the rotating mass of the engine translates into horsepower"
"driveability is changed substantially, especially with any sort of unsprung clutch"
"a lighter flywheel will add wear to your syncros for a daily driven car."
Where are you guys getting your information? I don't mean to pick on you, but I don't people to get the wrong info either.
1. Removing mass will not increase HP, it may increase acceleration especially in lower gears, because it puts less power in storage (less inertia), but it doesn't create power, it makes it usable for acceleration instead of inertia. On a underpowered econobox cruising up a steep hill in 5th, it will actually work against you because you may need the inertia to sustain the rpm longer. Does that mean a lighter flywheel is taking away HP in that case? Of course not.
2. An unsprung disc doesn't affect driveability at all. It affects noise by transmitting more torsional vibrations, but on a race disc it will actually engage smoother (less chatter) than spring center.
3. Lighter flywheel will not increase syncro wear. It will increase other wear possibly, but not syncros. In some cases it reduces syncro wear because the engine rpm rises and drops faster which means that the engine rpm is quicker to match the rpm of the next gear.
"driveability is changed substantially, especially with any sort of unsprung clutch"
"a lighter flywheel will add wear to your syncros for a daily driven car."
Where are you guys getting your information? I don't mean to pick on you, but I don't people to get the wrong info either.
1. Removing mass will not increase HP, it may increase acceleration especially in lower gears, because it puts less power in storage (less inertia), but it doesn't create power, it makes it usable for acceleration instead of inertia. On a underpowered econobox cruising up a steep hill in 5th, it will actually work against you because you may need the inertia to sustain the rpm longer. Does that mean a lighter flywheel is taking away HP in that case? Of course not.
2. An unsprung disc doesn't affect driveability at all. It affects noise by transmitting more torsional vibrations, but on a race disc it will actually engage smoother (less chatter) than spring center.
3. Lighter flywheel will not increase syncro wear. It will increase other wear possibly, but not syncros. In some cases it reduces syncro wear because the engine rpm rises and drops faster which means that the engine rpm is quicker to match the rpm of the next gear.
Last edited by ACTman; Dec 24, 2005 at 08:03 PM.
Dec 24, 2005 | 08:10 PM
#20
Newbie
Joined: Dec 2005
Posts: 18
Likes: 0
From: Orlando, Florida
Originally Posted by ACTman
2. An unsprung disc doesn't affect driveability at all. It affects noise by transmitting more torsional vibrations, but on a race disc it will actually engage smoother (less chatter) than spring center.
I'm just getting my information from the countless number of clutch setups driven and installed. Unless there is some underlying factor that I'm missing, I don't know what to attribute the change in driveability to other than the disk?
However, my ears are open to learn and discuss, so please explain!
Last edited by EnjukuTeddy; Dec 24, 2005 at 08:15 PM.
Dec 24, 2005 | 08:27 PM
#21
Evolved Member
Joined: Nov 2003
Posts: 1,496
Likes: 0
From: Bangkok
The flywheel takes energy to spin up and because of its inertia it will tend to stay at that speed. It's manily there to damp out the torque pulses, things going on when you change gears etc.
A flywheel with greater (polar) inertia takes more energy to spin up than a lower inertia one. The effect is that the car with the a lower inertia flywheel will accelerate and rev up quicker. Actual hp figures will not increase. It's like towing a heavy trailer wouldn't decrease your hp but you accelerate more slowly.
A lower inertia flywheel will also decelerate quicker (cos less energy is stored), so when you lift the accelerator, engine revs will reduce quicker. So yes, drivability will change cos when you chage gears the revs will reduce much quicker. So when you change gears there will likely be a larger difference in the rpms of the various shafts thus increases synchro wear. But this wear can be reduced if you change gears more quickly or change your driving habits. If you heel-toe, or double de-clutch this will be to your advantage as the engine will repond quicker to your right foot.
The thing is, a lower inertia flywheel is generally a good thing but it really depends on how much lower than stock we're talking about. If you're on the street, only use ones which are slightly lower inertia than stock, while if you're only drag racing go as low as you can. In hill-climb races, light flywheels are a no-no. Again, driving techniques will also be a factor.
As a side note, a lighter flywheel will likely have lower inertia, but it's not the case. Basically the polar inertia is calculated from where the mass is multiplied by the radial distance squared so it is possible to make a lighter flywheel with the same polar inertia. This will have the effect of only making your car lighter.
A flywheel with greater (polar) inertia takes more energy to spin up than a lower inertia one. The effect is that the car with the a lower inertia flywheel will accelerate and rev up quicker. Actual hp figures will not increase. It's like towing a heavy trailer wouldn't decrease your hp but you accelerate more slowly.
A lower inertia flywheel will also decelerate quicker (cos less energy is stored), so when you lift the accelerator, engine revs will reduce quicker. So yes, drivability will change cos when you chage gears the revs will reduce much quicker. So when you change gears there will likely be a larger difference in the rpms of the various shafts thus increases synchro wear. But this wear can be reduced if you change gears more quickly or change your driving habits. If you heel-toe, or double de-clutch this will be to your advantage as the engine will repond quicker to your right foot.
The thing is, a lower inertia flywheel is generally a good thing but it really depends on how much lower than stock we're talking about. If you're on the street, only use ones which are slightly lower inertia than stock, while if you're only drag racing go as low as you can. In hill-climb races, light flywheels are a no-no. Again, driving techniques will also be a factor.
As a side note, a lighter flywheel will likely have lower inertia, but it's not the case. Basically the polar inertia is calculated from where the mass is multiplied by the radial distance squared so it is possible to make a lighter flywheel with the same polar inertia. This will have the effect of only making your car lighter.
Last edited by x838nwy; Dec 24, 2005 at 09:01 PM. Reason: cutting it down to size!!!
Dec 24, 2005 | 08:36 PM
#22
Thread Starter
Evolved Member
Joined: Mar 2004
Posts: 1,041
Likes: 1
I heard that heavier flywheels are good for drag racing and lighter for road racing.
I read at a car forum that lightened flywheels can harm the top end power/ acceleration...
What do you suggest for an open road, no speed limit road?
could you explain more: In hill-climb races, light flywheels are a no-no...
Stock 14.5lbs
Exedy 12lbs
Pro street 10.5
FIndanza 9.7lbs I think
I read at a car forum that lightened flywheels can harm the top end power/ acceleration...
What do you suggest for an open road, no speed limit road?
could you explain more: In hill-climb races, light flywheels are a no-no...
Stock 14.5lbs
Exedy 12lbs
Pro street 10.5
FIndanza 9.7lbs I think
Dec 24, 2005 | 08:38 PM
#23
Evolved Member
Joined: Nov 2003
Posts: 1,496
Likes: 0
From: Bangkok
Originally Posted by EnjukuTeddy
More 'torsional vibrations' or not, how does removing a spring center with a solid center not affect driveability on a standard clutch setup? So with the same theory I could run the same X pressure plate just with an iron hub center disk and not decrease driveability?
I'm just getting my information from the countless number of clutch setups driven and installed. Unless there is some underlying factor that I'm missing, I don't know what to attribute the change in driveability to other than the disk?
However, my ears are open to learn and discuss, so please explain!
I'm just getting my information from the countless number of clutch setups driven and installed. Unless there is some underlying factor that I'm missing, I don't know what to attribute the change in driveability to other than the disk?
However, my ears are open to learn and discuss, so please explain!
Race clutches generally grab harder and quicker, no damping the car will jerk forward which is not good if you're in traffic with a coffee in your hand.
Dec 24, 2005 | 08:40 PM
#24
Evolved Member
Joined: Nov 2005
Posts: 905
Likes: 0
From: benson, nc
Originally Posted by x838nwy
Okay, this is going to be long, but I think it will answer your questions:
The flywheel is an energy storage device. It takes energy to spin it up to speed and because of its inertia it will tend to stay at that speed. It's manily there to damp out the torque pulses, things going on when you change gears etc.
A flywheel with greater (polar) inertia will take more energy to spin up than a lighter one. The effect is that the car with the a lower inertia flywheel will accelerate and rev up quicker. Actual hp figures will not increase. It's like towing a heavy trailer wouldn't decrease your hp but you accelerate more slowly.
While you can spin up the lower inertia flywheel quicker, it will also decelerate quicker (cos less energy is stored), so when you lift the accelerator, engine revs will reduce quicker. So yes, drivability will change 'cos when you chage gears the revs will reduce much quicker. So when you change gears there will likely be a larger difference in the rpms of the various shafts thus increases synchro wear. But this wear can be reduced if you change gears more quickly or change your driving habits. In any case if you heel-toe, or double de-clutch this will be to your advantage as the engine will repond quicker to your right foot.
The thing is, a lower inertia flywheel is generally a good thing but it really depends on how much lower than stock we're talking about. If you're on the street, only use ones which are slightly lower inertia than stock, while if you're only drag racing go as low as you can. In hill-climb races, light flywheels are a no-no. Again, driving techniques will also be a factor.
As a side note, a lighter flywheel will likely have lower inertia, but it's not the case. Basically the polar inertia is calculated from where the mass is multiplied by the radial distance squared so it is possible to make a lighter flywheel with the same polar inertia. This will have the effect of only making your car lighter.
The flywheel is an energy storage device. It takes energy to spin it up to speed and because of its inertia it will tend to stay at that speed. It's manily there to damp out the torque pulses, things going on when you change gears etc.
A flywheel with greater (polar) inertia will take more energy to spin up than a lighter one. The effect is that the car with the a lower inertia flywheel will accelerate and rev up quicker. Actual hp figures will not increase. It's like towing a heavy trailer wouldn't decrease your hp but you accelerate more slowly.
While you can spin up the lower inertia flywheel quicker, it will also decelerate quicker (cos less energy is stored), so when you lift the accelerator, engine revs will reduce quicker. So yes, drivability will change 'cos when you chage gears the revs will reduce much quicker. So when you change gears there will likely be a larger difference in the rpms of the various shafts thus increases synchro wear. But this wear can be reduced if you change gears more quickly or change your driving habits. In any case if you heel-toe, or double de-clutch this will be to your advantage as the engine will repond quicker to your right foot.
The thing is, a lower inertia flywheel is generally a good thing but it really depends on how much lower than stock we're talking about. If you're on the street, only use ones which are slightly lower inertia than stock, while if you're only drag racing go as low as you can. In hill-climb races, light flywheels are a no-no. Again, driving techniques will also be a factor.
As a side note, a lighter flywheel will likely have lower inertia, but it's not the case. Basically the polar inertia is calculated from where the mass is multiplied by the radial distance squared so it is possible to make a lighter flywheel with the same polar inertia. This will have the effect of only making your car lighter.
what i understand from a lighter flywheel is that you have to shift quicker and have more control of the gas pedal, thats it, basically work on being a more precise driver.
Dec 24, 2005 | 08:52 PM
#25
Evolved Member
Joined: Nov 2003
Posts: 1,496
Likes: 0
From: Bangkok
Originally Posted by k270kmh
I heard that heavier flywheels are good for drag racing and lighter for road racing.
I read at a car forum that lightened flywheels can harm the top end power/ acceleration...
What do you suggest for an open road, no speed limit road?
could you explain more: In hill-climb races, light flywheels are a no-no...
Stock 14.5lbs
Exedy 12lbs
Pro street 10.5
FIndanza 9.7lbs I think
I read at a car forum that lightened flywheels can harm the top end power/ acceleration...
What do you suggest for an open road, no speed limit road?
could you explain more: In hill-climb races, light flywheels are a no-no...
Stock 14.5lbs
Exedy 12lbs
Pro street 10.5
FIndanza 9.7lbs I think
Road racing: Depends on the track, but generally lighter would be good.
Hill-climb: When you change up gears on the incline, your car wants to slow down anyway. So when you press the clutch pedal to change up with a light flywheel, the revs will die very quickly. Now if by the time you lift up the clutch pedal, the revs has gone too low, the car is going to bog down. The incline will amplify this effect, the reduced inertia of the engine will also let the engine be slowed down by the transmission more. You can drive around this with heel/toeing etc. but it's going to be difficult.
I did a bit of racing with Integras and Civics years back and for those thing we found the best flywheel for most tracks was one only slightly lighter than stock, like 3-4lbs. But that's with a racing clutch assembly so on the whole it was probably much lighter...
I haven't played around with the evo's clutch so I can't really say which is best, but I've never been disappointed with Exedy stuff...
Dec 24, 2005 | 08:53 PM
#26
Newbie
Joined: Dec 2005
Posts: 18
Likes: 0
From: Orlando, Florida
Originally Posted by x838nwy
The sprung plate is there to damp out torsional vibrations. That's not just audible noise, but the actual vibrations resulting from engaging and disengaging the clutch. Removing the sprung centre will make the clutch engagement MORE jerky.
That's why I was interested in the alternative theory that ACTman proposed.
Dec 24, 2005 | 08:55 PM
#27
Evolved Member
Joined: Nov 2003
Posts: 1,496
Likes: 0
From: Bangkok
Originally Posted by alloyic_rs
good explanation but i think there's more big words in there than needed, you could probly shorten that into one lil paragraph instead of five.
what i understand from a lighter flywheel is that you have to shift quicker and have more control of the gas pedal, thats it, basically work on being a more precise driver.
what i understand from a lighter flywheel is that you have to shift quicker and have more control of the gas pedal, thats it, basically work on being a more precise driver.
Admittedly, I do have a habit of really long posts...quickly edited it. any better?
Last edited by x838nwy; Dec 24, 2005 at 09:00 PM.
Dec 24, 2005 | 09:20 PM
#28
Originally Posted by EnjukuTeddy
Exactly my point.
That's why I was interested in the alternative theory that ACTman proposed.
That's why I was interested in the alternative theory that ACTman proposed.
