Lightened Flywheel Survey

[vantageX]

Ok since this is car talk, lets talk about one of the more common mods out there, a lightened flywheel. I've seen a post on here that recommended getting a flywheel lightened to increase power. Fair enough, you lighten the flywheel, reduce parasitic drag and free a few horses.

Now my question to you guys out there who have done this mod is; Are you happy with the gains and also the consequences of this mod?

Let's face it, a lightened flywheel will free up a few horses but it also frees up your RPM meaning your RPM drops more rapidly between gear changes hence you find yourself changing gears as fast as a sequential box on an F1 car (or at least trying to):confused_smile: So you're shifting fast all the time, your pick-up has improved but you're accelerating fast all the time, do you really need that?

So should this mod be recommended to beginners of this hobby? Is it worthwhile or are the gains too little to justify and in the long run its just not worth it for a street car? :shades_smile:

 

[BLaCkHoWLiNG]

What car do u drive? end of the day, what objective do u wanna achieve? lightening flywheel aint cheap.. perhaps there's a work-around

 

[g88]

Hope this will help you.

http://www.whizwheels.com/Tips/lightenflywheel.html

http://www.se-r.net/engine/light_flywheels.html

 

[SkYwAlKeR]

if u want, dont lightened too much... u will lose ur top speed... i heard some sifoo said before, lightened max 10% of ur original flywheel weight.... or 5% max??... forget oledi lor... hahaha...

besides, lightening too much will cause it to crack... beware dude.... my advice, get a better clutch kit.... only lightening flywheel cant give much help...

 

[vantageX]

Guys, I don't want to lighten my flywheel. Was just seeking opinions here from people who have done it because I saw another post on here where a guy (newbie) asks what he can do to gain more power and one of the responses was to lighten the flywheel.

Just wondering if this is really a tip that should be given to a newbie without the fella knowing the consequences of lightening a flywheel.

I have my own opinions of the subject which are if I was driving something I wanted to modify I would lighten the flywheel only after I've done other mods and even then I wouldn't lighten it that much, just enought to free a few revs and then I would get it balanced. But that's me...what about the rest of you? Opinions?

 

[koolspyda]

search the topics "lightening with aftermarket flywheels" & "lighten flywheel by skimming"

The former works well & has non the problems that plague the latter; NA or FI. (so not to be misunderstood with local perception that "Lightened Flywheel" will lose on power on uphill.

"power gains"? you achieve higher RPM much faster. if one's car torque is need higher revs to built then using a proper aftermarker flywheel is recommended.

matching with a compatible clutch is also important to reap the benefits of an aftermarket flywheel.

there are others here who swears by "their lightened flywheel" by skimming the stock flywheel. I have not done the avenue & have no expert opinion on that but from what i hear, there are unscrupulous guys have skimmed too much (in the hope to shelved metal in lightening) the stock flywheel cracks under pressure/load; so its your choise to choose wisely.

the cheapest avenue to launch HP into your car is laughing gas /NOZ. new aftermarket flywheels are not cheap. Turbo guys normaly shun "lighten" flywheels as the staying "boost" is enough to satisfy their addiction to speed/power AND on occasions the load form boost do sometimes overwhelms too light a flywheel.

guys who prefer NA utilises lighten aftermarket flywheels more. (construction of these flywheels are from billet material, Forged Chrome-Alloy Steel, aluminium & etc.)

 

[12oY]

but lighten flywheel will reduce torque but gaining afew hp... so when going up hill abit low power.....

 

[vantageX]

I don't really see how lightening a flywheel can reduce torque. It can however free up a few horses because the flywheel causes parasatic drag, the same way an alternator, air-cond compressor, power-steering pump and engine operated fan do. On old cars, one way to gain power was to remove the engine run fan and replace it with an electric fan. This was claimed to free up 1-2bhp.

Same way lightening a flywheel will reduce parasitic drag on an engine and free up some horsepower.

Anyway back to my point in the first post about shifting fast with a lightened flywheel. Going uphill and its a bit low on power? Isn't this down to driving style and the person who is driving the car isn't shifting down fast enough to make up for the revs dropping at a higher speed? The revs do drop faster with a lightened flywheel right?

So conclusion? Not a good mod to recommend to beginners?

 

[Doink]

my iswara uses super touring flywheel skimmed max...kau kau light...pick up damn power...can chase my friends mivec in first and second gear...chase only not overtake...but if carry a lot of load in the car will need to press a lot of fuel...get it...

 

[Dino@Casper]

U will lose torque.. why.. cause torque is depending on ur mass ... the formula for torque=Ia...

where I is ur second moment of inertia which is actually something like mass X radius X radius... can't remember the formula for solid disc but there is definetely a mass there...

And than "a" is ur angular accelaration.. so the lighter the less torque.. but also there would also be less counter torque so there fore the car can pick up easier.. why u loose top speed.. cause there is less rolling momentum to keep ur engine spinning

 

[vantageX]

Well, if you put it that way then it does make sense...wait...I think (scratches head) Man, I sucked at this in college...

But really, thanks for that, it made sense. The real important number here is the angular acceleration. Most of the stuff I read speak of removing the weight from the outer or the inner parts of the flywheel and this influences the power/torque delivery. From your explanation it can be seen that its really the angular acceleration that matters and this can be influenced by where the weight is removed from. (damn, that sounded confusing)

 

[fritz]

Yes..u confirm will lose some torque. Its because the mass is lesser and the inertia forces will be lowered. From this, momentum of ur flywheel will drop.
Just assume u use 2 diff rolling disc and hang it up. 1 with 1kg and another with mayb 2-3kg. U spin it together by applying the same force. When u trying to accelerate the disc, i guess u know the answer that accelerating the 2-3kg disc is easier than the 1kg..right?
This is wat my lect told..hehe..

 

[Dino@Casper]

Fritz, are u sure accelerating the 2kg disc would be easier... i think maintaining the speed at certain rpm would be easier.. same theory with pushing a 1kg block n 2kg block.. surely it would be easier to push the 1kg block..

 

[SataniC]

basket early morning headache reading maths....ahahhahahaha....im using skimmed flywheel on my car....been a year already...still in good shape last time i checked....car definitely feels lighter...and yes...sometimes i do shift gear fast to make sure on above 5.8k rpm....and maybe becos my car have enough torque that i dont need to downshift much when going up genting....hope that helps

 

[xtremeleo]

Yes..u confirm will lose some torque. Its because the mass is lesser and the inertia forces will be lowered. From this, momentum of ur flywheel will drop.
Just assume u use 2 diff rolling disc and hang it up. 1 with 1kg and another with mayb 2-3kg. U spin it together by applying the same force. When u trying to accelerate the disc, i guess u know the answer that accelerating the 2-3kg disc is easier than the 1kg..right?
This is wat my lect told..hehe..

i dunno where u got dis fact, but its the other way around. inertia is an ability dat anything wit mass has to fight the force dat acts on it, wether its stationary or in motion. meaning : high inertia, which if two objects have the SAME dimension, but different weights (mass*gravity acceleration), A being less in weight, less energy is required to move a compared to B (heavier compared to object A), so if the SAME power (energy per unit time) is applied to both to move them, A is no doubt gonna move 1st and gonna accelerate faster den B IF continous power is applied. comprende?
so, lightening the flywheel actually doesnt free any horses, but makes ur flywheel easier to move hence the increase in pickup. whoever says dat lightening flywheel will decrease ur top end is supposed to add the word "excessively" in their sentence because std flywheel was made dat heavy (edited) for smooth gear change ie u dont have to change gear too fast to have a comfy ride. preserving vehicle's motion wit the flywheel's inertia is the keyword. skimming the flywheel excessively wont let ur clutch engage the flywheel optimumly ie has less grip hence the loss of top end which occured because of slips.
horse power on dyno shows increment because of the calculation the dynamometer makes. hp can be measured by acceleration time hence the hp increase on dyno runs after this process.

 

[12oY]

errr... i kind of confusing........... how ar?

 

[fritz]

Hm..mayb my english is not good or wat..hehe!
I agreed with xtremeleo, if both disc is stationary, u can spin the lighter one easier than the heavier one. Ok, lets say if both is spinning at 4k rpm, stop applying power to both flywheel. The lighter one will stop faster than the heavier one. So, if u wanna spin both flywheel back to 4k rpm, which would be faster?I guess if my lecturer is not teaching me the wrong thing, the heavier one will.
So, alot of ppl comment that lightened flywheel will be underpower wen going up hill. Don't know im really correct anot, anything mistake please point out. LOL

 

[12oY]

be that that i wana say hahaha......... that y it have more touque than ligther 1...

 

[Dino@Casper]

Its call rolling momentum.. haha.. thats why ur flywheel when heavy.. its doesn't stop rotating so easily... ur lecturer didn't lie.. i think maybe miscommunication... anyways.. better to go for a proper new set of flywheel if you got the cash.. hehe there a reason why its was design like that in the first place.. that is if got cash.. for people who can't afford.. skim only but not 2 much...

 

[fritz]

Ya..everything hav it advantages and disadvantages. Have to sacrifice something to gain other benefits. So, think what u wan.