lightened flywheel or standard for street/strip driving

[Guest vf20/21bg5]

Hey guys as most of you know im in the process of planning my semi monster tune build and the next question on my mind is over flywheels....

....250-300kw max atw twisted turbo/link/ballanced/blueprinted forged block etc/sti heads p&p etc...

...i want quick off the mark and quick to spool the garrett gt30....

...so is a 5kg billet flywheel or a standard 10.5kg cast iron flywheel with a max of 1kg shaved off it best for what im after?

[8e4r]

I have a 4.6KG JUN Ultra Lightweight Chromoly Flywheel on my V2 WRX. Cost a fair bit but is still my favourite mod on my car to date .

I've also got lightweight pulleys so the two coupled together make a huge difference in throttle response and climbing quickly up the revs.

Keep in mind though these upgrades DO NOT add more power to your car, simply reduces the load your engine takes to create torque.

If you're chasing pure power then the money could be spent elsewhere but if you want a more responsive car (in terms of throttle response) I'd recommend you get the flywheel upgrade, could even consider some lightweight pulleys as well, hope that helps!

[Guest boostin]

I have a light flywheel and I hate it. Yes it picks up speed quicker, but it also loses it fast. Hill starts are a mission as the engine speed drops too fast once the clutch starts to bite. I'm not one to give it a few thousand rpm then dump the clutch. Too many times I've tried getting out of an intersection only to have the revs drop and the car bogs while a 4WD comes flying at me at 70kph in a 50 zone. I'm over it.

One of my jobs over then next 2 weeks while I'm off work is to pull the gearbox out and fit the standard flywheel I bought around a year ago.

[Guest vf20/21bg5]

well i want a bit of both worlds really....are 7kg flywheels availible? 3kg lower thn standard but 3kg higher than full lightweight

[BC5RA]

 vf20/21bg5 said:

well i want a bit of both worlds really....are 7kg flywheels availible? 3kg lower thn standard but 3kg higher than full lightweight

Standards are about 12kg, at least thats what one weighed out of a V4 STI.

[Guest vf20/21bg5]

 BC5RA']

[quote name='vf20/21bg5 said:

well i want a bit of both worlds really....are 7kg flywheels availible? 3kg lower thn standard but 3kg higher than full lightweight

/quote]

Standards are about 12kg, at least thats what one weighed out of a V4 STI.

....i got 10.4kg frm a spec book but not too sure if thy vary frm models.....maybe thy change after 2000 like most things

[Guest vf20/21bg5]

can anyone tell me if thy have heard of a 6-8kg flywheel avail?

[Guest boostin]

Gimme a couple of weeks and I'll tell you what my flywheel weighs. Its pretty light though.

[BC5RA]

 vf20/21bg5 said:

can anyone tell me if thy have heard of a 6-8kg flywheel avail?

I've seen an 8kg flywheel for sale on TM awhile ago, not sure where you'd get one from sorry.

[Guest vf20/21bg5]

 BC5RA']

[quote name='vf20/21bg5 said:

can anyone tell me if thy have heard of a 6-8kg flywheel avail?

/quote]

I've seen an 8kg flywheel for sale on TM awhile ago, not sure where you'd get one from sorry.

...yes i think the key for a good street medium is certainly an 7-8kg flywheel....will try track one down over the nxt few months and get it skimmed and ballanced 4 my build

[Guest vf20/21bg5]

 boostin said:

Gimme a couple of weeks and I'll tell you what my flywheel weighs. Its pretty light though.

...yep cool let us know but i think yours will be too light for what im after ay....the subaru bible says a good upgrade for street/strip use is a standard 10.4kg flywheel with just 1kg shaved off it (max) makes a good difference but i want at least 3kgs off fron standard

[BC5RA]

I will be going to a 5.3kg flywheel soon, will let you know how that is.

[Stoffa]

talk to someone at your local BNT store, I've got an Extreme clutch combo which came with heavy duty pressure plate and matched 6.3kg chromeolly flywheel.

The cars not running yet so I cant comment on it, but I did read that if you go any lighter than that you can have stalling issues.

after MUCH reading on lightweight pulleys i'm also sticking with my factory harmonic dampner, for the amount of rubber thats in a V5 sti one, I'm sure its a nessacary item.

although many people will think otherwise

[Guest vf20/21bg5]

 Stoffa said:

talk to someone at your local BNT store, I've got an Extreme clutch combo which came with heavy duty pressure plate and matched 6.3kg chromeolly flywheel.

The cars not running yet so I cant comment on it, but I did read that if you go any lighter than that you can have stalling issues.

after MUCH reading on lightweight pulleys i'm also sticking with my factory harmonic dampner, for the amount of rubber thats in a V5 sti one, I'm sure its a nessacary item.

although many people will think otherwise

...6.3kgs a perfect wieght!...as for the harmonic ballencer i would agree for a standed un-ballenced un-blueprinted engine it should be a must ! cause thats why thy make and fit them standard ! .....but because my crank/flywheel/pressure plate and pully's will be expensively ballanced and engine blueprinted ive read/ heard and proven over the years from my builds that i dont really need one....well im yet to have an engine fail due to this upgrade anyway.....im sure if someone dissagrees on here regarding this issue ill hear about it

[BC5RA]

It's like any mod that effects the way the car drives.

You will get used to it in time.

As long as you are the only or main driver of your car then there would be no issues going with a significantly lighter flywheel.

I don't understand the fuss about harmonic damper's what are they dampening?

[Guest boostin]

FYI - its damper, not dampener. Its deadening vibrations, not making it wetter.

http://en.wiktionary.org/wiki/damper

http://en.wiktionary.org/wiki/dampener

[BC5RA]

 boostin said:

FYI - its damper, not dampener. Its deadening vibrations, not making it wetter.

http://en.wiktionary.org/wiki/damper

http://en.wiktionary.org/wiki/dampener

Sorry teach.

[Guest vf20/21bg5]

 BC5RA said:

It's like any mod that effects the way the car drives.

You will get used to it in time.

As long as you are the only or main driver of your car then there would be no issues going with a significantly lighter flywheel.

I don't understand the fuss about harmonic damper's what are they dampening?

...i was told thy put harmonic dampers in from factory as a cost effective way of damping the vibrations thru crank from the factory crank/rods/flywheel/etc (being ever so slightly off ballance) ... basicly anything that is connected to the crank because at the factory they only do a rough ballance b4 fitting.....it costs way too much in time and labour to ballance all these items perfectly .....i always blueprinted and ballanced my engine builds so have never needed one

[Stoffa]

**please note this is MY thoughts on the matter**

harmonic dampers dont have anything to do with the over all balancing of your engine, they are to absorb the torsional twisting that happens to the crank every time a combustion happens.

Torsional vibrations happen kind of like a tuning fork, everytime the fuel is ignited it forces the piston and rod down with such pressure the crank gets torsional twisting.

The rubberised factory damper absorbs these vibrations from getting transmitted back up and down the crank. Even if you have your brand new engine fully balanced (crank, flywheel, clutch and crank pulley) it will still spin balanced but have these bad vibrations in the crank. If these vibrations resonate at the right frequency they will amplify themselves.

as I said i've done alot of reading on it and this is what I believe, I haven't been able to find proof anywhere but its this type of theory that maybe the difference of your engine lasting an extra 20,000kms, you just dont know.

http://en.wikipedia.org/wiki/Torsional_vibration

[Guest vf20/21bg5]

 Stoffa said:

**please note this is MY thoughts on the matter**

harmonic dampeners dont have anything to do with the over all balancing of your engine, they are to absorb the torsional twisting that happens to the crank every time a combustion happens.

Torsional vibrations happen kind of like a tuning fork, everytime the fuel is ignited it forces the piston and rod down with such pressure the crank gets torsional twisting.

The rubberised factory dampener absorbs these vibrations from getting transmitted back up and down the crank. Even if you have your brand new engine fully balanced (crank, flywheel, clutch and crank pulley) it will still spin balanced but have these bad vibrations in the crank. If these vibrations resonate at the right frequency they will amplify themselves.

as I said i've done alot of reading on it and this is what I believe, I haven't been able to find proof anywhere but its this type of theory that maybe the difference of your engine lasting an extra 20,000kms, you just dont know.

http://en.wikipedia.org/wiki/Torsional_vibration

...you have certainly hit the right spot thr m8....you are very correct about the impact and torsional twist on the crank from the combusting action of the engines etc.....i stand corrected from what i said earlier about ballancing being the only cause of vibrations from a crank but do think that if everything on the crank is in perfect ballance and static ballance then that does help a hell of alot towards the overall impact on the crank during its cycle....i certainly wouldnt run a cnc front pully inplace of a harmonic dampner on a stock engine

[Old Skool Subbie]

Well go back to what the factory EA63, EA71, and EA81 engines never had a harmonic dampner. They did extreamly high millages with no problems.

Those engines only had a pressed steel pullys.

Is it something thats needed on a high preformace engine?

I had know a few guys that had run cnc front pullys on there RXs RXIIs, XT6s, SVXs etc never had problems.

[Guest vf20/21bg5]

 Old Skool Subbie said:

Well go back to what the factory EA63, EA71, and EA81 engines never had a harmonic dampner. They did extreamly high millages with no problems.

Those engines only had a pressed steel pullys.

Is it something thats needed on a high preformace engine?

I had know a few guys that had run cnc front pullys on there RXs RXIIs, XT6s, SVXs etc never had problems.

...thats exactly it ay....i havnt heard any proof that not running thm has seen an engine to its fate....hey altho it maybe possible that not having one has helped along other problems develope in the block but not traced to it being the factor....would the vibrations from not having one help wear the mains?....ill leave that one to the fuji heavy scientests to explain

[dubbedup]

i didn't even think subys had a damper at least not like a skyline or similar, i have cnc machined pulley for over a year now with no probs...

[Guest vf20/21bg5]

 dubbedup said:

i didn't even think subys had a damper at least not like a skyline or similar, i have cnc machined pulley for over a year now with no probs...

yep believe it or not alot of cars do have thm...jap and american made....i had a huge one on my 350 chevey engine too

[dubbedup]

aren't the crank pulley solid metal or am i missing something here