lightweight vs. stock flywheel

[timtiminy]

hey i have heard conflicting oppinions on what flywheel to use on the SR20DET motor. I hear that having a lightweight flywheel gets you into boost faster but it also falls off quicker when shifting and the stock one has the inertia to keep the motor spinning and the turbo spooled, as well as the inertia to help on take off. Are the benefits of a lightweight flywheel worth its downfalls?

[BoostedCoupe]

from what i got from this thread from brian is that it helps rev faster and the revs fall down quicker. if you understand what im saying. I dont see were it would effect boost but with the motor having to spin less weight which allows it to reach peak boost quicker.
http://www.zilvia.net/f/showthread.php?t=187294

[HalveBlue]

Simple physics.

Less mass is easier to move but will also slow down more quickly.

Personally, I like the ability to have my engine rev up a little bit quicker.

[timtiminy]

so slowing down more quickly would mean that you would drop out of boost correct? I wonder how much of a difference there really is, I havent felt the difference first hand yet, my dad is putting a fidanza on his celica gts this week so i guess i can figure out which way i want to go once i see how it compares first hand. but dang that 2zzge motor already revs like crazy so if it does make a noticable difference it should be pretty nice.

[HalveBlue]

No. Boost pressure isn't regulated by the flywheel.

If the flywheel is slowing down it's because your transmission is not engaged (geared in neutral) or because you're slowing down in gear. In neither case are you building boost.

Essentially, a heavier flywheel will tend to slow down more slowly. That means that you wont loose as many revs in between shifts. But this is obviously offset by the fact that a lighter flywheel will rotate more quickly therefore reaching higher revs more quickly.

Hope that makes sense, I'm pretty tired.

[bo2o]

you loose torque nuff said.

easier to get in spool, but wont have that jump as much or pull kinda of feeling

[HalveBlue]

Originally Posted by 96Turbo

not correct. a heavier flywheel takes more energy to get moving the same speed as the lighter one (thus taking longer), but once it's spinning the same speed, it will slow down slower than the lightened one. This is because it has a higher rotational inertia. So between shifts you will have a drop in rpm's with the lightened f-wheel compared to stock.

I have no experience with the feeling of driving one, but that's my $.02 from a physics perspective

Uh, I'm pretty sure that's exactly what I wrote. But maybe the sentence structure was too hard to read. Whatever. It's late. And I'm flying to Germany tomorrow.

So, peace out.

[96Turbo]

wow, not sure what the hell i was doing there.....i completely miss understood your post. think i should get some sleep too. sorry to question your explanation when it was exactly right. shiiiiiit. i need more sleep, less studying & less smoking

[HalveBlue]

NP, dood. Happens to the best of us.

[Addicted2Kouki]

Another alternative is to get your stock flywheel lightened by a machine shop.
Essentially, almost the best of both worlds... just its the in between.

[SoguRacing]

Launching with a lighter flywheel will be noticeably harder due to the fact that there is less rotating which means less inertia = less rotating momentum. With a heavier flywheel launching will be easier due to the fact that there is "more" rotating mass which means your engine will have more rotational momentum at the flywheel.

[S14DB]

Originally Posted by Addicted2Kouki

Another alternative is to get your stock flywheel lightened by a machine shop.
Essentially, almost the best of both worlds... just its the in between.

wouldn't have any idiot do that or you'll have chunks of flywheel in our legs.

Originally Posted by bo2o

you loose torque nuff said.

easier to get in spool, but wont have that jump as much or pull kinda of feeling

you don't loose tq. you loose rotational mass. makes it feel laggy when you engage the clutch.

[91SuperS13]

You wont really feel a huge difference with just the fly wheel. On average a light weight flly wheel is about 10lbs lighter than stock.

Now match that light weight fly wheel up with a light weight drive shaft and you'll really feel a difference in the quickness of accelleration.

[SoguRacing]

Once again..Rotational Mass...

[tt99ol]

it feels nice, revs quicker, noticable difference, clutch kicks are easier as it revs alot more with the same kick as stock, you do sacrifice some bottom end but losses are minimal while you open up mid/top power, the car revs smoother past 4-5k and pulls alot harder near redline
once your in boost its better than stock but outside of boost it has less torque but revs quicker
try it unless you plan on drag racing, act prolite is nice, 10.5lbs and chromoly not that crappy aluminum with inserts and is probably cheaper than most with great quality

[sillyvia13]

I have a na ka...
alum crank pulley
alum flywheel
Alum driveshaft
and alum wheels
much fun...its as fun as a stock sr20det..
from a na ka...
I need to make a video to show ya...revs like a street bike...I find my self back peddling alot in corners I would normally WOT through....
do it...best bang for ya buck...
I was sad about low end loss, but you dont use it when racing and shit...
PLUS I also drive in 5th gear on 30 mph zones...gas mileage is NICE!!!!

[DreamN]

^ curious, how's the noise with the alum. drive shaft? Is it a DSS drive shaft?

[sillyvia13]

Originally Posted by DreamN

^ curious, how's the noise with the alum. drive shaft? Is it a DSS drive shaft?

WELL SINCE YOU ASKED!!!!!!!! lol

I have soild rear subframe inserts ALUM of course...
and a soild trans bushing...well poly pretty soild...and stock motormounts..and this was a good amount of vibrations..
then once DSS shaft went in...OMG! every little friggin piece of plastic that can make noise does...thats how i found I can drive in 5th doing 35...lol...vibrations go away at 2k rpm...lol...

It is noisy...I have no radio...yet...but all in all. well worth it.
I think I took like 50lbs from drivetrain.
1 lb pulley vs 11lbs
10 lb flywheel vs 25 lbs
dss ds ??? but atleast 15 lbs lighter! and soild no rubber bushing...
and 14 inch ssr alum wheels...mad light!
I love it...more than my sr powered drift car.
KA is my new found love...til I put my rb25 together...

[DreamN]

lol good to know, thank you. what pulley are you using btw?

[timtiminy]

do you think having one will effect rev matching downshifts? making it harder to rev match smoother?

[nismo tuned s14]

my friend HAD a fidanza on his prelude. he had to relearn how to shift because it was harder for him to stay in V-TAK! then less than a year later he was teaching his girl how to drive a 5 speed and she somehow managed to rip 75% of the teeth off the flywheel. but you could tell a difference while it lasted. it chattered a little bit but it wasnt too bad.

[sldbyuramg]

ok well a lightweight flywheel will help you rev faster which in turn will help you reach peak boost faster...but your not going to just all of a sudden drop to vacuum in between shifts. sure if you just let off the gas and held in the clutch for a few seconds but if your quick shifting your not gonna loose all your boost instantly

[S14DB]

Originally Posted by nismo tuned s14

my friend HAD a fidanza on his prelude. he had to relearn how to shift because it was harder for him to stay in V-TAK! then less than a year later he was teaching his girl how to drive a 5 speed and she somehow managed to rip 75% of the teeth off the flywheel. but you could tell a difference while it lasted. it chattered a little bit but it wasnt too bad.

She not know how to start the car? The starting ring is replaceable.

Originally Posted by sldbyuramg

ok well a lightweight flywheel will help you rev faster which in turn will help you reach peak boost faster...but your not going to just all of a sudden drop to vacuum in between shifts. sure if you just let off the gas and held in the clutch for a few seconds but if your quick shifting your not gonna loose all your boost instantly

Yeah, Boost is Dump Valve(WG/BOV) dependent. Your exhaust keeps the turbo spinning. If your turbo is spinning down between shifts you need to look at your Waste gate and Boost control set up.

[handinpants]

Originally Posted by bo2o

you loose torque nuff said.

easier to get in spool, but wont have that jump as much or pull kinda of feeling

i have an act 14lb flywheel and i am making more torque than hp... go figure

[steve shadows]

Originally Posted by timtiminy

lightweight vs. stock flywheel

YES YES YES

do it.

Lightened Flywheel is the way to go. Go with Chromoly, or if you are on a budget the ACT Street is the one I liked the best for the money.

Pair a lighter flywheel with aggressive Cams (HKS STEP2) and a Larger Throttle body and you will have violent and clean throttle response like you wouldnt believe.

Enjoy

[rb25_s13*CHUKI]

Originally Posted by steve shadows

YES YES YES

do it.

Lightened Flywheel is the way to go. Go with Chromoly, or if you are on a budget the ACT Street is the one I liked the best for the money.

Pair a lighter flywheel with aggressive Cams (HKS STEP2) and a Larger Throttle body and you will have violent and clean throttle response like you wouldnt believe.

Enjoy

Throw In some lightweight pullys and a unorthodox main crank pully and you might have too much throttle response!

[rb25_s13*CHUKI]

I had a findanza 9 lb flywheel and act 6 puck un-sprung with extreme pressure plate and I felt almost no drop with shifts and the motor still gave me that pull feeling. **I miss that motor!** get a lightweight flywheel! You wont regret It!

[landins13]

you wanna go superlight get a lightweight driveshaft and a knife edged and lightened crank too. driveshaftshop aluminum driveshaft 9lb flywheel and an xs engineering 14lb crankshaft my motor responds better than my r6

[chibo]

Originally Posted by landins13

driveshaftshop aluminum driveshaft 9lb flywheel and an xs engineering 14lb crankshaft my motor responds better than my r6

Your r6 is broken then.

I have a fidanza flywheel on my car, I hate it. Makes it too touchy driving around in traffic.

I loved the E36 M3 I had with a M5 Clutch and lightweight flywheel, that was pretty much a goddamn awesome car.

[ManoNegra]

I'd go for ~15lbs for a flywheel on a daily driven car
that's what I plan to do on my car
drove a car with a 11lbs one for a while and though it was fun
stop and go traffic was a annoying