turbobrick

Hey all

I recently bought an 09 MT GT, and was thinking about putting a lightened flywheel in it. I don't have any experience with this stuff, and this seems like a safe place to start.

I know the upsides of a lightened flywheel. Are there any downsides?

WVBoosted8

iTrader: (5)

I don't think I would put a lightweight flywheel on if you didn't already need to change the clutch out which might take some time. I have the act prolite and I didn't notice that much of a difference. I could be the only one but I think you can spend your money better in other areas right now.

Jedi54

iTrader: (7)

no drawbacks that I know of.
I agree with WVboosted8 though, it's probably best to do this upgrade if you're changing out a clutch.
unless of course you really just love working on your car.

Huey52

iTrader: (2)

The only downside is that the stock, heavier, flywheel provides a little more inertial mass which aides in starting. But so minor it's not worth being concerned about. The upside of faster spool ups with the lighter flywheel far outweighs this minor downside.

Concur with WV, not really worth doing unless you're also replacing your clutch, as it's allot of work getting in there. Better, and less expensive, things to do first.

c0ldf1ame

iTrader: (5)

it'll be harder to drive,

mysql101

i have the prolight act flywheel. it revs faster, but the talk about harder to drive is not noticeable. it drives just fine. if anything, i'd go for the absolute lightest flywheel possible.

c0ldf1ame

iTrader: (5)

what i noticed is that the revs raise faster, which is a plus, but they also drop faster, which makes it hard to rev match haha, by the time i get the foot on both the brake and gas the rev is already dropped out of the good part of the rpm range =\

ssspeedfreak

iTrader: (1)

Get the BHR fly wheel and spec clutch upgrade, its a nice set up! If you are dling future upgrades you'll be happy you did!

nycgps

iTrader: (1)

- its a bit harder to drive, just need some time to get used to
- rpm revs up faster, but it also drops down faster (cuz its lighter)
- its easier on drivetrain (slightly)

Get something with replaceable fricition plate. so the flywheel will last the life of the car. just change the plate everytime you swap clutch, the friction plate is cheap (compare to a brand new flywheel)

reddozen

iTrader: (1)

you may not want it on a bridge port application. BDC doesn't recommend them for bridge ported cars.

california style

i have a Racing Beat flywheel, and love it.

No real downside, unless you are terrible at clutch control?

mysql101

Like I said, I have the ACT prolite flywheel and don't notice any problems. You can see the rpms climb and drop in this video:

[embed]pUoA0RuD7Pk[/embed]

shazy

wtv. There really isnt any downsides and get the 9 pound one from bhr. Easy as that
You also reduce the drivetrain loss :D

Targatheory

For those who have a lightweight fly, about what rpm are you guys typically starting in first gear? I just put my fidanza in, and now it seems like I have to slip the clutch at like 3k just to start, before it was much less than that.

BDC

The answer to the question is, "it depends on what you're using the car for." If it's your run-of-the-mill street car that won't see any serious straight-line, then a nice, steel lightweight flywheel will be nice. As stated already, it reduces deceleration time in-between gear shifts. It'll also add some "spice and spunk" to the car. If the car is being built for straight-line, use a heavy flywheel. The heavier the flywheel, the more inertia it will have, therefore the easier it is to launch from the tree with more target-RPM consistency. Been there, done that. Also, for those considering a high overlap setup later, I don't recommend a lighter than stock flywheel as the driveline will thrash quite a bit at lower RPM's in taller gears.

B

mysql101

You're driving it wrong then.

You don't need anything above idle to get moving, just slowly let off the clutch and the car will move in first gear. You can slip it more to get moving in 1st, but as you practice you won't need it much.

Of course, if your coils are dying, one of the symptoms is being unable to move the vehicle without reving it up, otherwise it stalls. I've been there and done that

Mawnee

On our Rx8s and with a stock or semistock clutch, shouldnt be an issue at all.

I know with my last car(Built/Procharged C5)I actually removed my aluminum flywheel and went to a lightened steel one(split the difference in wieght). With a very aggressive clutch and the ultra-light flywheel the car was hard to get rolling from a start. It was either push the revs high or it would fall on its face when the clutch instantly grabbed.

BDC

Bingo.

I'm a fan of doing anything within reason to lighten up the rotating assembly for the sake of bringing some low-end to the RE, but going with too light of a flywheel is not a good solution I don't think for the reasons Mawnee just gave. I don't know when and what weight flywheel on the 8 will do that, but I suspect it wouldn't take a lot.

B

shazy

But isn't the point of getting a lighter flywheel to reduce the drivetrain loss and get somewhat more power from it?
Let's take BHR's 9 pound flyhweel for example (since it's the lightest), the people who own this, does it really make a difference in terms of acceleartion and power?

Mawnee

While less load allows the engine to rev more freely, it also carries less momentum when you shift and leave the line. You are essentially trading Torque for responsiveness.

Mawnee

^ Right. But there is a difference between the torque when the clutch is engaged and the inertia carried at the point of engagement.

This is all kind of moot though. As I said, on an Rx8 with a stock or near stock clutch it will never be an issue. We arent using clutches with 850ft/lbs of grabbing force here

A lightwieght flywheel will definetly change the way the car feels to you, and most agree its for the better

mysql101

That's an urban legend, so you have to tread carefully so as to not misinform others.

You do not lose torque from a lightweight flywheel.

http://www.uucmotorwerks.com/flywhee...orque_loss.htm

Mawnee

No offense but we can post up "facts" and spreadsheets to support both sides of this VERY old debate. People on one side will say its bad, those on the other will say its good.

I offered my personal experience of a situation where a lightwieght flywheel becomes a problem. However, I have stated TWICE now that on our car it is a non point anyway and that I am simply pointing out what the counterpoint is.

I am not here to argue or blast holes in others "opinions". I have offered my feedback and experience with lightwieght flywheels. My opinion is really not debatable. You are however free to offer your own opinion.

Mawnee

lol yea, didnt matter on the track. But on the streets leaving lights it was stall the car or chirp the tires to get rolling

shazy

/\ I like chirping the tires Especially in 3rd.