Lightened flywheel and pros and cons...

So there is a WRX that I have my eye set firmly on and a friend and I are having somewhat of a debate about whether or not to leave a lightened flywheel in it. It has very basic mods (maybe a stage 2), but one thing the previous owner did was throw an ACT clutch and flywheel into it. My question is if this will cause any kind of damage or if there will be any adverse effects from leaving it in the car, or if the general consensus is to swap the factory flywheel back into it. It is still running the original 02 tranny in it. Any feedback will be awesome guys, thanks.

 

no damage is going to happen to it. it will be a little different driving it. i have one in my 03. it will cause missfire codes every now and again. If its only stage 2 then i dont see much performance gains coming from it. I dont think its worth the time or money to swap out the lightened one for the stock one again. i would just leave it,

 

i have the 11 lb in mine...i love it

 

not quite sure how a flywheel would cause a misfire.. maybe over-revving to fast or something.... but then that would be the drivers error...

 

its a subaru thing with the the crank angle sensor or some crap. it just does random codes. search in nasioc and u will see

 

The owner right now told me about the same problem. I think it has something to do with the crank sensor or a knock sensor.... fastwrx.com has a warning posted in the flywheel sales section about it as a warning that they will not offer refunds for such a problem, so I guess it's well-known... Thanks for the input guys, I'm heading down to pick it up in about an hour

 

I could be wrong but my understanding about them are that lightened flywheels are fine but going too light will allow the RPMs to slow down too quickly. This makes the crank sensor think that a misfire event occured. ACT flywheels are known to be really light... I think about 11-12 lbs (OEM is about 30 lbs.).

This problem can be alleviated by keeping the OEM crank pulley and/or using a bit heavier flywheel... maybe 15-16 lbs. Exedy flywheels are that weight to eliminate the CEL.

Also, lightened flywheels are not good for fuel economy or drivability but they allow the engine to rev freely and shifting is much smoother in a racing environment.

 

yes...but i haven't had any problems yet! haha...i have a light weight 10.4lbs ACT flywheel with a 1.1lbs crank pulley...and the stage one act clutch...well..nothing is going wrong...does have a lot power, feels good! but i dont have a wrx...or so...just a NA powered! like a wrx...heheh

 

When I needed a new clutch, I also opted for the lightweight flywheel.
I love it!
As for drivability issues, I don't know, a new clutch could have taken getting used to as much as the flywheel.
My but dyno says the car pulls harder (faster), especially in 3rd gear.

I asked for recomendations when I had it done, and everyone suggested against the pro light, so I went streetlight instead.

Now having gotten used to the streetlight, I kind of wonder how the prolight would have been...I don't think I would have a problem driving it, but then I don't often find myself in traffic jams or stop and go traffic.

Never once yet have I found myself wanting the big heavy wheel back.

 

I have a ~15lb wheel in the RS. I wanted to stay away from the 10-11lb wheels due to issues in the winter (getting traction in slick conditions is much more difficult with less flywheel momentum) as I was daily driving the car at the time. I have been very happy with it. The tranny/clutch has been abused in the car (strictly an AutoX/Track car for the past 4 years) without an issue.

 

the light flywheel is very good! well..mines i had to take sometime to actually learn the clutch ...then learn the flywheel...since it drops the revs very fast! but i've loved it! it makes the car pulls soo fast! and im not having no problems with it at all!

 

I have a prostreet forged steel flywheel 14.75 lbs. I like it. Revs better than stock and isn't too hard to drive. Never had an issue with codes either.

 

My lightend flywheel experience non-subaru is that it rev'd much faster from a start, but consequently on down shifts from high speeds it lose's a lot of momentum and the car does not accelerate very quickly like a stock weight would. So basically accelerating up is good, but up, down and than up is going to take a little more work. (Note: This is on a 10k rpm Honda motor-power in the high rev range.) I think a good compromise would be something less than stock.

 

Thanks for all the input and different angles guys, I just got the car home from a 300+ mile drive with no problems, the car kicks ass! I'll post pics soon.

 

You will loose rotational mass and momentum. As long as the thing is balanced right there are no adverse effects. although with less momentum it will be hard for crawling over rocks

 

*Bump*

Would a Lighten Flywheel be a good investment while doing an engine build?

EJ257 Block on a Stock 5spd w/ a ACT stage2 clutch kit

 

After running it for a year, I will honestly say yes. Once you get it tuned/reflashed, your check engine codes should disappear. Mine did.

 

^^^
You don't 'tune' out the lighten flywheel.
The latest ecu roms should 'kinda' fix it.

 

More input from me:

I heard about all the warnings about the CAS but went ahead and did the Exedy JDM-spec flywheel (12 pound) along with my UD Vishnu Pulley. I had absolutely no problems with my Stage 2 WRX. Coupled with my RA gears it was an absolute blast to drive and rocketing through the gears was so much fun. Driveability suffered only in the fact that I had to rev a little more and slip a little more to get smooth launches during daily driving. However drag launches were a LOT more difficult.

Would buy again. When the clutch goes out in the Legacy I'll be grabbing a WRX PP/FW combo with the same setup again, for sure.

 

My 9 lb flywheel coupled with the Hyper Single can be tricky sometimes. As long as you are ok with feeling like a ******* sometimes its alright.

 

I'm still cool with mine...

 

I'm afraid lightweight flywheels might make you lose power. Because there is less load which means the turbo doesn't have time to spool. I've done 160mph with the car sitting on the lift. NO BOOST!!!

 

^ You have no idea what you are talking about. Load when you are freewheeling doesn't matter. I made the same or more power when I went from the stock clutch/flywheel to the extremly light Exedy setup that I have now.

 

I thought it was the same concept as putting on a lighter pulley.

 

It is the same concept. Don't worry about how much boost you can make in neutral or the whole car freewheeling. You need resistance(load) for the engine to put enough energy in the exhaust to spool the turbo. I make zero boost in neutral reving it up.

 

You will get less load with a light flywheel becuase your engine is now moving less mass. Saying that's bad is like asking for a heavier car. If you're losing boost becuase of this, you need your tune adjusted.

 

I have a 9 pounder and getting a check engine light with a code of 1 and 3 misfire. Thinking of engine tuning........Have not yet done any sort of reflash. I drive an 03 with 67,000.

 

Yeah you might wanna check that out ...

 

Does it seem to happen more when the engine is cold. Mine does that when the engine is cold and I give it a bit to much gas starting out.

 

I used to have an 8lb flywheel in my prelude, it was almost 25lbs lighter than stock and it discouraged anyone from driving it since they always killed it.

 

LOL from what I have been reading a lighter flywheel REQUIRES a new tune or else your engine/turbo may run like poop and throw codes a lot

 

I can't say it runs like poop, but it does keep throwing the same code. I have several mechanical mods and I guess it time to put it all together with a reflash.

 

Your car shouldn't be running like poop with a lightened flywheel, even without a tune.
But your car will still throw a misfire code.
Get use to it.

 

My car ran fine with the light flywheel, but I was getting CEL with misfires on all cylinders every 3 days or so. After reflashing, I barely ever see them.

 

FWIW I only ran my Lightened and Underdriven pulley on my Stage 2-tuned car. I never had the CEL problem with it. Even while running the shorter-ratio RA gears. Oh man I miss that car...

 

I miss you. Where are you?

 

Home.

 

speaking of issues. I did a up-pipe installation for a customer this weekend. Apparently the up-pipe was in previously but he took it out due to misfire codes. Evidentially the combination of the up-pipe and lightweight flywheel caused misfires before. (I didn't know/didn't recall he had that issues before and took the aftermarket up-pipe out because of it.)

So...lightweight flywheel + up-pipe on a 2002 wrx can cause the CEL to read misfires. According to the customer his flywheel is 10lb range...

He didn't have issues with the flwheel alone, just with the up-pipe and less restriction....strange:ugh:

 

mkay...the first mod I did to my 02' was a streetlite flywheel/exedy stage 1 (organic) clutch. The clutch was going and I figured I'd add a flywheel, since the tranny was coming off anyway.
This was 2-3 years ago, and the car threw a misfire code here and there.

A couple weeks ago, put my TBE, ported manifolds, and up-pipe, got a tune and haven't had a code since.

My advice:
If launches are you're thing, stick with the stock flywheel, and save for ppg's (Andrewtech actually recomends a light flywheel to maximize life of the stock transmission).
With the light flywheel, it is easier to bog the engine if you don't slip it just right...but when you do slip it just right, it's like you're coming out of a slingshot.

 

Mine has given me no ill effects in almost 100k miles, though if i were to do it all again, i wouldnt have gotten it that light (11 lbs) its very hard to launch

 

scuba steve....
actually, the up pipe came out so I would not get a denial of warranty on the transmission syncros and viscous coupler problems that I had. I had heard that if you have an up pipe/down pipe install that they would claim abuse and over modification. Since then I had not reinstalled the up pipe, but they had redone my syncros and transfer case. But back to the original problem...the CEL. That has started rearing its ugly head since the flywheel and new clutch install. The up pipe reinstall has only increased the frequency of the same CEL code. Now it's almost instantaneously re-occuring after clearing. From what I can gather, it is the knock sensor hearing the combustion and calling it a knock and thus a misfire on 1 and 3. I never use less than 91 octane, 99 percent of the time its 92 octane in my tank. Is there a way to desensatize the knock sensor?

 

What code are you getting...one for knock, or misfire?
I belive misfires are interpreted by sudden decelleration of crank speed (in some models anyways).

 

Misfire on 1 and 3. Before you ask....I swapped plugs. I also swapped the coil packs from one side of the engine to the other, cleared the codes, and then immediately got the same codes;1 and 3.

 

Does youre code reader give you freeze frame data?
Anytime my car (an 02' wrx) gave me misfire codes (I've had em on all 4) the freeze frame data that went with the codes revealed that the car wasn't all the way warmed up (coolant below 160) and RPM's were low, most of the time it said the car was going 0mph at the time:ugh:.

I'm going to guess if you are slow getting the car into gear the flywheel drops rpms fast enought to be interpreted as a misfire.

 

and the plugs?