lightened or not flywheel

[95talontsi]

Hey I am doing my clutch/tranny and see that my flywheel is a little chewed up ,(damn previous owner) and my goal is to have a low 12's "street" car.
should I buy a lightened one or a oem one cause this is a street car, I would think (but could be wronge) that w/ awd having a heavy flywheel would be good for it, because of the interia it carries, anyone run a lightened flywheel here. But with a lightened flyw I could get into the power band real quick,??? what do you guys think.

 

[CBgst]

I read somewhere that a lightened fly wheel just made the car harder to launch consistently. The guy said the car felt faster with the lighter fly wheel but that didn't translate to faster times at the track. He ended up going back to the stock fly wheel later on. I don't have one so I don't know but I was thinking of buying one and was checking out info on them and that's what I found. Can't remember the web site or I would you in that direction sorry. Hope this helps though.

 

[SPEEDY]

IMHO I think a lightened flywheel would benefit an awd better than a fwd. I tend to think that it would probably make a fwd spin more, therefore making it even harder to launch than it already is. Then on the other hand, I think it would help you awd guy's launch even harder, "better" plus it helps to reduce unsprung weight, which would help the awd, especially since the awd loses so much power due to drivetrain loss.

 

[CBgst]

That's a good point the guy that wrote that review did have a fwd. I would agree that this would defintly benefit an awd more. Fwd are already a pain to launch.

 

[hdswanny]

i have a fidanza fly and i love it. The revs are quicker, resulting in faster spool up. The benefit of a lightened fly is that you reduce the rotating mass by 10+ lbs right from the crank!

for FWD guys, you should love it when racing from a roll due to the quicker revs. There are NO driveability problems whatsoever. FWD guys -- face it, a flywheel won't make you spin your tires. Its your FWD. you need a good suspension and tires to hook up.

The only reason i can think of launching being inconsistent, would be he didn't adjust and get used to driving, and launching his car with the lightened fly. I am a novice driver at best when at the strip, and i managed to pull 3 straight 1.81 60" with this flywheel.

If you do decide to go with a light fly, avoid lightened STOCK ones. They crack and are only 2-3lbs lighter. My fidanza weighs 8-9lbs. There was a long post about this same topic on the "other" forum.

I love mine.

 

[CBgst]

your awd though that's why your launches are consistent. This guy was fwd and he said sometimes it would spin tires if he rev to high but it was quick to bog if he didn't keep the rpm's up. He didn't say you can't launch fwd with a lightened fly wheel he said it was just harder to consistently. Also he claimed to be a veteran driver but who knows. Maybe I'm wrong but to me it does sound like he knows he's talking about. Oh well i don't know that was just my 2 cents.

 

[hdswanny]

that goes to show that the flywheel didn't cause any inconsistencies, it's the driver regardless of AWD or FWD.
its all a matter of adjusting how you drive.

i would like to see a consistent FWD driver with a lightened fly post. maybe they don't exist.

i know i couldn't drive a fwd, but like i said, it was because of FWD not a flywheel.

 

[boostineklipz]

I have a JUN lightweight flywheel...It takes some getting use to with launches, I found it to be a little bit more difficult to get a good launch, but I like how the car revs alot faster

 

[GRNDSM]

Guys,

I have wrote posts on this subject several times in the past. I have experimented with stock (21lbs), Jun (~9) and lightened stock (~15lbs).

Fist, I will start by saying that you should not use lightened stock FW. It is just not worth the risk of granating your engine... But I disliked Jun FW because it was way too inconsistent in 11.4 sec AWD.

For the record, I have been using stock FW on my 11.3 sec AWD Talon for the last 3 years and like it a lot!

I am going to have to pick up SFI approved FW for safety reasons and I do not really want to use Fidenza. It is just too light for optimum launching. No offence hdswanny, but consistent 1.81 60' times are consistanly bad 60' times... And that is not good enough for me.

I might sell my Fidenza FW (~9lbs) in favor of anther very slimilar FW which weights 16lbs.

 

[turboholic]

-Please be aware that lighten fly wheel is not the same as lighten OEM fly wheel. The lighten OEM fly wheel tend to crack easily, the Fidanza is aluminum+steel inseert=$400+. I think $ is better spend on lighter wheel, since I don't have neither, so I will shut up now.

 

[hdswanny]

hehe thats why i said i am a novice driver at best. And for me going from a FWD(2.3) to an AWD (1.81) thats good. I have only made it to the track 2 times this year since i have acquired my awd, with a total of about 6-7runs. I need alot of practice, but i also need a suspension.
excuses, excuses

 

[Tevenor]

Flywheels are another case of pick the item that matches your needs. A super light flywheel is most optimized in situations where there is a lot of reving through the power band on course such as Autocrossing and Road racing. In those cases there is no worries about launching the car since the greater gains is the accelerationg while moving (similar to speeding onthe street and after the launch in the 1/4).

For drags, its a different story. You want some momentum (mass) to help you get going. I think Leon (GRNDSM) Nis right on here. The benefits you gain from running a litter faster through the power band won't make up for the disadvantage a severly lightened flywheel will have at launch.

 

[STARION]

I think you may consider keeping the stock flywheel and having weight taken off the crank (like what FFWD does along with their knife edging) if you ever happened to build your bottom end. I believe it would have a similar effect as a lightweight flywheel would, no?

 

[KenTSIII]

But it would still have the same effect on the launch as the lightweight flywheel.

 

[Zerocygnal]

Again..this was with mustangs...

Lightening the flywheel DOES reduce engine rev time
Lightening the flywheel DOES cause a loss of torque by enerita weight

Usually the only thing you are going to want to do with a street driven/light drag racing vehicle is to at MOST knife-edge the crankshaft counter weights. Use a light underdrive pulley such as http://www.dsm-performance.com/catalog/product_info.php?products_id=115

As stated above the OEM Flywheel can be lightened however recall the statement of it being prone to cracking. The aluminum will desapate the heat better and a warm clutch is better for the launches in my experience so stick with the OEM as it is. Just resurface it!

Just my 2cents...

 

[NosLaser]

...i have a fidanza fly and i love it. The revs are quicker, resulting in faster spool up....

I want everyone who has ever made the above statement to read this post. For the last and final time, a lightened flywheel or aluminum flywheel will NOT make your turbo spool faster. If anything, it will make your turbo build boost and spool slower. Just because the rpm's are going up does not mean the turbo is spooling faster. Turbochargers are NOT rpm dependant, they are LOAD dependant. Rev your engine when it's not in gear. Go ahead!! Rev it up to 8 thousand rpm! How much boost did you build? Now, why on earth do you think the car builds boost when you are in gear? If it didn't hit boost at 4K rpm while free revving the motor, why is it hitting boost when you are in gear? The answer is LOAD. It has really nothing to do with rpm. If it had to do with rpm, then a 4 cylinder could spool a T-66 just as easily as it could spool a T25. A 4 cylinder doesn't create enough exhaust energy (read: LOAD) to spool that large turbo. If you are taking weight off the rotating assembly, you are decreasing the load, and therefore, slowing spool up time. Put your car on jackstands, and go through the gears. You won't build nearly as much boost as if you were driving the car normally. The revs may go up real fast, but fast revs does NOT equate to faster spool-up or more power. This is a very basic lesson that I feel a lot of people need to learn. The ADVANTAGE to an aluminum flywheel is from a safety standpoint. Aluminum doesnt shatter like cast iron. There's your advantage. In drag racing, they actually run weighted flywheels because the stored energy the flywheel has created when the rpm's are being held up is much greater than with a lighter flywheel. When the clutch is dropped, or the transbrake is released, all that energy shocks the driveline, and hits the tires that much harder causing the car to leap out of the hole. Sorry AWD guys, but you will NEVER experience that affect like a RWD car does. This is going to be a tough analogy to follow, but RWD cars GAIN out of the hole, while AWD cars simply leave just good enough to not be losing any time from the launch. Just some information I wanted to share to hopefully weed out the idea that a lightened flywheel will help spoolup.

Regards,

 

[95talontsi]

wait aren't turbo's load dependent, and a heavy turbo would place more load on the engine, cause auto place an constent load on the engine and a buddys grand national could just sit there and build up a lot of boost.

 

[NosLaser]

That is called power braking. Remember, your buddy and his GN are not doing that in neutral or park, he is doing that in drive. He is loading the engine up against the drivelien, and the brakes. He is still loading the turbo against something. He still won't build as much boost by power braking as he will by rolling along at 40mph and punching it though. With power braking, the power will eventually overcome the brakes and start to spin the tires. The car will lose some load through those spinning wheels, and it won't build any more boost.

Regards,

 

[95talontsi]

yeah I know that, but it's the same principal a heavy flywheel will help the turbo build boost quicker that's why the turbo makes more boost going up hills , or awd guys 1st gear is real steep and the turbo does make as much boost as in 3rd, am I right??

 

[NosLaser]

Exactly. That's the point I was making.

Regards,

 

[hdswanny]

wouldn't the reduction of rotating mass free up some ponies? or would it just reduce torque?

 

[whatturbo]

Another point people don't realize when thinking about lightened flywheels is that the same lack of weight that makes the engine rev free-er makes it rev down just as quickly. In my opinion, AWD cars would see the least benefit from a lightened FW because we can use the extra weight to help get our heavy driveline moving.

 

[NosLaser]

http://www.dsmtalk.com/forums/showthread.php?threadid=60276

! I was directed to this thread by email from someone. At least they referenced over here so they could find the real answer to their question instead of guessing. And dear Lord is 4G63Rydah a tool...

Regards,

 

[doug]

So, would the same argument apply for lightweight underdrive crank pulleys as applies for lightweight flywheels? Is a lightweight crank pulley not necessarily better than a heavier one? (Disregard for the moment the issue of dampened vs. undampened)

 

[NosLaser]

As far as the crank pulley goes, it won't be as much of a contributing factor to load, but it WILL be a contributing factor of getting weight off the rotating assembly. In a perfect world, you would want an ultra light, ultra strong rotating assembly, with a heavy flywheel that is shatter-proof. The function of the flywheel is to plain and simply, store energy (when talking from a power standpoint.) When you are sitting at the line (in a 5 speed car) and you are holding the revs at 5K rpm, waiting for the light to turn green, when you drop that clutch, that big heavy flywheel is basically 'throwing' all that energy you have built up at the transmission, and thus, eventually at the wheels, allowing the car to leap off the line. Basically, you take a trade off either way you go. I guess I would recommend a lightweight flywheel for a naturally aspirated car more so than a turbo car. But to answer your question, the lighter crank pulley will do more good by taking weight off the rotating assembly than it will do bad by eliminating a bit of load.

Regards,