Do you lose top end with a lighter flywheel?

[Race94]

Well i am getting the fidanza 8lbs flwheel installed on my 6-bolt, my car has pretty decent top end, 98mph constant in the 1/4 and i will be adding a AFPR to see if i can better that milleage, anyways i have been told that i will be losing top end because i have a lighter flywheel, is this true??

 

[MNGSX]

You would lose at the short end of the track... If at all...

You may actually gain at both depending how light + on tires.. driver etc.. You may not break loose as bad at launch...

The stored energy of flywheel mass really matters most at the line..

Farther out lighter=better...

[LOSE the second O in LOSE.]

It is supposed to be loose.. Not lose... As in break traction on his FWD car
[You had "loose" in the first sentence, too.]

Umm OOoops.

 

[hewhoisknot]

i heard u lose lower end

 

[Defiant]

You're removing mass that has to be accelerated. Effects, if any, will be a faster loss of revs between shifts -because there's less flywheel effect, imagine- and a quicker increase in revs for.... can you guess? Yes, the same answer.

How could it possibly cost anything on the top end? "Lose lower end" What, having to spin up that mass make for bigger engine muscles?

With all honesty, and in all seriousness, where do some of you get your ideas? Do they really seem to make sense to you?

http://www.geocities.com/MotorCity/7177/flywheel.html
http://www.geneberg.com/flywheels.htm
http://www.se-r.net/engine/light_flywheels.html
http://www.lunaticfringe.org/vwfox/mod/flywheel.html

 

[blackGSX2g]

^Agreed...the biggest factor you need to address regarding aftermarket lightweight flywheels is when you let off the gas, your engine will slow down alot quicker than the stock ECU accounts for. I've heard of cases where the car will sputter and almost die if you let it come down to idle after taking it to high RPMs. These issues can be ironed out most of the time.

If you think about it, how could taking a load off of the motor make it slower? Top end or bottom end? Less mass that needs to be turned = more power going to the wheels.

 

[99gst_racer]

I've heard of cases where the car will sputter and almost die if you let it come down to idle after taking it to high RPMs.

Yeah, my motor has stalled a few times from coming from high RPM to idle really fast with my 8.5lb Fidanza. I just raised the idle to compinsate.

 

[Jeff_Jeske]

So you guys actually take your foot off the gas to shift?

Kidding NLTS kicks @$$!

The aluminum flywheel also tends to overheat and warp easier than the heavy duty stock one.

 

[blackGSX2g]

So you guys actually take your foot off the gas to shift?

...bastard

The aluminum flywheel also tends to overheat and warp easier than the heavy duty stock one.

Yes, thats true too...I got the Chrome-moly ACT one that has a bit more meat to it. I didn't want to go too light, and since I had to buy a 6-bolt flywheel anyways, I figured I'd upgrade. There's a decent difference in going from stock 19lbs to 11.8lbs or whatever the ACT one is.

 

[99gst_racer]

So you guys actually take your foot off the gas to shift?

Kidding NLTS kicks @$$!

Yeah, I have NLTS and coupled with my alum flywheel, it does kick ass!! Shifting is incredibily quick and responsive.

 

[Race94]

Thanks for clearing things up, i was starting to have second toughts about putting it in, i usually brake the car if going fast or slow this way, after throttle i let gas go so the engine spins down a bit and then let go of the gear.

If it dies i'll raise the idle then.

Thanks!

 

[GSXRolla]

Another little interesting piece of info. Back when DSMTalk was around, and when I was looking for the same answer, I got a message back from Taboo over there. Supposedly, what they were finding out that the lighter flywheel was pulling a lot of bigger turbos out of the effective boost range because of the sudden rpm drop. They were pulling faster times with a stock flywheel because they were staying in the good boost range, instead of falling out of it.

When I say they were using bigger turbos, I mean bigger than a 20g. I'm rollin a small 16g, and I love my fidanza. However, knowing what I know now, if I moved up to a hybrid t3/t4 of some sort, I'd probably revert back to a stock flywheel.

 

[blackGSX2g]

Another little interesting piece of info. Back when DSMTalk was around, and when I was looking for the same answer, I got a message back from Taboo over there. Supposedly, what they were finding out that the lighter flywheel was pulling a lot of bigger turbos out of the effective boost range because of the sudden rpm drop. They were pulling faster times with a stock flywheel because they were staying in the good boost range, instead of falling out of it.

When I say they were using bigger turbos, I mean bigger than a 20g. I'm rollin a small 16g, and I love my fidanza. However, knowing what I know now, if I moved up to a hybrid t3/t4 of some sort, I'd probably revert back to a stock flywheel.

How light was the flywheel that they were using?

 

[MNGSX]

Yeah, my motor has stalled a few times from coming from high RPM to idle really fast with my 8.5lb Fidanza. I just raised the idle to compinsate.

I have'nt had a problem with my 4.75lb on ether the pro-efi or when it was MAFT alone... Now that I'm expecting to have a AEM on board before I pull the cover off the car and get it out of storage... I'm not worried either..

I really can't think of too many times when I actually have gone from high rpm to idle.. At the end of a high speed run I usually engine brake along with braking.. Just rev-match the downshifts and don't force anything...

 

[MNGSX]

So you guys actually take your foot off the gas to shift?

Kidding NLTS kicks @$$!

The aluminum flywheel also tends to overheat and warp easier than the heavy duty stock one.

What?

It disipates heat faster..

RRE Flywheel Tech..

A really light cromemoly is far more likely to turn into a POS...

Same with a lightened stock flywheel.. You have to turn it to resurface it.. So if you roach the surface and it is cut down on the backside from lightening .. You don't have much left to remove and making it too thin if you do..

I agree with the NLTS

Another little interesting piece of info. Back when DSMTalk was around, and when I was looking for the same answer, I got a message back from Taboo over there. Supposedly, what they were finding out that the lighter flywheel was pulling a lot of bigger turbos out of the effective boost range because of the sudden rpm drop. They were pulling faster times with a stock flywheel because they were staying in the good boost range, instead of falling out of it.

When I say they were using bigger turbos, I mean bigger than a 20g. I'm rollin a small 16g, and I love my fidanza. However, knowing what I know now, if I moved up to a hybrid t3/t4 of some sort, I'd probably revert back to a stock flywheel..

The only way it could be the flywheel weight is if the shift takes too long and the engine revs below the starting RPM of the higher gear. If you make a fast rev matched (engine RPM coast down to gear start RPM no lower) shift and it still drops bellow efficiency.. It is'nt the flywheel... It's the gearing...

Run NLTS and a light flywheel... You will take the load of the trans input shaft the fastest. Coats down quicker to the right rpm.. All while maintaining boost since the throttle stays open and it drops spark like a 2 step (stutter box) does at the line...

I run what I run for a reason... If I did'nt think the SSG was better constructed and of better material (different alloy) than a fidanza I would'nt have it.

 

[kristmen]

I have a question about your guys NLTS mods. What RPM do you guys have that set at?

 

[suicidal2af]

You're removing mass that has to be accelerated. Effects, if any, will be a faster loss of revs between shifts -because there's less flywheel effect, imagine- and a quicker increase in revs for.... can you guess? Yes, the same answer.

How could it possibly cost anything on the top end? "Lose lower end" What, having to spin up that mass make for bigger engine muscles?

With all honesty, and in all seriousness, where do some of you get your ideas? Do they really seem to make sense to you?

http://www.geocities.com/MotorCity/7177/flywheel.html
http://www.geneberg.com/flywheels.htm
http://www.se-r.net/engine/light_flywheels.html
http://www.lunaticfringe.org/vwfox/mod/flywheel.html

This is actually a commonly spread misnomer that's been around since the musclecar days. People (wrongfully) assume that since torque is a derivative of rotating mass(crank/piston), that having a lighter flywheel will produce less torque...less rotating mass after all, right?

Except it doesn't really work like that. Flywheels don't produce power. Lighter flywheel makes it easier for the engine to turn it, which means less parasitic loss. Which means more torque transferred to the wheels.

It does, however, diminish the amount of energy stored by the flywheel, so it's going to slow down a lot faster between shifts. Solution? Learn how to shift faster

 

[Jeff_Jeske]

It does disapate heat faster but it doesn't have as much mass so it overheats faster as well as sheds heat faster. But the stock one can take more abuse before having issues.

I have my NLTS set at 5500 RPM.

 

[guitarXgeek]

I use 5500 for NLTS, but only because I'm still on the t25 :thumbdown . If I had a turbo that would actually make any power over 6000, then I'd have NLTS set at 6000 - that seems to be the magic number . Oh and I believe DSMlink cuts fuel for the stutter box and NLTS, not timing

 

[Ian M]

I havent seen any difference in driveablity going to a lighter flywheel. The only real difference I could feel was a bit more throttle response in nuetral.

The main reason I switched from my stocker to a ACT chromemoly was for safety.

I have seen too many videos and horror storys of exploding flywheels. Its a small price to pay to avoid destroying a tranny and engine,and in the process driving through the coolant and oil at 100+ mph and possibly crashing the car. Or maybe have a chunk of flywheel come through the floor and remove you or your passengers foot.

Over the past few years with all the big turbos and components availible,higher performance cars with a lot more HP and RPMs have been easier to build,and you will see more instances of flywheels coming apart. Trusting a 13+ year old flywheel that has been heated and cooled a million times at 8000 RPM 'aint me...

The RPMs dropping might not be all bad..It would seem a lighter flywheel would be easier on syncros too,particularly for the guys with smaller more responsive turbos.

Also,the Fidenza and ACT are SFI approved,which is required to go 11.49 (as of the 2005 season,was 11.99) or quicker.

 

[4ged4G63]

............

 

[MNGSX]

It does disapate heat faster but it doesn't have as much mass so it overheats faster as well as sheds heat faster. But the stock one can take more abuse before having issues.

I have my NLTS set at 5500 RPM.

That somehow does'nt explain why a stock flywheel can be seen bouncing behind a car making a run after exiting the bell housing and engine bay the hard way.... Anybody see an SFI flywheel do that? The video is still up on the net... Or the stock fly sticking out of the hood of a car... etc...

The same physical size flywheel from AL vs CI will have different masses due to the molecular weight differences... However, the surface area is the same and the heat transfer of aluminum if faster... So the AL runs alot cooler all things being equal..