Anyone run an Aluminum flywheel?

[alkemyst]

Not looking for bench racer's commenting...I have read about them. I am looking for those that have used them.

I am looking at the Fidanza for my 240SX (KA24DE)...stock is about 26lbs the Fidanza is 11lbs. There is a company that machines stock units to 16lbs but that is the same price of the Fidanza.

I shift quickly already, I don't do the granny 1 second between clutch and shift at all. Pretty spirited driving only...when I am transporting people I use my wife's car.

Thanks
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[JulesMaximus]

Fuck, I thought you were talking about a crankshaft pulley...I do know what a flywheel is, it just didn't click when I read it this morning and responded.

My bad.

 

[NutBucket]

It won't help you shift quicker, it'll just help the engine rev faster. As a side effect, you will drop RPM faster when shifting so you'll have to compensate accordingly.

Hell, I noticed a minor difference from a lighter crank pulley. I definitely plan on a lighter flywheel when the time comes.

 

[alkemyst]

The main reason I am doing this is because if I source a flywheel at the time I am doing my clutch it's a one day job. A new flywheel (remanufactured) is about $100. For another hundred or so I can do the aluminum.

The labor is a wash, so I am not just adding this as it's own deal.

I just don't want issues.

 

[Demo24]

You'll need to be careful with this. A lighter flywheel can cause these two main issues:

a)Because the engine is spinning up/down at a different rate than it expects you can often throw codes or have other serious problems.

b)It will be easier to stall the engine with less rotating mass. That may not be a concern for you, but could be annoying. One reason many high performance cars can be difficult to drive.

Best to do some research on a 240 board to see how it will affect your car.

 

[jlee]

I had one years ago - I really liked it. It was 9lb (stock was..ugh I can't remember, 13 or 16?). It's definitely easier to stall, but if you know how to drive you'll be fine.

The engine will be very rev-happy. I'd like to get one for my 2 but I'm not interested in pulling a perfectly functioning drivetrain apart to install one.

Keep in mind with less inertia you'll have less 'punch' when you let the clutch out - i.e. if you're chirping gears when you shift, that may be lessened due to significantly less mass getting latched onto by the clutch. It will be easier to stall, but if it's anything like mine was, it'll be very streetable.

I've never heard of an engine throwing codes because it revs too fast...not saying it can't happen, but I haven't heard of it.

 

[lurk3r]

The engine will spin faster both up and down. Less mass to accelerate will result in a faster response. It will also make it a much harsher ride, one of the main purposes of the flywheel is to smooth out the uneven nature of our engines. Some engines like the 400 chevs need large flywheels and harmonic balancers or they'll shake themselves to pieces.

Cutting the weight of a fairly heavy flywheel in half may be a bit extreme, but if its for 'sport' use only It'll certainly help your times.

 

[BlackTigers]

I have a Fiddy.

My ass dyno definitely feels the difference. The clutch needs to be slipped a little bit more on take-offs, but that's about the only negative I've felt.

 

[Demo24]

I've never heard of an engine throwing codes because it revs too fast...not saying it can't happen, but I haven't heard of it.

Might be more of a Subaru thing then. I know you generally don't mess with flywheel weight in them unless you get tuned for it.

 

[alkemyst]

Might be more of a Subaru thing then. I know you generally don't mess with flywheel weight in them unless you get tuned for it.

AWD computers could be sensitive to it...

 

[NutBucket]

Its not specific to Subaru. Knock sensors can be fooled into detecting non-existant misfires.

 

[Demo24]

AWD computers could be sensitive to it...

Nothing to do with that, the system is all mechanical so computers have nothing to do with the system. It has to do with knock sensor as mention above. I just couldn't remember exactly what was the issue until he posted that.

 

[alkemyst]

how does a flywheel cause knock sounds?

 

[NutBucket]

If the engine revs up/down more quickly it can cause vibrations that are were not present before. Knock sensor interprets it as detonation. It happens....

 

[Brian Stirling]

Reducing the rotating mass or more accurately moment of inertia will, among other pluses and minuses, give you more torque/power to the drive wheels when you are accelerating because the engine will need less to accelerate the flywheel.


Brian

 

[Hyperlite]

Reducing the rotating mass or more accurately moment of inertia will, among other pluses and minuses, give you more torque/power to the drive wheels when you are accelerating because the engine will need less to accelerate the flywheel.


Brian

but there is no alteration in mechanical drivetrain loss, so peak power/tq won't change. objects in motion/objects at rest....

It's similar to installing lightened main crank/pulleys. You aren't going to see a quantifiable power boost, but it'll rev faster.

 

[Demon-Xanth]

I would say that the flywheel prevents the false-knocking and the ECU is tuned as such. Going to a lighter flywheel removes the prevention. If you look at it that way, it makes more sense.

 

[alkemyst]

but there is no alteration in mechanical drivetrain loss, so peak power/tq won't change. objects in motion/objects at rest....

It's similar to installing lightened main crank/pulleys. You aren't going to see a quantifiable power boost, but it'll rev faster.

Power can change from reciprocating mass being removed.

 

[Pantlegz]

I highly doubt you'd see any (significant) power gains but as others have said it'll be more rev happy which with the KA would be nice. I think it would be a worthwhile investment.

oh and phase2motortrend has some decent one piece aluminum drive shafts while you're at it. less rotating mass = good

 

[Apex]

I have lightweight flywheels in two of my current cars, one is a fidanza. Nice units. I like the difference in feel. Makes launching a bit more tricky though.

 

[alfa147x]

God do I miss my KA24DE!

 

[EightySix Four]

Lol, my flywheel weighs 55lbs. I shit you not, 55lbs on an I4. It's also dual mass, gets out of balance, and explodes at 9k rpm.

 

[exdeath]

No power gains, just faster revving. Easier to bog off the line though.

Shift speed isn't much of an issue, it's more a function of your dashpot (return to idle curve) when you lift. My stock Toyota 4 banger with a steel flywheel drops to idle in less than a second in almost a straight vertical drop when you press in the clutch. The Cobra with the lighter aluminum flywheel floats down gracefully and gradually with a progressively slower curve.

The engine accelerates quicker when power is applied due to less inertia, and it can also decelerate quicker when power is removed. "An object in motion stays in motion...", yada, yada. Key is "when power is applied/removed", an aluminum flywheel won't cause faster idle drop and penalize slow shifting unless the engine is accelerating/decelerating. In other words RPM falloff has nothing to do with the flywheel weight but your idle return programming, which if stock, is more than likely determined by the original transmission gear ratio spacing. ie: a car that came with a close ratio gear box is going to be programmed from the factory with a slower idle drop, car with wider spread gears is going to have a faster idle drop; point is to have the RPM falloff on throttle lift to line up right with an average upshift. Nothing a retune can't adjust to your liking.

Cobra already comes stock with an aluminum flywheel so no real benefit; I replaced it with Fidanza with a replaceable friction ring because some of the rivets broke on the non serviceable stocker, and for the same reason you're considering it: to do it all in one go. And I got a packaged deal on a matched and balanced assembly.

If a flywheel causes knocking sounds, you installed it wrong.

If you're really picky and want to do it right, take your new clutch and flywheel to a machine shop with a $50; the flywheel should be balanced with the clutch you are using. Aluminum will be more susceptible to vibrations if something is slightly off balance and you'll feel it in the pedal and the shifter (if it's a direct linkage).