Flywheels: Stock VS Lightened

[Billy.]

my LS/VTEC/Turbo motor is under construction as we speak. b18b block with fresh bearings and rings under a b16a2 head, matted to the b16 tranny. CURRENTLY the tranny has an exedy organic clutch with an exedy lightened flywheel, but the clutch is getting changed out to a stage 3 type unit. but here is the question: is it better to run with the lightened flywheel or with the stock flywheel?? reason i ask is that ive read very detailed writeups that recommend using the stock fly for boosted applications. ill quote a paragraph from Bees and Goats Web Productions:

there is a lot of controversy over lightened fly wheels in a turbo application. some believe that since a turbocharged engine moves through the lower gears so fast, adding a lightened fly wheel would make it move through those gears even faster, making it even more difficult to maintain traction than it already is in a front wheel drive turbo car. others want to get to higher revs as quickly as possible to make use of turbochargers that provide power at high RPMs. for street drivability, this author recommends the stock fly wheel. if you do chose to go with a lightened fly wheel do not get the lightest one possible. most lightened fly wheels are designed with naturally aspirated, high revving (low power compared to what a turbo Honda puts out) applications in mind. with all the added power being put through the fly wheel from the turbo a lightened fly wheel is more likely to fail the lighter it is.​

ok, so what's YOUR opinion? my car is going to be 98% daily driver, 1% autoX, and 1% dickin around on the long country roads near my house

 

[Scorchsta]

I would say go with the stock flywheel. You'll get better gas mileage cruising on the highway.

 

[Billy.]

explain?

 

[meekseer]

While I can't confirm or deny any noticeable gas mileage difference between the two, basically what you need to be looking at is the level of responsiveness that you want out of your pedal.

By definition: "A flywheel is a rotating disk used as a storage device for kinetic energy. Flywheels resist changes in their rotational speed, which helps steady the rotation of the shaft when a fluctuating torque is exerted on it by its power source such as a piston-based (reciprocating) engine, or when the load placed on it is intermittent..."

The key phrase in that is "Flywheels resist changes in their rotational speed". Meaning that the stock flywheel is going to be less responsive when you hit the gas, but maintain its inertia better when you're off or maintaining throttle. The lighter you go on the flywheel, the more response you're going to have when you push the pedal, but also the faster you're going to lose it when you come off the pedal. For that 1% autocross application you're looking at, the lightened flywheel should be a nice benefit for you, but will cause you to have to use a little more care during any stop and go portion of the other 98% daily you spoke of.

If I were having to make the decision, I'd be looking at where in my rpm band I was leaving vacuum on the turbo and how quickly I need to get there. If it's up in the RPM band (anything over 4K) and I regularly needed to go from ~1-2K up to turbo spooling, then the lightened flywheel is what I would choose. If the turbo is tuned for lower-end torque and is starting its spool by 3K, or I really didn't need to make use of boost as often, I'd choose the stock for a little more forgiveness from my engine during stop-and-go.

 

[SiRcivic27]

I went with a street light flywheel from ACT when I turboed my car because its going to become a weekend fun car and track car starting next summer. I dont have any problems with my car and it drives very nicely even in stop and go traffic.

 

[Billy.]

so you think the exedy street flywheel will be good with a t3/t04 57 trim setup?

 

[ryanM]

I went with a street light flywheel from ACT when I turboed my car because its going to become a weekend fun car and track car starting next summer. I dont have any problems with my car and it drives very nicely even in stop and go traffic.

light flywheels are pointless on turbo cars.

 

[jason_guy_yeah]

x2, you'll lose momemtum too quickly. Which means you'll have to shift real quick every time because, your engine rpms will drop quickly between shifts.

 

[SiRcivic27]

x2, you'll lose momemtum too quickly. Which means you'll have to shift real quick every time because, your engine rpms will drop quickly between shifts.

Maybe if you're racing at which point you're shifting quickly anyways... I get 34MPG with my car, its a great daily driver, and a blast to drive.

 

[mike@synapse]

light flywheels are pointless on turbo cars.

at least someone has given some good insight.

if you have a good oem flywheel, resurface it and throw it back in.

 

[ElantraTuner]

The problems with a lightened flywheel like stated is it loses momentum faster. This is most noticed when launching or starting the car because it will be nessecary to feather the clutch out/give it more gas than before since it won't hold its momentum.

With that said, I have a lightened flywheel (lightened by 6 lbs) and i love it. The car responses faster and it makes rev matching the car when downshifting easier/more fun. I daily drive my car and enjoy the 6 puck clutch/lightened flywheel combo that I so i'd go for it. The material that the flywheel is made of also helps. If the material is alumium/ chrome moly then its better because it disspates heat better.

 

[Billy.]

if it's not completely necessary to put the stock fly back in than im not going to. if rapid rpm drops are the only "problem" than its not a problem at all. i am a very experienced driver, blipped downshifting and heal-toe shifting are my daily driving styles. if using a stock fly sacrifices performance for a little extra daily driveability than it's not worth it in my eyes

 

[waderick]

at least someone has given some good insight.

if you have a good oem flywheel, resurface it and throw it back in.

good point and also by resurfacing it it will make it slightly lighter but not really noticeable and still has the momentom so you don't have to try and shift like your racing every time

 

[slowcivic E G]

i agree with what mike@synapse said, just get your stock one resurfaced and use that, save some money and dont worry about your rpms, im sure they will fly up plenty fast with your setup.

 

[Billy.]

i agree with what mike@synapse said, just get your stock one resurfaced and use that, save some money and dont worry about your rpms, im sure they will fly up plenty fast with your setup.

but ive already got the exedy flywheel from my last motor. i wont be saving any money by using the stock one, in fact paying to get it resurfaced is going to add to my already over-budget project