which flywheel?

If I had the money I'd go aluminum for the weight savings. Is the car a daily driver? I'd probably go billet steel for a daily driver.

If I had your car I would spare no expense on a nice flywheel. Fidanza makes a nice lightweight model for around $350-400. SFI and everything. Might be something to look into.

1991vert said:

this car will be driven on the street. im not skimping on money, i just want to know which one would be better. am i gonna go through clutches slipping the crap out of the aluminum one?

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Fidanza aluminum No you won't go through clutches. Love mine. Lighter the better. I got mine through Rick 91GT (my engine builder) He wouldnt sell me something bad

Weight savings for faster rev's and less wear and tear/stress on your crankshaft. Its less weight that your crank has to spin. No brainer.

Let me know if you need more experienced help.

The clutch face is actually steel (on the aluminum flywheel) so there is no need to worry about tearing up the clutches or the face of the flywheel. I think the Fidanza Aluminum wheel only weighs 13.5lbs.

The thing about steel is that it carries a lot of inertia. So in constant speed situations there is an advantage for steel. But when it's time to change speed (accelerate) you use more HP to "spin" the steel. I wonder if there is a MPG penalty for this?

If it were my money (it's easy spend someone elses) I would get the aluminum one also. In fact, if I ever get around to doing my clutch this year I will be switching to aluminum

I just used a billet steel with my centerforce only because centerforce suggests a billet steel for their clutches.

Real quick, just like most...if your not going to drive this as a daily driver...I'd personally go aluminum. And your right, skimping doesn't mean buying something cheaper, it is about buying the "right" (opinion) part.

Here ya go...I personally like billet steel. Here are some opinions on them vs. aluminum:

Here is some interesting info from another board, right from Centerforce themselves.

Originally Posted by Will Baty
Another thing to think about is that in most cases the steel flyhweel has more heat sink. This typically means longer clutch life, seeing how heat is a big killer for clutches. The steel flywheel has more mass which allows it to absorb and dissipate the heat that is generated from the clutch when the car is put into motion. Both flywheels do have pros & cons, you should look at what some of the other guys with similar or the same set-up as what you have are using. Another thing to look at is what percentage of your driving is around town daily driving? Do you want every ounce of performance out of your car or are will to sacrifice a little performance for more drivable clutch around town? I not saying that the Aluminum flywheel is bad by any means I know allot of guys with the Aluminum flywheel that have no problems what so ever. I am just saying that steel vs aluminum on the street 9 times out of 10 the steel will have the better clutch feel.

Just my 2 cents.

Will Baty
Centerforce Clutches

Let me copy a couple post from other discussion on this:

"I'm a billet steel fan...

The aluminum flywheel will help you decelerate quicker and accelerate a tick quicker if you want that little extra addition but some things to think about with the AFW is starting from a stop, particularly on hills, may require more slipping of the clutch to make up for the lower momentum than is stored in the heavier stock flywheel. Some jerking can be occured due to the loss of momentum possibly in between shifts for example as the rpm will drop sooner.

I would stay away from an aluminum flywheel on a daily driver and plus some of the harder grabbing clutches can tear up the aluminum flywheels...and aren't recommended with a aluminum flywheel. Inserts for the AFW flywheels cost more than a "steel" resurface...

Get a stock replacement or a nice billet steel one...(more expensive)...

This is posted from FastDriver - The answer to your question is that a 15 lbs weight would be easier to catch/stop if it has been thrown at you at the same speed as a 40 lb weight. A pretty obvious answer, but I think you are misinterpretting the results. A drag racing launch has nothing to do with ease of launch. If it did, you wouldn't launch at 6500 rpm, you'd launch right off of idle. Also, my clutch doesn't seem to have any problems grabbing my flywheel at any rpm. My tranny doesn't seem to have any problem managing the shock, and with the right tires and suspension, I will launch this car right off of redline with a single clutch drop.

The point is that you want as much stored energy to jump into your tires as possible, and you want your suspension/weight distribution/ tire combination set up so that it can handle all of the power and effectively put it to the ground - as opposed to wasting it by blowing away the tires.

In regard to your posit about stored energy being meaningless, I'll counter that stored evergy has everything to do with the difference between a heavy flywheel and a light one. In fact, stored energy is the only cause of a performance difference between an aluminum and iron flywheel.

The aluminum flywheel does not store as much energy as rpms increase which gives it an advantage in that the energy that would be stored in the flywheel has instead been exerted into the rotational force in the drivetrain and hence the driving force/power of your car.

In drag racing, that extra stored energy in the flywheel at a stop is put into your tires as soon as the clutch is dropped causing more force/power driving your car as it leaves the line. As your car moves down the track and rpms increase, the energy is transferred back and forth from the flywheel to the tires as rpms increase and then decrease (as you shift). Finally, when you cross the traps, rpms at the top of their powerband, the stored energy in the flywheel did not get put to good use. So, the advantage after you leave the line is to the lighter aluminum flywheel. Does it make up for the Iron one? Possibly. The longer the track, the more likely. However, will the difference be significant enough to justify the extra expenditure? Not to me."

"we lost like .20 on our 60 foot times with an alum flywheel. its the initial shock the torque ripping the tires is what was different and in turn they say about every .10 in the 60 foot is about .15 tenths in the quarter. i find this to be a close fact went from 11.50-11.55 to 11.68-11.71 in the quarter i dont remember mph."

"I have dyno tested several different flywheel and clutch combinations. I was part of the article for MM&FF that Robin mentioned over on HC50. If you can find that, theres alot of good info in there. Since then I have done some prototype testing for another clutch manufacturer. Believe me when I tell you, 9lbs will not make a difference on a chassis dyno doing high gear back to back pulls. If you averaged 5 or 6 pulls, making sure that engine temp, trans fluid temp, rearend oil temp, air intake temps, etc.. were the same, I'd suspect you might see 1 horsepower. Thats doing high gear pulls only. There are other ways of making pulls that will show a greater increase, and give more real world results."

"I beleive it was Eagle on here (the one that sells the rotating assemblies - Brian?) that said the AFW does react differently under normal conditions. He seems like a pretty credible source on it as well seeing how he does sell the rotating assemblies Ed Curtis and some others (can't remember) where suggesting keeping a steel flywheel in the heavier side of the cars (like 3200lbs and up)...so that is where my lx falls into.

For autocross cars, I agree...your up in the revs for 99% of the time (almost literally) and your not building up speed (revs) if your autocrossing right so the AFW would be beneficial in that case.

For the picky daily driver like me...I'm not for the AFW."


Just a couple...it isn't just "losing weight"...you lose other things as well. Driveability changes. revs drop quicker so your engine will "catch" more in between time when you shift gears...you don't have the rotational weight to help you "idle off"...

I would keep an AFW for a autocross car...not really a daily driver IMO.

Now let me say I run the stock "$99" dollar flywheel from summit and have no problems with it. Looked just like the stocker it replaced and feels the same.

I have been told that the lighter flywheel will not dampen the uneven pulsations from the crankshaft as well. This is probably more of an issue the fewer the number of cylinders.

It is amazing to see people who think that getting an aluminum flywheel is gonna make you accelerate faster.....

Think of it this way, it may save a few pounds off the weight of your car, and off the weight of you drivetrain, but the only way a lightweight flywheel will affect your performance is when the clutch isn't fully engaged... like when taking off (more chance of stalling because aluminum FW carries less inertia and won't recooperate the engine) or when just revving your engine

when the clutch IS fully engaged, the engine, FW, is all directly hooked up to your driveshaft, differential, axles, wheels, tires, and in turn, the entire weight of your car. just because you put one little piece lighter weight, its still pushing your entire car, and isn't going to make you accelerate faster by any practical measurable amount.

It is acting just as an aluminum driveshaft would. Sure it revs up quicker when your in neutral, but not moving...


Good Luck!

1991vert said:

i bought the fidanza aluminum one and i bought a Fluidampr balancer. that was like $600 right there at least

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I got your PM. Hit me up later today.

Good choice on the fidanza aluminum. I'd pass on the fluidamper and go with a light weight Romac. I got my romac from Ed Curtis.

Nice post 5Spd... I can't count the number of times I've tried to explain that very thing only to loose my choo-choo of thought half way through. I'll have to copy that for future pasting.

Aluminum is a good option if you're running a car where every lb of weight matters. Otherwise, the deficiencies outweigh the advantages.

This would have been a hard choice for me, your car is most liket heacy so I woudl ahve went steel, but with the power adder I would have been more likely to lean towards the alum, it does have some benifits at the track and on the street by stealing a little inertia on the low end.

My question is are you building a internal balance "0" motor, atleast that what you posted, that link was a 50oz balancer. Make sure you buy the correct balancer, I also like the Romac Alum outer ring like Mike has. I also use a lot of the steel SFI Pioneers with great success, much cheaper$$$ as well. I prefer the Elastomer balancers over the Fluid filled units unless it is a Innovators West piece, hell SCAT won't warranty a crank that was done with a fluid filled...check out their site for more info. www.scatcrankshafts.com

And I might add, I'm not to sure on how an aluminum flywheel can add less stress on the crank unless it is parked And most of the time it is in gear so it is supported by being engaged and locked with the rest of the drivetrain.

With centrifugal force at idle (750+rpm) the flywheel is spinning so fast that all force is applied outwards and stress is taken off the central area of the crank. It is spinning fast enough where 8-10lbs isn't going to hurt the life of the bearings IMO.

Sure your car will rev up in neutral faster, nice to impress the friends, but once your drivetrain is locked (going down the road) it acts just like an aluminum driveshaft. I didn't notice anything from my aluminum driveshaft, hint hint...