Billet or Aluminum Flywheel?

coolblue65 · Mar 30, 2007

As I am currently planning a new motor (347), I am trying to make some final decisions on parts.

I have been looing at flywheels and it looks like a Ford Racing Billet Steel flywheel is around $245 shipped and SFI approved, and a Fidanza aluminum is $283 shipped but not SFI approved. Because they are close so price won't play to much in the decision.

The aluminum only weighs 13.5lbs and the billet weighs around 25lbs, obviously that is a big difference. However I am not sure how this will affect my day to day driving, HP, etc. etc.

Is anyone running an aluminum flywheel now or has any experience with them? I have heard a lot of mixed reviews and need some help deciding.

Thanx!

65ShelbyClone · Mar 30, 2007

The Fidanza aluminum should be SFI approved........that's what I have and it's SFI approved.

My Fidanza is no problem on the street with 3.50 gears and a 302 in a '68 Mustang. Seriously, it's not a drag car or anything, yet it's pretty easy to drive stoplight to stoplight.

EDIT: I forgot to mention that I also have a single plane intake and a 650. Both of those hurt the bottom end slightly, but my Crane is a high lift/low duration smog/blower cam that compensates somewhat. The engine usd to be in a 3300lb '89 GT with an iron flywheel and 2.73 gears and that wasn't hard to drive either. People with small gutless engines are going to see the biggest degradation in slow takeoffs. V8s have much larger and heavier rotating assemblies not to mention more low-end toque, so aluminum flywheels will hurt much less........IMO

RUSTYNUT · Mar 31, 2007

Steel is going to be better for an driver. Light flywheels are great for a moving car to accelerate faster. A few of my friends driving imports have had problems with the disimilar metals warping the fly wheel. They do drive the @#$% out of them.

ratio411 · Mar 31, 2007

A heavier flywheel tends to use weight to multiply torque, in effect.
A lighter flywheel revs much faster, but will lose low end torque.
Pretty much because it has less mass to 'bully' the rest of the driveline with.
I have heard folks complain about the really light flywheels being too touchy with throttle response. I can't imagine that myself...

I forgot to mention that I also have a single plane intake and a 650. Both of those hurt the bottom end slightly, but my Crane is a high lift/low duration smog/blower cam that compensates somewhat.

Are you making the point that even with a single plane intake, you have no trouble street driving?
Or
Are you saying that the lighter flywheel would perform better with a torque friendly intake?

Just curious.

When you rev the engine in P or N, snap the throttle, does the engine come back to idle more quickly or less quickly than before?

I have always wondered that.
I would imagine that less rotating mass would bring it back to idle rpm much faster than a mass that tends to keep spinning because of centrifigal force.

Dave

65ShelbyClone · Mar 31, 2007

ratio411 said:
1.) Are you making the point that even with a single plane intake, you have no trouble street driving?
2.)Or Are you saying that the lighter flywheel would perform better with a torque friendly intake?

Just curious.

3.) When you rev the engine in P or N, snap the throttle, does the engine come back to idle more quickly or less quickly than before?

I have always wondered that.
I would imagine that less rotating mass would bring it back to idle rpm much faster than a mass that tends to keep spinning because of centrifigal force.

Dave

1.) Yes
2.) Somewhat. The intake is just part of the bigger picture.
3.) Quicker up and down.

My point was that the more low-end torque you already have, the less difference an aluminum flywheel will make in street manners. Rear gears help a lot too. I wouldn't recommend one for a stock or heavily cammed engine with 3.00s.

ratio411 · Mar 31, 2007

65ShelbyClone said:
1.) Yes
2.) Somewhat. The intake is just part of the bigger picture.
3.) Quicker up and down.

My point was that the more low-end torque you already have, the less difference an aluminum flywheel will make in street manners. Rear gears help a lot too. I wouldn't recommend one for a stock or heavily cammed engine with 3.00s.

Gotcha.
Makes sense.

I never considered the rear gears.
Should have though. If there is less mass to influence the driveline, then the driveline should have more lever (gear).

I have been considering aluminum flywheel for a while.
I ended up with a steel Hays unit only because I got a great deal on a 'new' one in the box.
I will get around to aluminum one day.

CraigMBA · Mar 31, 2007

Anybody ever seen a CART or IRL car leave the pits?

Notice they always do a burnout every time they drive out of the pitbox?

They don't do it because it's cool, they do it because they have to. The engeneers have removed all the rotating mass from the engine and if they slip the clutch out, the engine will stall.

I'm going to build a 331 here soon, and I'm going with a neutral balance ( 0 oz ) steel flywheel. Occasional street driving, mostly OT.

fasttback · Mar 31, 2007

I was thinking the same during my 352 (4.06x3.4 stroke) build. I went with a Aluminum Ram 164 tooth flywheel (weight about 15 pounds) in my '66 fastback. As I recall some comments were - it is suited more for a drag motor, and if you run it on the street you will need a high torque motor to offset the lost weight (inertia) of a steel one otherwise it might stumble off the line.

I love it. No problems off the line and shifting. Behind it I have a Toploader, Hays street/strip clutch, and a 9" with 3.50 gears.

ratio411 · Mar 31, 2007

CraigMBA said:
The engeneers have removed all the rotating mass from the engine...

Probably have titainium and kevlar for internal parts, engine and tranny. And a true lightweight flywheel is more like 6-12 lbs, not middle weight like 15-16 lbs.
I am not sure that a 15# aluminum flywheel constitutes that kind of weight reduction.

coolblue65 · Mar 31, 2007

Lots of good info so far.

65ShelbyClone - As far as Fidanza being SFI approved, Summit's website's says its not approved and I can't find anything on their website saying if it is or is not.

I think I will end up going with the Aluminum, I think the 347 should have plenty of torque down low (especially compared to my current 289 setup) to compensate for the less rotating mass.

rbohm · Mar 31, 2007

one more thing to consider for a street engine, besides rotating mass, is durability. the steel wheel will be more durable and thus more suitable for a street engine than the aluminum wheel will. if you do go with the aluminum wheel, make sure that it has a bronze or steel friction surface that is removable for when you go to replace the clutch. at 15lbs you wont notice a problem with launching the car on the street, as long as you have a 3.25 or lower gear(3.50-3.90 is ideal for the street with an overdrive).

badmustang · Mar 31, 2007

check this noise light flywheel

http://www.youtube.com/watch?v=9tbtTsbS_cQ&mode=related&search=

badmustang · Mar 31, 2007

noise of a heavy flywheel

http://www.youtube.com/watch?v=KbTdpxQLxUs&NR=1

coolblue65 · Mar 31, 2007

rbohm said:
one more thing to consider for a street engine, besides rotating mass, is durability. the steel wheel will be more durable and thus more suitable for a street engine than the aluminum wheel will. if you do go with the aluminum wheel, make sure that it has a bronze or steel friction surface that is removable for when you go to replace the clutch. at 15lbs you wont notice a problem with launching the car on the street, as long as you have a 3.25 or lower gear(3.50-3.90 is ideal for the street with an overdrive).

I have thought about that, the Fidanza has a replacable/servicable steel friction surface.

As far as gearing I have 3.55's in back, and the first gear in my Tremec is a 3.27 so I think I have enough there.

Badmustang- I am not sure what I was listening for on those clips- two different cars with different motors and exhausts is what I saw/heard.

ratio411 · Mar 31, 2007

I think he was trying to illustrate the speed at which the rpms respond to throttle snaps on a steel wheel vs aluminum wheel.
The yellow Stang revs up and down much quicker than the long drawn out revs of the white one.

badmustang · Mar 31, 2007

ratio411 said:
I think he was trying to illustrate the speed at which the rpms respond to throttle snaps on a steel wheel vs aluminum wheel.
The yellow Stang revs up and down much quicker than the long drawn out revs of the white one.

that's correct the yellow stang rev faster up and down light fywheel
and the other stang has a heavy flywheel..
i also had a heavy flywheel in my stang an have now a centerforce aluminium flywheel and i like the centerforce the soud of the engine i verry nice.
and it feels that the car lost 100 pound of weight after is change the flywheel

light flywheel is better for the enginge bearings

65ShelbyClone · Mar 31, 2007

coolblue65 said:
65ShelbyClone - As far as Fidanza being SFI approved, Summit's website's says its not approved and I can't find anything on their website saying if it is or is not.

Go to Fidanza's catalog download page here. Dowload the catalog and you'll see that their flywheels and flexplates have the SFI seal. Mine does:

ratio411 said:
Probably have titainium and kevlar for internal parts, engine and tranny. And a true lightweight flywheel is more like 6-12 lbs, not middle weight like 15-16 lbs.
I am not sure that a 15# aluminum flywheel constitutes that kind of weight reduction.

The CART engine analogy was more of an extreme example. The CART engines use steel cranks, proably titanium rods, and forged aluminum pistons. However, the "flywheel" isn't so much a flywheel as it something to bolt the 5-8" clutch onto. They also have a very short stroke coupled with big cylinder heads for lots of top-end power at the expense of a non-existent low-end. The clutches also bite like a mofo, so easy takeoffs would be hard anyway.

And yeah, a 15lb flywheel is lighter than the stock 25lb cast iron lump.

coolblue65 · Mar 31, 2007

65ShelbyClone said:
Go to Fidanza's catalog download page here. Dowload the catalog and you'll see that their flywheels and flexplates have the SFI seal. Mine does:

Thanks, thats what I needed to see. They don't really make it obvious though!

fasttback · Mar 31, 2007

65ShelbyClone said:
And yeah, a 15lb flywheel is lighter than the stock 25lb cast iron lump.

Agreed. - and it sure cut down on some weight from my Hays 33lb SFI steel one I use to have.

65ShelbyClone · Mar 31, 2007

coolblue65 said:
Thanks, thats what I needed to see. They don't really make it obvious though!

You'd think they would be eager to advertise SFI approval since it is an important selling point to some people.

Billet or Aluminum Flywheel?

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