How much of an advantage is an aluminum flywheel?

[formula]

Pretty much the topic title. Is it worth nearly twice the price to pick up a 12 inch aluminum one that only weighs 13 pounds, when a comparable steel one weighs 30 pounds at half the cash?

[speedster]

Based on your PT garage, you should go with the steel. A flywheel's purpose is to store energy. A heavier one is used for street cars to make them smoother while driving around. If you were racing and wanted to have the rotating mass as low as possible for acceleration, then go with the aluminum. Don't waste your extra cash unless the rest of the car can take advantage of it. Just my .02 cents.
Nice Bird.

[chicane67]

Depends on application.

If you are utilizing it for its lighter inertia, then yes. Meaning, in a road race/autox application the lesser inertia will help with 'coming' off a corner and accelerating out of it or for decclerating and quicker shift/downshift recovery (not to mention less abuse of the trans and clutch themselves). In a properly geared (final drive) chassis a lighter wheel makes sense for what I have stated. It will shift faster and it wont beat up the trans because it will take less effort to slow down or speed up the input and cluster... and the wheel itself.

It can however, be a PITA for some street set-ups. If you dont get the gearing right or you go too light on the wheel, stalling and chatter upon initial enguagement will be the most common complaint. Gearing in the transmission and differential, chassis weight and clutch type will be big determining factors in this decision.

As for a drag race type set-up, you, for most applications would want to run a heavier wheel to kinda 'store' the energy to help get the mass moving and get it out of the hole. This also however, puts more strain on the drivetrain and slows shifting (not to mention beating the syncros up a little more) but there is nothing wrong with a correctly weighted steel wheel.

Lighter chassis = lighter wheel
Heavier chassis = heavier wheel (3500#'s and up)

[Blown353]

A 30lb flywheel is a bit "porky" IMO.

I run a 20lb Mcleod steel billet flywheel in my 3600# car with relatively tall 3.42 gears and the 3.27 first in my TKO and I can launch the car by just letting my foot off the clutch from idle and only having to slip it a tiny bit. I can't imagine how "lazy" the engine response would feel with a 30# flywheel!

Given your car is probably very close to mine in weight, you have the same 1st gear in the tranny (don't know what your rear ratio is but I'd assume mid 3's) I'd try to get a flywheel in the 20lb range. My personal feeling is that 30# wheel is just going to be lazy but the 13# flywheel might make things "tricky" in stop and go traffic.

If you aren't dicing in stop and go traffic much and not drag launching the car with slicks I'd probably go with the 13# flywheel though and live with the launch you get because shifts and engine response will be great with the 13# flywheel.

[formula]

Alright, thanks for the advice guys. I wasn't aware of the clutch engagement issues a lighter flywheel can bring, and since my car is a street car first and a track car second, backed currently by a measely 3.08 posi, I have a feeling the 13 pounder will be too light. Now I just have to hunt down a 12", 166 tooth flywheel for a small block chevy that's around 20 lbs...seems like everything is either sub-15 or 30+.

[Blown353]

Check with McLeod. I'm running a 153 tooth flywheel because of starter/header clearance issues (with a 168 tooth my starter hits the headers) but the 153 tooth flywheel I have is drilled for the larger clutch.

With your 3.08 gears and a 13# flywheel the car would be a little tricky to launch in my experience, but not *too* horrible.

[chicane67]

10,000RPM and Fidanza are also two other excellent productlines that offer various weights along with material selection.

[formula]

Any guess on how far up i should step my rear gears to improve things, if i were to go with the lightweight one?

[Skip Fix]

My high school daily driver was a 64 409 Impala SS with a 15 lbs Hays(flywheel in my 79 Camaro 383 autocross car now). It drove fine, no chatter but I had 4.10s and a 29" tall tire. It cushioned the launch and never broke the Muncie and ran 12.20s @ 108 in 1972. Had a heck of a top end acceleration also since it didn't have to accelerate a heavy wheel.

[ProdigyCustoms]

To add to what Chicane said from personal recent experience. Prodigy runs a small block style 153 Aluminum flywheel. It is pretty small and pretty light. Originally when we bought the clutch we planed to do 3.73 gears, but as the budget tightened heading into SEMA, we left the 3.00 gear in it until after the show. Long story short, that gear combined with everything else made the car EXTREMLY hard to launch, even from a stoplight, even with 540 inches, 674HP and 635LBS of torque in a relatively light car. In no time we roasted the clutch. After we changed to the 3.73, the world became a happy place. We would have it no other way. But what a miserable bitch with the wrong gear!

On another note, the 55 we did some work on was set up by another mechanic with a million pound wheel, a cast POS at that. It was having crunching issues between gears. We tore it down, found the cast wheel, and put a nice Hays aluminum wheel. Not crazy light (don't remember weight) but surely light. Made a new car out of it and reved MUCH faster.

[Steve1968LS2]

A lighter flywheel will get you going slower but once you are moving the car will respond quicker.

I am running a alum FW that weights 15lbs.. the steel one weighed 30lbs. I am also running 3:70 gears.

It will most likely be harder on the clutch but the engine should rev like a mofo. The heavier flywheel stores more energy and is often prefered by drag racers for better launches. The light ones are more prefered by road racers where the car is in motion, and reving most of the time.

Some flywheels are crazy light and I would stay clear of those..

[vanzuuk1]

So what is a good compromise, what are most guys running with a small block and gears around 3:55 ish? Is twenty pounds about average?

[TheJDMan]

Now I just have to hunt down a 12", 166 tooth flywheel for a small block chevy that's around 20 lbs...seems like everything is either sub-15 or 30+.

11" is the biggest clutch you can go with a 168 tooth flywheel for a SBC. I have never heard of anyone making a 12" clutch for a SBC unless maybe a truck clutch.

[FlyDoc]

I have a Fidanza aluminum flywheel and their stage 2 clutch in my camaro, I love it, I auto X, and street.
drive train is a LT1 with tune, intake & headers, T56, IRS with 3:42 & 29" tires, I do get some chatter if I don't have the RPM's and let the clutch out to slow. It just take time to learn how to drive your car again. I also got an increase in gas-mileage of about 1-1 1/2 when driving it like a law abiding citizen.
Just do it!