[SWEETJUDGE]

Guys every once in a while i come across aluminum flywheels for 4 spd cars.....

whats the advantage? & when does it make sense to use one? is this a light car advantage thing only ??? or do heavy cars benefit aswell?????

[punisher#1]

i have used these on small block fords in autocross and road race applications. it allows for quicker engine acceleration coming out of a turn. they don't work too well in drag applications unless the car is very light. you need some amount of weight to keep the crank spinning between shifts and to keep it from slowing down at the launch.

[BILL BOWMAN1]

I'm no expert but-
Throttle respone is improved, I think you would need a higher numerical rear gear. Probably not a great idea in a heavy car as the flywheel is rotating mass and will help get it rolling.

[SWEETJUDGE]

i remember swapping a steel for aluminum in our boat......... which is a whole nother story......

ok so for a stock wieght car stay steel ......

thanks SJ

[J.C.you]

alot of variables, but it was worth about 12ft pounds torque on the dyno on a EM entry.

[60man]

Originally Posted by J.C.you

alot of variables, but it was worth about 12ft pounds torque on the dyno on a EM entry.

Hmmmmmm....not doubting you but that doesn't make sense ??
You can generate a lot more power swinging a big hammer than you can with a little one ??!! Granted the motor will free rev quicker but you better have some stiff gears or a light car to use it in real life JMO..
I had a bud that had one in a 62 GP 318 HP wide ratio 4-speed with 4.10 gears.....it was still a dog on the street. The only way to take off was rev it up and dump the clutch...and nail it !
It came out one day later.
Obviously it has a place ...somewhere...not in a heavy car for sure..

[gtofreek]

Originally Posted by 60man

Hmmmmmm....not doubting you but that doesn't make sense ??
You can generate a lot more power swinging a big hammer than you can with a little one ??!! Granted the motor will free rev quicker but you better have some stiff gears or a light car to use it in real life JMO..
I had a bud that had one in a 62 GP 318 HP wide ratio 4-speed with 4.10 gears.....it was still a dog on the street. The only way to take off was rev it up and dump the clutch...and nail it !
It came out one day later.
Obviously it has a place ...somewhere...not in a heavy car for sure..

It makes more torque and HP because less power is being wasted trying to spin the heavy flywheel. It makes more power on a dyno, but in real world street driving, you need the inertia from a heavy flywheel to help get going. As was said before, they have their place in circle track or road racing where rpm's are kept up and quick acceleration is needed.

[68birdfreak]

I have a billet aluminum F\fly wheel in my 69 bird and love it....rotating mass robs power and blah blah blah...I love the power outta the corners and when i downshift and slam it...holy chit! Greg Merrick put one on my 440 and the beast revs quick!

[Jack Gifford]

Originally Posted by J.C.you

... worth about 12ft pounds torque on the dyno...

That's obviously on a "sweep" dyno pull, with the engine always accelerating. Were you to do a traditional "brake" dyno pull, loading the engine to a constant speed for each torque measurement, flywheel mass would, theoretically, have zero effect on torque.

Reflecting on what I just said- reinforces my distrust of "sweep" torque measurement. To provide accurate results, too much depends on the software capabilities. If a dyno's software were as comprehensive as it "should be", it would demand that the user input the value of the polar moment of inertia of the crankshaft and everything that rotates with it- dyno coupler, etc., and including of course, the flywheel. Given this data, true engine torque could be calculated- and the 12 lb.ft. differential referred to would disappear.

[sdbob]

I ahve a 67 400 4spd Firebird that just sits.It was a stocker drag car . I have been thinking about DOT stocker.Sounds from the info the light wheel would help this car on red lines when drag racing a pure stocker. Any thoughtsfor this setup? The car does have the 4:33's stock.

[J.C.you]

i wonder why in 2006 only STEEL flywheels were allowed in EM? think there may be an advantage of alum over steel on the dyno?

http://www.popularhotrodding.com/eng.../photo_05.html

[70judgeconv]

A heavy flywheel will give a mechanical advantage to a heavier car comming out of the hole or on launch. An aluminum flywheel will help acelerate a light car by reving quicker
and not bogging down due to the weight it needs to move.

[60man]

Originally Posted by 70judgeconv

A heavy flywheel will give a mechanical advantage to a heavier car comming out of the hole or on launch. An aluminum flywheel will help acelerate a light car by reving quicker
and not bogging down due to the weight it needs to move.

Exactly.....I agree with that...takes torque to get going and HP once it's rolling..
A light car,stiff gears,and a short stroke quick reving motor should be cool. Ok for road course/auto cross or "lightweight" drag car..Just merely pointing out I wouldn't try it on the street..that's all..

Like I said...everything has it's place..

[tom s]

had one in a 63 421 Alu SD car with a 3.42 in the back.HATED it,was always stalling it from a stop.Put a steel one in, was great.JMO,Tom

[Old Goat Racer]

My 78 TA has a Hays alum. behind a 455/96 head, 068 cam, headers, 3.42 gears. Once in a while, a stumble at the stop light, could be carb related. 13.20s @ 103. Working AC.

[Old Man Taylor]

I don't like typing a lot so I will just paste in a response I wrote long time ago.

"Too often people only consider one aspect of a change, especially in the case of an Aluminum flywheel. There are three operating characteristics to keep in mind when considering using an Aluminum flywheel. 1. Getting the car moving from a dead stop on the street. I believe a minimum overall first gear ratio of about 9.5:1 is a good yardstick, otherwise you have to slip the clutch too much. 2. Racing from a rolling start. The tires will start spinning much easier due to less rotating inertia. Using rear tires with more traction can cure this. 3. Launching from a dead stop, with or without slicks. The Pontiac has a lot of rotating inertia in the crank. It will be much easier to spin the tires with a heavier flywheel. This is not normally an issue as most of us want to limit tire spin because of the low end torque our engines produce. However, with an Aluminum flywheel, once the tires start spinning, it is easier for them to continue spinning harder as the engine will rev faster. I have used an Aluminum flywheel for a long time in both 400’s and 428’s. As long as the overall gearing is OK, the number one down side I have experienced is traction from a rolling start with DOT street tires. Even with this problem, I love the light wheel."

[Junkyard Dog]

Originally Posted by Old Man Taylor

I love the light wheel."

OMT, your cars were not less than 3,000 pounds, were they?

[OINK 1]

You use them for road racing,. Faster pick up, use motor to slow down for turns, saving brakes.
I have custom made units, 11 pounds, sfi certified, made in the USA !!

Pontiac Gregg

[Mr. P-Body]

One more thing to consider. While it takes less power to get it spinnning, therefore "saves" some of the parasitic drag, a "heavy" flywheel STORES inertia, thus the better performance in launching a heavy car. Gain one place, lose in another... No free lunch!

I agree with Greg, road racing is where they "shine". Some circle track applications too, but most run automatics these days (or the little "QuarterMaster").

In a light car, it's not a bad deal. In a heavier car (over 3,000 lbs.), the steel one would probably be the better choice.

Jim

[Skip Fix]

Hays aluminum flywheel 3860 lb 64 Impala SS 12.20s @ 108. Street driven daily to school and threw paper from it so ALOT of starts and stops even with a big a$$ solid cam. 9" cheater slicks and a 6000 side step for launching at the track. That was before VHT days though so there was a little spin, A car had better launch pretty good on it as the light wheel it would pull like a freight train all the way down the track.

It's in my 79 Camaro SBC autocross car that is coming out for the 500" IA2 and a TH400.