What's the real story?...aluminum vs. steel...

...in flywheels. The Ramrods are thinkin' about using an aluminum one to save weight and to let the flatty rev quicker, but we've also been told that a steel one will get the car launched faster with all that spinning weight. What's the real skinny?...

 

Heavy steel keeps inertia up on a drag launch, light aluminum lets a road racer recover rpm quickly at gear changes and corners.

 

An aluminum flywheel will allow quicker revs, but is less forgiving when engaging the clutch. Just don't embarrass yourself and stall it on the line! Practice, practice, practice.

 

A really light car with a lot of gear will want the light flywheel.

Heavy cars need the inertia of the heavy flywheel to get moving. A lighter car with more gear will just spin the tires... and the engine will be harder to rev than it needs to be.

 

I've wondered about this too.
I've had two different guys WHO KNOW (Lamar Walden--engine builder, former Pro Stock racer, been around forever, and another guy who pro raced in the '60s/'70s and owns an original S/S Hemi Barracuda) tell me that for my race 409 I should run an aluminium flywheel. Lamar is building the engine, and he doesn't want me to look stupid with his engine.
My car is a lightened '57 Chevy wagon (less than 3,500 lbs with driver), the engine will be 482ci, and will make shit tons of torque. So the way it sounds to me is that when the RPM is up on the launch, the engine will be able to make enough torque that it should drop down to or just below its powerband when I dump the clutch and the tires hook.
Must admit, I'm a bit scared with the prospect of launching a 409 at 5,500-6,000 though...

For something light with an engine that isn't going to scream...I dunno. I understand the concepts involved...I'd say it depends on the rpm you're going to launch the car at and what kind of traction you have.
It's not exactly a budget approach, but having both flywheels and testing each would give you the surest answer.

-Brad

 

Hey Larry,Having tried both I can assure you you want the aluminum with a steel insert.
Having said that,you all know you wanna do it and at the risk of ridicule for using a modern redneck cliche', "GIT ER DUN".LOL
Should I bring the CH3N20 to the next test session?

 

HAY larrrrrrry the HORNETS have 300 lbs will loan you NORTH SIDE BOOOYYYSSS to get herrrrr to hoooook up




bobbbbbby the BS HORNET

 

This is a marvelous debate. I'm guessing that a HA/GR wants a light flywheel because of the tire limitation. Rod Urish's flathead powered Anglia uses a heavy flywheel for the launch and it makes a serious impression. However, he has some healthy slicks and is running a four speed, so he doesn't lose as much rpm between shifts. Back in the '60s, I used a heavy flywheel on my flatty drag car, again for the launch, but there were no tire limitations and it was a heavy car relative to the power available.

 

Heavy flywheel is a bandaid. You only need it if you are down on power or up on weight. A light flywheel car will accellerate faster. Also, winding up a heavy flywheel and dumping the clutch has been known to break things.

 

There's a security factor with a steel flywheel. As stated, the intial launch is stronger. If you miss a gear it will give you a chance to get off the gas before you hurt it from too much rpm. The light flywheel engines sound cool but it will let the engine go to outerspace if anything goes wrong. The drag racing technology in the 80's was that after the intial driveline shock, a heavy flywheel was easier on all the components. It really depends on your application rather than a hard fast rule that fits everything. An engine with a radical cam and real light flywheel will have trouble idleing at a reasonable low speed.

 

Here's the deal:

Back in the day, racers shaved the snot outta their stocker flywheels to save weight. The reason saving rotating weight is important is inertial loading - it takes energy to spool up that flywheel - energy that, once freed, is available for the rear wheels!

using an aluminum flywheel really is the shit - the motor will rev faster and more power is available to the rear tires. Dragsters do indeed swap out iron wheels for alloy ones - a friend of mine runnin' F/S dropped in an alloy wheel and went faster. The downside has been mentioned - a light wheel IS harder to launch than a heavier iron wheel, and will take practice to get it 'right'.

The difference between an alloy wheel and a light iron one? about 10 lbs. Iniertial loading means that 10 lbs dropped will 'feel' like 40 lbs lifted off the car.

 

I think it's worth trying. If you don't like it, sell it on ebay. You won't be out too much. A light wheel makes a big differance in a circle track race, when you need a burst of passing power. It may not work as well in a drag race, it might just do the trick. It's hard to tell unless you try it.

 

I would highly recommend you don't try lightening a stock cast iron flywheel. Back when that was common, explosions were also common. The reason blow proof bellhousings were invented was clutch explosions. Rpm causes the stress loading to go up way more than a cast iron flywheel was designed to take. If you have a steel flywheel that is aftermarket such as a Hays or Mcleod, you can lighten it some but finding out if you went to far is really painful. A standard chevy flywheel used to be around 24 to 28 lbs. The aluminum ones I used weighted 12 lbs. Someone probably has a copy of a chart I saw in the 60's that listed amounts that supposedly were safe to remove from the common flywheels used then.

 

I think your engine will be happier with the aluminum flywheel and steel insert considering the 6" tire rule. If your billfold is like mine it will prefer the steel.

 

brand new car and you still can't get it to go, eh? I guess I don't have much room to talk......mine still has a ways to go.

 

# 1 do not cut weight off of a stock cast wheel! Balance guys will drill holes after trying to index the PP to minimize the amount removed from a stock wheel. You can safely cut tons off of a steel wheel. I have seen a 70 pound wheel in a small block chebby gasser (40 years ago). Regardless it is not a big deal to try both. My 38 flattie has a fairly light 9" diameter steel wheel (disc) and my 52 PUP has an 11"...
It is not unusual for a modern fuel car to have a clutch that weighs 70 + pounds.

 

They probably solved the issue long ago as the post above yours was FIVE YEARS AND NINE MONTHS OLD!! Then you wonder why we call you FNG's

 

Don (Big Daddy) lost part of his foot with a clutch/ flywheel explosion! I talked to him right afterwards he was going to get away from those D_ things! So out came his rear engined dragster.
We had several of lightened flywheels come apart in the 60's and 70's. Shrapnel holes through the dash boards, windshields, and holes in the strip! Do not try to do those!!!!!! Buy a USA mfg'rd assembly if your gonna drag it. If it is for the street and you just wanna be neat use the steel wheel. If you are gonna road race it then the Aluminum. Stock cars use the aluminum. They are light geared right and need it to turn up quickly! I would not use an old Ebay aluminum flywheel! Use the newer steel inserted one!

 

I love the aluminum flywheel in my big block Dodge Challenger!! It's a freaking rocketship!!!

I want one for my 1956 Chevy!!!

BANG!!! ZOOOOOOOOM!!!!!!

 

OK! You all are answering one of MY questions!!! What is an FNG?
I am answering these as they ARE showing up on the HAMB under new posts!!!!!
WHAT is the deal? Somebody please PM me as I most of the time do not go back and look at the old posts that I did as I do not have the time to just FART around. I am an active shop and am busy!!! I am just trying to help with my years of hard earned experiences! Believe me it cost plenty of $$$$ to LEARN!
Joe at Autoworld Corportion
Your Restoration Destination!

 

UMMM....he's been here longer than you have

 

just as relevant now as it will be tomorrow to someone building a motor-- the issue that is settled is that you ODL OVERPOSTERS ARE BORING WHEN YOU DO THIS

 

Well now, this grenade inspector would respectfully like to know what it the time limit to respond to a thread? Would 1 day be OK or possibly more? Just askin.