aluminum flywheel

92redsc

Registered User
has any one had any good or bad news with a aluminum flywheel. my friend has one on his ricer and he said it felt like he gained 20 HP while under WOT. just wondering if it would do any good on a SC
 
On a small tin can it would make a world of difference but on a beast like ours I would tend to lean more towards keeping the stock one. I don't have real world experience with this but I have with a bigger and smaller convertor. You see the rotating mass actually helps to get your car going. Someone might be able to chime in here with a stick but with my smaller convertor, I went with a 10", my car would get out of the hole for !@#!. But when I switched back to a 11" it really pick up my short time, stall speed and manufacturer were the same. So basically I would stay with stock.
 
I've got one on my 91 5 spd. I think they're great.
I'm not sure how much I gained from it cause I put it on when I did a whole mess of other mods at the same time.

Some folks say that you won't be able to idel without the mass of the stock flywheel. Mine idles fine. Some say that the mass of the stock one actually helps because it has momentum. That momentum comes from somewhere, it comes from the engine. The engine has to put the energy into the flywheel to get the big thing spinning. Every time you shift gears, the engine is using horsepower to spin the flywheel. The more hp it takes to spin the flywheel, the less there is that gets to the rear wheels.
 
Aluminum flywheels will hurt your lowend torque. They are good for high strung little rice motors that need to get up in RPM fast but are exactaly the oposite of what your big heavy car needs.
Anybody that says a engine wont idle because of an aluminum flywheel is an idiot!
Horsepower does not spin your flywheel, TORQUE does.
HP does not controll your acceleration, torque does!
Forget HP! Torque is what you should be increasing. HP means nothing, unless youre only concerned with going at and maintaining a constant speed.;)
 
An aluminum flywheel will NOT hurt low end torque. That's just crazy talk.
They only advantage to having a large mass rotating is when your about to launch and you are reving the engine (and flywheel) and so you've stored up potential energy in the flywheel. Then you dump the clutch and that energy gets transferred into the trans. But once that takes place and the RPMs drop, the engine has to put MORE energy (torque) into the flywheel to get it spinning again. That's torque that never gets to the ground. So if all you want to do is break your tires loose, go with the heavy flywheel. If you want your car to accelerate faster, go with a lightweight flywheel.
 
Slysc said:
An aluminum flywheel will NOT hurt low end torque. That's just crazy talk.
They only advantage to having a large mass rotating is when your about to launch and you are reving the engine (and flywheel) and so you've stored up potential energy in the flywheel. Then you dump the clutch and that energy gets transferred into the trans. But once that takes place and the RPMs drop, the engine has to put MORE energy (torque) into the flywheel to get it spinning again. That's torque that never gets to the ground. So if all you want to do is break your tires loose, go with the heavy flywheel. If you want your car to accelerate faster, go with a lightweight flywheel.

Sly just read the thread George posted, TBK admitted that he lost low end torque. Nowhere did I say it would completely kill the lowend power of the motor.
Way back in the 70's we used to put the aluminum flywheel in if we were going to a slick track in order to hook up because it lowers low RPM torque just like I said and just like TBK said in the thread George posted. What is crazy is your theory about how it all works. You need to do alittle more research before you start calling people crazy!
 
I am on the side of thinking the lighter flywheel doesn't hurt torque. I've got (nearly) the same flywheel as TBK in that post, and we installed them at the same time. There is NOTHING that even hints to me that torque was lost.

While I haven't done any Dyno tests, I did put quite a few miles on the lightweight. I have made a few posts about my driving experineces with it on the TBSCEC site, so they should be in the member only forums now.

Performance has increased across the band, from idle to redline.
 
The only thing that helps you pull it off without too big of a hit is that Eaton M90 setting on top of your engine, if it was'nt there it would be very noticable to you and you would be singing a different song.
But to say that it makes NO difference is not true and that dyno you spoke of will prove it.
 
The only thing that helps you pull it off without too big of a hit is that Eaton M90 setting on top of your engine, if it was'nt there it would be very noticable to you and you would be singing a different song.

I cannot disagree with that at all. The spinning M90 provides quite enought rotational inertia, along with the, still quite heavy, pressure plate.

But to say that it makes NO difference is not true and that dyno you spoke of will prove it.

This is correct, switching to a lighter flywheel does indeed make a difference, Engine output is increased, as I said across the band, from idle on up. All that is given up is the capacity to store energy, and the SC does not need that excess capacity in my opinion. The mass of the flywheel does not produce torque, the chemical reaction in the cylinders does. Giving up the mass does not give up the energy produced by the engine, it just gives up the energy stored. Once the clutch is released stored energy means nothing, what is moving the car is energy produced. More of this energy is available to move the car since it is not required to accelerate the spinning mass of the flywheel.

No driveability is lost whatsoever. If Deep6 happens onto this thread he can comment since he drove my car a bit at Carlisle just after I put the lightweight in.

I beleive last year some magazine did some testing on lightened flywheels...Maybe Carcraft. They dispelled the rumors of lost torque. maybe it is online somewhere.....

It would be nice to see a specific before and after dyno test on an SC, but I can't do it. I no longer have a usable stock flywheel, and I don't know if I would be willing to go through the work of swapping out flywheels, and pay for two dyno tests to prove a point...
 
A lot said but how do you explain what happened with my car. Smaller convertor, same stall lost almost .2 in my short time. Why would that be? I'll have to strongly disagree and leave it at that Andy. If you have the traction the rotational mass WILL help you get off the line, with traction and if you notice with any of our SC's, if you don't get a good launch then you lose big time ET.
 
Imperical Data

I recently installed a Spec. aluminum flywheel not concurent with any other mods.

I won't try to explain what is happening between my right foot and my rear wheels but this is what I observed.

The car definetely cranks through the gears noticabley faster. Throttle response is crisper.

When starting in first or reverse from a dead stop, I have to be a little more carefull with the clutch to not stall it.

Once it is in gear and rolling the car is faster and more responsive - period.

Cheers
Bob
 
Auto are a whole different world, and I admit I don't know a whole lot about them, with the torqu miltiplication and such. I think there might be more to the story than just rotational mass when dealing with a torque convertor. I suspect that there was more of a difference between those two convertors than just the mass.

What I have heard is that "stall speed" actually doesn't exist. What convertors have is a K factor or something. This factor along with engine torque characteristics produes a stall speed meaning two identical convertors will have different stall speeds when installed on different engines. How this might affect your test results I don't know.

More mass CAN help launching the vehicle, if as you say, you have enough traction. You store energy in the spinning mass and transfer it all at once, but then it is just dead weight you are dragging along...

Automatics are black magic to me. don't know 'em, don't like 'em.

All I can offer up is this; after switching to the lightweight flywheel I can light up the tires in 2nd gear by just pressing the gas. No clutch popping tricks, just rolling along in gear and nailing the gas. I couldn't do that with the heavier stock flywheel. To me that means more torque.
 
Perfect example of what we are talking about. Bottom end torque is lower. Probably harder for you to break the tires lose too. At higher rpms it will help but we mainly use the bottom end. I will go with the philosophy that we have enough bottom end torque so losing some to gain top end would actually help the car but it really doesn't at the track because my ET was down by .2 or so also.
 
al flywheel

Don't you guys read the Ford rags?MM&FF did some testing a few issues back both on the 1/4 mile and road courses and there conclusion is that there is not a situation that it wont help acceleration times.
 
Well I really dont care what a magazine say's about anything. They've talked out of there ***'s for years now, if you spend enough ad money with them they will say anything.
I base my opinions on proven data by top engine builders and people I know in motorsports that have a PROVEN record, not magazines. One such instance is a comment made by Larry Widmer when asked about how he decided what HP levels to aim for when building or designing engine parts, Larry said: " I never look at HP levels when designing an engine package. I design for torque as thats what accelerats the car down the track, not HP"
He went on to say " HP is only good for running at a steady speed constantly and therefore meaningless"
About now youre probably thinking, Who the hell is Larry Widmer?
Well Larry is the guy that built and designed the cylinder heads for Bill Elliot when he was King of Nascar and set the fastest speed record at Talladaga. He also put Bob Glidden on top of NHRA Pro Stock with redesigned BOSS 429 heads that he made.
I think that speaks for itself. The man knows what he's talking about, he's no chump!
Funny thing is after Ford tried to steal Larry's work and Larry cut them off from his services both racers success plumeted. Coincidence? I dont think so.:rolleyes:
 
For drag racing I would stay with a stock flywheel because there is no reason to have your RPMs spike or drop quickly during a drag race, unless like previously mentioned about slippery tracks.

If you are going to road race the car then I would suggest getting the light weight flywheel. It would make it easier to match your RPMs for down shifts and slow easier under braking while in gear.

In a large car I would want the heavy flywheel. In a small light car I would go with the lighter flywheel. But either way I doubt that the difference will be hugely reflected in the numbers.
 
The swap from a 12" stock stall (1800-2000) non locking Lentech converter to a 9.5" 2600-2800 stall non locking Lentech converter, had no negative impact on bottom end torque.

In fact, it increased torque because of the increased slippage. I did dyno the car shortly before and after changing converters. There was no improvement in peak HP but the torque was higher and remained higher all the way to 6000 rpms. The engine also revved much quicker and that was especially noticible on the dyno.

The smaller converters can not be made to stall as low as a large diameter converter. I can't explain Aarons losses in the first 60 ft, but I suspect it was related to stall speed.

At the time I did notice that the reduced mass and higher stall of my new converter made it harder to spin the tires on the shift into 2nd and nearly impossible to bark the tires shifting into 3rd. However on the track my ET improved about 3 tenths but I also lost about 3 mph thru the traps.

I really don't understand how losing weight on the flywheel or converter would reduce torque. Then again I still struggle with the difference between torque and horsepower, so don't pay any attention to me.

David
 
What was proven 30-40 years ago...Can easily have been dispelled since then...The inertia of the heavier flywheel will without a doubt help initial launch if launching at a high RPM.Besides that it WILL EAT UP POWER ..Its the 21st century now guys get with it!!!
 
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