I posted this subject over in engine mods but got a few conflicting answers. Was hoping some of you could chime in.

After building my internally balanced 383, the machine shop suggested I go with the lightwieght aluminum flywheel from Hay's. Machine shop is locally famous for building SBC stroker motors for circle track racers. I am also running a M21 with centerforce II, and 3.36 rear end gear. Justification was by using a lighter wieght flywheel the engine will rev up faster because the rotating assembly wieghs less. Has anyone here used a lightwieght flywheel? Do you think it was worth it? What performance difference was noticable ? What is the real world downside ? With a lighter flywheel did you have problems hooking up at launch ? Any observations or personal experience would be appreciated.

Thanks in advance

:seeya

 

My motor is very similar to yours . My shop said I wouldn't see much difference so I just kept my steel flywheel. My friend put an Aluminum one in his cobra. He says it makes no apprecaible difference. Seems like a lot of money for not much gain. :flag

 

Your right about the money. Don't have the reciept in front of me but I think I paid $350+. Hope it works better for me. :cheers:

 

TTT

 

Scubajkd,
I have an aluminum flywheel on my 74. If you drove the car you would not know it had a light wieght flywheel. I dont know if it is worth the price, I wuld say not. It does rev up quick and really cracks when you goose it in nuetral. The 3" side pipes has something to do with also.
Ed

 

ED,

So no problems getting off the line or driving in traffic ? My 383 will be running HC headers and 4" sidepipes. Already made the install just have not driven it yet and wondering what to expect. Thanks

 

ScubaJKD,
Alot is going to depend on the rest of your equipment; cam, intake, carb,ect. If it is a good low end torque 383 I doubt that you will notice any off the line problems.
Ed

 

TTT

 

I've put an aluminium flywheel on my camaro with a 350 p.c.. I don't know what was the gain but there was one. From the start, no difference but when cruising at 35 Mph an slamming the gas, the car was quicker to accelerate. I think this mod would be worth to an engine with more rev like over 6500 Rpm as the weight become more difficult to accelerate at these speed. For the price, you would gain investing on better head or something else.

In my opinion, it's a mod that you can do when everything else has been take care of.

Stephan

P.S. The weight of my aluminium flywheel was 14 lbs compare to the 35 or 50 lbs of a stock steel one. I don't remember the steel one but the alu is right.


[Modified by American Boy, 8:03 PM 1/6/2002]

 

I wasn't going to get involved in this - but what the hey...

I love light flywheels. I personally wouldn't bother with an
aluminum one - the nice GM nodular is 15 pounds and stronger
than a stock 30 pounder. The Chevrolet Power book points out that "Chevrolet nodular iron flywheels in new condition have been
tested at 10,000 rpm engine speeds, and are suitable for many
high-performance applications."

I back up my little big block with the small GM lightweight and
I love it. For one thing I feel like it really cuts down on the
possibility of blow-ups. I don't remember which book, but
Smokey said that the odds of a blow-up are way lower with
the small flywheel.

Anyway, back to the topic - everybody seems to be neglecting
your use.

Seems like if you're draggin' you'll want a heavy one.
(Although that might hit your tires too hard? I dunno - I don't
go to the strip). Running through the gears hard probably calls
for a heavy wheel too.

On the other hand, a light wheel makes rolling punches better
(which is what I feel is the ticket on the street) and will help you
slow down faster.

As for the drivetrain abuse - dunno, never really though about it.
Seems like reversing the issue, that the loads from the other side
when braking or down-shifting would be easier on the motor with
the light wheel. Absolutely no idea here - just throwing out ideas.

 

Thanks Steve,

My goal was not to build a 1/4 mile burner although I will make the rare run to the track with buddies. More interested in over all street performance and some autocross.

 

TTT

 

The reason the dirt track crowd like the lightweight aluminum flywheels cause they allow the engine to rev quicker coming out of the turns. For on the street or drag racing, I've heard the heavier the flywheel, the better transfer of torque to the rest of the drivetrain.

Just my .02 though..

 

I ran an aluminum flywheel on my 71 many years ago. It certainly gave the motor a different feel. It did wind up quicker when I mashed the pedal, but was scary when I missed a shift once :eek: (thank god for the hyd lifters and weak valve springs at the time :eek: ) The most significant difference that I found after switching back to the heavier flywheel was the difference in torque when lugging the motor down low(1500rpm) in 4th gear. The heavier flywheel seemed to have a much "torquier" feel in this situation, due to the inertia. I say go for it. Trying different drive train combinations is fun. If you don't like it, it's not all that hard to switch back.


[Modified by tsw71, 4:02 PM 1/10/2002]

 

Well it sounds like it might be kinda fun. Everyone seems to agree it helps a motor rev quicker and not give up that much driveability. However most also say that for torq and drag racing the heavier the flywheel the better. I already have this one installed and ready to go so I guess I will give it a try. Hopefully the torque of my new 383 will help even things out and make it a fun combination. Thanks for all the great replies.

:cheers:

 

I've used a couple of aluminum flywheels and they seem to make a bigger difference on short-strokers like 283/301/302. Had one on a 389 pontiac and the difference was there but not as noticeable.

One thing the 'old-timers' always maintained was that an aluminum flywheel allows the crank to pound the hell out of the main bearings 'cause there's not as much rotating mass to smooth out the combustion impact & harmonics. Makes sense, but I can't prove it one way or another...

 

I may be wrong on this point but I believe that since an aluminum flywheel is so much lighter, there is much less stress on the main bearings.


:seeya