gdh

My vette came with a 12 3/4" flywheel vs the std. 14" LT-1 flywheel. I was told that this smaller flywheel results in less "flywheel effect". I can quite easily stall from trying to ease away from a stop sign. I have a vague understanding of what "flywheel effect" means but would be happy if someone could explain it in layman's terms, ie. pls don't use the term kinetic energy vs rotating mass.

79VetteMike

Sounds to me just that it means more centrifical force. You can probably take a 10lb weight and spin it around more effortlessly in in a circle than you could a 25lb weight. Less weight means less efficiency of the rest of the system is lost. It's just a guess, so I could be wrong....


[Modified by 79VetteMike, 5:56 PM 8/29/2003]

427Hotrod

To fix your "stalling" issue, you want a heavier flywheel.

The easiest way to say it is that it is harder to stop or slow down that heavier flywheel than it is a lighter one. Once it's turning it's hard to stop. It "stores" more energy.

Kind of like if you try to stop a 5000 lb car from 60 mph vs a 2000 lb one. it's a lot harder to do!

Now the converse is true also...that heavier flywheel is harder to get turning too. It takes more power (ie Longer) to accelerate it.

Reality is that most street cars with reasonable gears do well with a heavy stock type flywheel. They are much easier to drive, less bucking etc. That's what it's there for...to help get it moving. If you're going serious racing, then SOMETIMES a lighter flywheel is better. But only if you are making lots of power. If not, then when you shift, the lighter flywheel doesn't have enough stored energy built up to keep the engine rpm from sagging down too low and the car falls out of it's powerband and actually runs slower.

Many drag racers used to, and still do install heavier (50 lbs) flywheels to help get a little engine/large car moving off the line.

Hope this helps,


JIM

73 LS-4

It all has to do with inertia, a smaller lighter flywheel is easier to spin up and also slow down then a larger heavier flywheel. Becouse it is lighter it's easier to slow down, therefore it takes less load to stop it. The load being trying to move the car. A heavier flywheel spun up to the same rpm can exert a lot more force therefore it's harder for it to stall. The disadvantage of course is that it's also harder for it to get up to speed. IF you have ever driven a lot of trucks with manual trans you'll notice how the RPM doesn't come down real quick when the clutch is pushed in, this is due to the time it takes for rotational forces of the engine to slow down, including a heavy flywheel. Now a high rpm engine with light internals and small aluminum flywheel will almost go to an idle as soon as you touch the clutch becouse of the far less inertia from the light components.

hope that helped
:cheers:
Pat Kunz

Matt Gruber

with the 383 you have some other problem.

gdh

thanks guys I now understand. :cheers: you have explained it much better than any write up I have seen on the LT-1/ZR-1 option that my vette came with. I guess then that the smaller fly was for both weight reduction and a faster throttle response and you are right the rpm's sure do drop fast on shifts.



[Modified by gdh, 9:14 PM 8/29/2003]

gkull

I'm with Matt 383 has more grunt. Try turning up the ignition advance 2-4 degrees - which should also speed up the idle. Adjust your Carb A/F idle screws to the highest vacuum.

What is your idle rpm?

gdh

idle is about 750 right now