Lighter flywheel for two reasons?

[IsaacCarlson]

I have been searching the forum for flywheel tech, and have come up with this.
In a manual trans you want a heavy flywheel to prevent stalling when engaging clutch. But at the same time a heavier flywheel takes more energy to get up to speed. If you are going through 4 or 5 gears you are spinning that flywheel up to speed 4 or 5 times in a row and wasting a LOT of energy. I just did some research and found out the flywheel in my auto weighs 30 LBS!!!!! The aftermarket FW weighs in at a whopping 14.9 LBS!!! THATS HALF THE ENERGY TO GET IT MOVING. If i consider the fact that my car weighs just under 4,000 LBS i need to cut as much weight as possible. A lighter flywheel would also make starting a LOT easier, especially in winter. Oh, and then you have better throttle response too, and maybe quicker 0-speed limit times as well.

EDIT: Oh, and you would probably have less body roll in corners and less stress on engine mounts because a lighter flywheel would have less resistance to change of axis compared to a heavy beast.

I just think lighter FWs make sense on auto trans cars.

please let me know if i an wrong but please don't spout off if you have nothing to back it up.

[MadisonMPG]

I don't think that you would see less body roll. But I think lighter flywheels are a good thing.

[SVOboy]

I didn't even know they had real flywheels in automatics since the one I took out of my CRX was basically as flimsy as a pie pan

I say go for it

[orange4boy]

Flywheel lightening is a standard mod in racing and it translates to better FE. I did it on my VW bug and the thing revved up MUCH quicker and gave a seat of the pants acceleration increase.

It's similar to reducing the weight of your rims but more effective because of the gearing. Rotational mass reduction in the drivetrain is usually a good thing. I can never remember the ratio but one pound of rotational mass is worth several static pounds. If you are a good stickshift driver, you won't notice much difference in a manual. Idle may be a bit more lumpy though.

[MadisonMPG]

Originally Posted by orange4boy

Flywheel lightening is a standard mod in racing and it translates to better FE. I did it on my VW bug and the thing revved up MUCH quicker and gave a seat of the pants acceleration increase.

It's similar to reducing the weight of your rims but more effective because of the gearing. Rotational mass reduction in the drivetrain is usually a good thing. I can never remember the ratio but one pound of rotational mass is worth several static pounds. If you are a good stickshift driver, you won't notice much difference in a manual. Idle may be a bit more lumpy though.

I think it's 1lb is 3lbs, at least I feel it is that way with tires.

[aerohead]

With my first Karmann Ghia,I had the flywheel shaved for the same reasons as you mention.With meticulous record keeping,and a big baseline for the car,I could never distinguish any benefit at the pump.The inertia of the flywheel,compared to the overall mass of the car and moments for the other rotating components evidently was below the threshhold to affect any measureable improvement.Wish it had been a different outcome,as the whole exercise was very costly to me.-------- Hope you have better luck.

[JeepNmpg2]

I almost did this for a compact pickup I used to own, but decided against it, because it gave me all of the initial take of torque when I had a load. O would stick with the heavy stock one unless you don't ever plan on carrying many passengers or cargo and starting up hills :P

[Frank Lee]

I always wanted to try a HEAVIER flywheel on my rig. My reasoning is it wouldn't buck so much when down in "lugging" rpm range. I skip-shift AND short-shift a lot anyway so I doubt the "accel/decel losses" would be an issue.

[Frank Lee]

Originally Posted by IsaacCarlson

I just did some research and found out the flywheel in my auto weighs 30 LBS!!!!! The aftermarket FW weighs in at a whopping 14.9 LBS!!! THATS HALF THE ENERGY TO GET IT MOVING. If i consider the fact that my car weighs just under 4,000 LBS i need to cut as much weight as possible. A lighter flywheel would also make starting a LOT easier, especially in winter. Oh, and then you have better throttle response too, and maybe quicker 0-speed limit times as well.

EDIT: Oh, and you would probably have less body roll in corners and less stress on engine mounts because a lighter flywheel would have less resistance to change of axis compared to a heavy beast.

I just think lighter FWs make sense on auto trans cars.

please let me know if i an wrong but please don't spout off if you have nothing to back it up.

NO automatics I've ever heard of have flywheels! They're called flex-plates and usually do nothing more than provide a place to attach the torque converter and the starter ring gear.

I never heard of 88s with stick trannies???

As for body roll in corners, flywheels/flex plates/torque converters are oftentimes about the lowest components to the ground there are. You'd likely see a bigger effect on vertical CG by mounting your battery lower in the chassis.