Hot Rods Are there long term effects for too heavy of a flywheel?

I have an old vintage Hayes flywheel for a stick. It's a heavier flywheel for drag racing. Any long term effects on bearing life etc? I would love to run it if possible.

 

How heavy is heavy?

 

I would think that if it is in balance there would be no problem. The Nomad in my avatar had a 41# flywheel on a built 265" sbc, and it worked real well with the exception of it was rather slow to get higher revs out of it.

 

Flathead flywheels are pretty heavy to begin with and only run on 3 mains, but I'm not racing.
I would thing having a good balanced ***'y would be the key to longevity and a good inspection (magnaflux?) of the wheel and blowproof b-housing. Wouldn't want that coming through the floor.

 

You didn't state what engine you have.. But, I used to get in industrial flatheads for rebuilds, back in the day. Some with flywheels you could barely lift (even when I was forty+ years younger) and no bearing damage after years of 2800-3400 rpm. almost constant use.

 

I always thought flywheels were lightened for racing. You should see some of the flywheels they run on tractors, too heavy to lift by hand.

 

I just weighed it. 45#.
It's a 265 Chevy, balanced bottom end with forged domed pistons. I was planning a 5 speed behind it for fun factor. The heavier flywheels tend to help launch lighter cars with small cubic inches or so they say...

 

launches harder if you rev it and drop the clutch. when the engine slows, the flywheel gives up energy. When it revs back up, the engine puts energy back into the flywheel.

The net gain/loss depends on the rpm through the lights, vs the launch rpm. If they're pretty close, then it doesn't matter how heavy the flywheel is--it will end up with the same energy is starts with. Energy is conserved. If the final RPM is a bunch higher than the initial RPM, then you have to add more energy to a heavier flywheel, energy that is not going to accelerating the car.

That's the physics lesson. But the actual results will depend on a lot of other variables.

as far as bearing wear, etc, there should be negligible difference, ***uming it's balanced properly.

 

The physics suggest to me that the forces in action to make it spin from a dead start are a function of the acceleration which is a low value thus negligible. Once spinning, changing the rpm is also a matter of acceleration (not velocity) which again are low so again likely to be negligible. The upside is that a heavy flywheel will make an engine seem to run smoother because the larger rotating m*** is less affected by small vibrations like a misfire, etc. The downside as noted caveman is the rpm response time is lengthened. Regarding safety, I think any flywheel of any weight that disintegrates and flies through your floor boards is dangerous. Can't say that a heavier flywheel is more dangerous, they all are when they fail.

 

Years ago I had a 301 Chevy with Rochester Fuel Injection, Duntov cam and fairly high compression Jahns pistons. I built the engine for a '57 Belair that weighed around 3300 pounds and it was tough to launch without revving to 5K. I pulled out the Aluminun flywheel and replaced it with a stock Chevy 11" ***embly that probably was close to 50 pounds and it would launch at 2K. The only problem was it took longer to rev up. That clutch ***embly was still in the car when I sold it three years later and held up to the abuse. I say run it.

 

Flywheel lightening and its impact on engine performance.-- Read more at: https://www.torquecars.com/tuning/flywheel-lightening.php - (c) TorqueCars

This was a pretty interesting read on this topic, it really depends upon how you plan to use the car. They like the idea of lightening the driveshaft, lots of rotational m*** there.

 

It's a street car. The history is this. The motor was in dads C/Gas car. It held a National record for a few months. I know it is nothing compared to today's motors, but it is as traditional as it gets. A 1955 265 with a tripower and a stick. The flywheel was mated to it when it set the record. It was also the first motor we ran in the Fly.

 

While a driveshaft might have some m***, it's a small diameter so it's not a big contributor.

 

it's lasted 60 years, and now you're worried if it's gonna be able to survive a few more p***es?

 

Well, it's been mostly a 1/4 mile at a time.....not a lot of miles to check for reliability.

 

I've had heavy flywheels my whole life. My discs are bulging, and I have stenosis.

Sent from my SM-G900T using H.A.M.B. mobile app

 

You should see a doctor about that.

 

I haven't priced a explosion proof bellhousing in a long time. Wow! They have gone up.

 

I dropped one on my foot once. I wish it had been lighter.

 

Well Root here is some food for thought, there are companies marketing heavier flywheels for Harleys these days. I have spent my life making the lower ends lighter. "light bike light lower end" was the term when I was coming up. The heavier flywheels are to get the heavy pigs (baggers) that are so popular with the, "all I ever really wanted was a Harley," crowd going down the road.

A heavier flywheel will help you launch or get rolling with a load, The draw back is that any weight on your drive train takes torque to turn. If you don't put an engine that makes a lot of torque in front of it you will note that the parasite is keeping you from reaching your rev potential. In a perfect world a heavy flywheel will be mounted behind a torque monster as opposed to a revver and have tall gears behind it. The heavier wheel will help you pull away at an intersection and the tall gears will get you down the road.

 

I was pondering a 5 speed and a 3.90 gear.

 

Well that will work I suppose as long as your sweet spot is down low. You already know what I am going to say because you know me but someone does not. You never ever want your cruising range to be below where you engine starts to climb up on the cam, IE starts to build torque.

I don't know that it matters but I pulled a 283 out of an old GM dump truck once, it was built on a 2 ton ch***is. The flywheel was by far the heaviest Small Block flywheel I have ever touched. I didn't weigh it but it was a two handed flywheel to be sure.

 

Stock Chevy flywheels I weighed were about 30 pounds.. There are probably other stock wheels of a different weight. A heavier flywheel won't drop as much RPM between slower shifts..and the engine will run smoother at low speeds..

 

I am on the hunt for a WC T-5 from a V8 car if anyone stumbles across one.

 

Maybe on you if you keep picking it up!

 

Back in the "day" heavy g***ers and modifies ran really really heavy wheels. We're talking about 12, 13 or 14 pound cars. i.e. 268" small blocks that weighed 3750 pounds or more. I ran a 268" DM/P with a 40 pound wheel but my car certainly wasn't an exception there where many others with wheels 50+.

 

Feel fortunate that you don't need the one for early (64-67)Chevy 11's.

 

But if the flywheel is real heavy and your rings are worn out it could take several minutes for your engine to stop spinning when you shut it off. Just sayin

 

Yeah, it could freewheel for a while.......

 

I'm running a truck flywheel in my Ford, been using the same set up for eons in various cars. Fairly heavy compared to some I suppose. With a stock engine it contributed to the smooth engine idle. And the clutch had a very nice engagement. My current one uses a Zoom clutch, the PP was balanced to the flywheel.