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Cast vs ductile(nodular) vs billet flywheels

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Old 12-04-2017, 12:27 PM
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Default Cast vs ductile(nodular) vs billet flywheels

Building another blower motor 454 with a 6-71. Has a forged eagle internal balance crank and won't be spun past 5500 rpm. Should be around 600hp and 600 ft lbs. I have a cast flywheel but I'm wondering if I should step up to ductile iron(nodular) or billet.

Edit: Forgot to mention this is a standard bravo type application.

I thought the billet pieces were mostly for high rpm and I'm not sure if anything other than cast is necessary in a marine application where there is no clutch/shock loading.

Opinions?

Thanks,

Travis

Last edited by 89Force235; 12-04-2017 at 02:42 PM.
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Old 12-05-2017, 10:30 AM
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Travis

This is good question as I was also going through sorting out my flywheels and wasn't sure whether should run aluminium (10lb), or steel flywheel, as have one steel flywheel which is 13lb, 28lb and 30lb in weight
In fact got me thinking of actually using my trans-blanket previously used on power glide dragcar and adapting to mercruiser bell-housing for safety
You can never be too careful, I suppose it comes down to what gear you got lying around
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Old 12-05-2017, 10:50 AM
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Thanks for the reply. I don't know if a flywheel has ever exploded without the shock loading of a clutch and hard shifting but certainly don't want one going through my engine hatch or the bottom of my boat or worse... I ran a cast one at the same rpm and around 525 hp or so previously. It didn't occur to me that it could be an issue until I considered the new engine. Not really too concerned about the weight, if anything I'll stay heavy to help with shifting at idle.
I think this time around I will at the least I'll step up to the ductile(nodular).
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Old 12-05-2017, 01:20 PM
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I'm not so sure the rpm would be an issue as much as the heat is with cast. I've heard some horror stories over the years. Cast and hp and heat can be catastrophic. If your only dealing with one engine I'd consider spending the extra money to be on the safe side. Like you mentioned though most the bad day stories I've heard about where at the track and not marine. We've run stock 454/365 mag flywheels in blown applications pushing 700 hp without any issues.

Will be interesting to see what others have have to say. You can always search for a good used one at half the price or purchase a new one from 250-300 if your concerned. Cheap insurance policy. One thing I know for sure is I wouldn't wanna be in the back seat if one ever let go in a boat.
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Old 12-05-2017, 01:32 PM
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put a neutral balancer and steel flywheel on it and call it good
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Old 12-05-2017, 03:02 PM
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Also the cast flywheel you currently have I'm assuming is or you had neutrally balanced and same goes for balancer as f-2 mentioned. What gen 454 do you have? My ati flywheels are near 50 pds if I recall. Not a bad thing for marine but....
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Old 12-05-2017, 05:30 PM
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Quote:
Originally Posted by F-2 Speedy View Post
put a neutral balancer and steel flywheel on it and call it good
High jacking my own thread here but, flywheel aside. I was planning to run a crank hub. No balancer.
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Old 12-05-2017, 05:50 PM
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Quote:
Originally Posted by 89Force235 View Post
High jacking my own thread here but, flywheel aside. I was planning to run a crank hub. No balancer.
Please laugh (vs getting rubbed the wrong way) at this statement. That makes as much sense as buying a 1986 Hyundai Excell for your Significant other whom has along commute thru bad neighborhoods.
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Old 12-05-2017, 09:17 PM
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Btw there's some flywheels FS on swap shop.
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Old 12-06-2017, 09:28 AM
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i may be wrong but i think the gm bbc flywheels are nodular cast iron.
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