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Discussion Starter #1 (Edited)
My question is what horse power and RPMs can a cast crank safely handle in a BBC 454 four bolt main block?
I'm planning a 92 octane friendly compression , (2) 750 cfms on a tunnel ram, rect. port 990 heads, hyd or flat tappet cam in a v-drive. 5800 rpm max in a v-drive boat. Is a cast crank in a four bolt safe to 6000 rpms? Thanks for any info.
 

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Some guy
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My question is what horse power and RPMs can a cast crank safely handle in a BBC 454 four bolt main block?
I'm planning a 92 octane friendly compression , (2) 750 cfms on a tunnel ram, rect. port 990 heads, hyd or flat tappet cam in a v-drive. 5800 rpm max in a v-drive boat. Is a cast crank in a four bolt safe to 6000 rpms? Thanks for any info.
Is there a reason you don't just find and buy a good used GM steel crank, since you seem to have some other good parts? Shouldn't cost much in today's economy.
 

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Discussion Starter #4 (Edited)
It is a Chev cast crank. So the four bolt mains do not do anything for a cast crank shaft? I do not think my motor will be running above 6000. So as long as that rpm on occasions is safe I'm good with the cast crank.
right? Since I already have this set up in a motor I just got I'm trying to keep costs down.
 

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Frank my lord
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yep

You probably won't break it. But who's cast crank are you talking about? Just so you know, the four bolt isn't helping your crank live. You keep mentioning it like it makes a difference. It doesn't
im with you on this , 4 bolt block not going to make crank live longer with this type of build , cast cranks ive ran successfully all day long at around 500 hp and under 6500 rpm's and no problems , probably wouldnt push more than that but the biggest thing is to let oil temp get up before beating on it. ive seen more spun bearings because off the trailer and bam full throttle then wonder what just happened. like obnoxious001 said , forge be better.:)
 

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Discussion Starter #9
My 18" Flat Hondo has 15% gears, 11 1/2" x 15" two blade. I'm feeling my motor will probably not exceed 6000 rpms. BTW Con. rods have 3/8 stock bolts. Probably go with stronger ARP bolts there. Thanks for the input. If I stumble across a steel crank I will probably buy just it to feel good about everything in the motor.
 

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just a ski boat with bark
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My question is what horse power and RPMs can a cast crank safely handle in a BBC 454 four bolt main block?
I'm planning a 92 octane friendly compression , (2) 750 cfms on a tunnel ram, rect. port 990 heads, hyd or flat tappet cam in a v-drive. 5800 rpm max in a v-drive boat. Is a cast crank in a four bolt safe to 6000 rpms? Thanks for any info.
Well I'm probably going to get a lot of crap for this but in my experience if a good GM cast crank is turned .010"/.010" with nice radiuses they will live well beyond 6000rpm.

IMO, detonation is the #1 killer of cranks, then if you load and unload the prop that stresses the crank as well. With good machine work and some care in use and warming up before running hard they are better than most people give them credit for.
 

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Well I'm probably going to get a lot of crap for this but in my experience if a good GM cast crank is turned .010"/.010" with nice radiuses they will live well beyond 6000rpm.

IMO, detonation is the #1 killer of cranks, then if you load and unload the prop that stresses the crank as well. With good machine work and some care in use and warming up before running hard they are better than most people give them credit for.
I was starting to sweat on my set up, feel better now!:D
 
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I ran a cast crank in a jet turning 5800 for years. If I remember right, it was turned .020/.020. I polished the beams of the stock rods and installed ARP bolts. It made about 500 HP. Raced it 1 year in a hydro turning 6800. Never had a problem with it.

Tim
 

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just a ski boat with bark
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My 18" Flat Hondo has 15% gears, 11 1/2" x 15" two blade. I'm feeling my motor will probably not exceed 6000 rpms. BTW Con. rods have 3/8 stock bolts. Probably go with stronger ARP bolts there. Thanks for the input. If I stumble across a steel crank I will probably buy just it to feel good about everything in the motor.
Is this a true flat or a runner bottom?
 

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If you have done everything absolutly perfect, correctly and have a professional engine builder do it for you, it won't last. Now if you and a couple of friends and a 30 pack throw it together late friday night and then headed to the river right afterwords and ran the hell out of it all weekend, it will last forever! ;)
 

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AKA Blownjet 468
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If you have done everything absolutly perfect, correctly and have a professional engine builder do it for you, it won't last. Now if you and a couple of friends and a 30 pack throw it together late friday night and then headed to the river right afterwords and ran the hell out of it all weekend, it will last forever! ;)

OH so true! ALWAYS seems like the slap together junk parts/ ball-honed,
quickies are always the ones that run hard, and last forever!! but usually
those ones are never your own! :D
 

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I'm famous !
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If you have done everything absolutly perfect, correctly and have a professional engine builder do it for you, it won't last. Now if you and a couple of friends and a 30 pack throw it together late friday night and then headed to the river right afterwords and ran the hell out of it all weekend, it will last forever! ;)

I love those motors .. They don't pull like a probuilt but I love those engines :D
 

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If you have done everything absolutly perfect, correctly and have a professional engine builder do it for you, it won't last. Now if you and a couple of friends and a 30 pack throw it together late friday night and then headed to the river right afterwords and ran the hell out of it all weekend, it will last forever! ;)
The above can be sooooo true as > it took a Pro-Shop to fu*k up my line hone :|err
 
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