Horsepower/rpm limit for stock, cast 454 GM crank.

[machine shop tom]

I'm in the planning stages of building a 454 for a 4x4 truck. What would reasonable limits for horsepower and rpms for the cast, externally-balanced crank? He's looking to make 500-550 HP, revving not more than 5500-6000 rpms.

I'm leaning toward a 4360 Scat or Eagle (yep, I know the caveats on the Eagles)..............

tom

[Ron Miller]

That 454 cast crank is allot stronger than most people give credit. I have personally built several cast crank 454's using up to 200 shot of Nos and spinning them past 7000's r.p.m with no issues. What will kill a cast crank is any thing over 13.1 compression ratio and detonation. Just about any of the fast running Super Stockers with a 454 combo are using cast cranks and will spin them past 8000's r.p.m with no problems. A local well know engine builder close to me that builds boat/off shore 454's changed to cast cranks. The steel cranks were cracking. His ideas about cast cranks will flex a little and are more for giving than a steel crank. Grind the crank to .020/.020 and make sure you have the largest radius the crank grinder will give you. Gas Nitriding will help also with surface harding. Call Moldex and ask for Little Joe.

[67RS502]

my budget 502 has a factory cast crank,
626hp@6200
spin it to 6800
has seen 7200
never torn apart
I'd say around 600hp and 6500rpm should
live forever... or so.

[new engine builder]

That 454 cast crank is allot stronger than most people give credit. I have personally built several cast crank 454's using up to 200 shot of Nos and spinning them past 7000's r.p.m with no issues. What will kill a cast crank is any thing over 13.1 compression ratio and detonation. Just about any of the fast running Super Stockers with a 454 combo are using cast cranks and will spin them past 8000's r.p.m with no problems. A local well know engine builder close to me that builds boat/off shore 454's changed to cast cranks. The steel cranks were cracking. His ideas about cast cranks will flex a little and are more for giving than a steel crank. Grind the crank to .020/.020 and make sure you have the largest radius the crank grinder will give you. Gas Nitriding will help also with surface harding. Call Moldex and ask for Little Joe.

I am not trying to be a smart a-- but can someone try and explain to me why you could put a 200 shot of N20 on a cast 454 crank but anything over 13.1 comp. ratio will kill a cast crank???
Does a hi-compression ie. 13 to 1 comp. ratio or more "load" a crankshaft differently than a 200 shot of N20??

[jeff swisher]

Read more closely 13 to 1 and Detonation= death
When i read it i saw 13to 1, and you know how fast a brain works ,and then there was skepticism (spelling) then i saw the Detonation that followed...

You will be surprised how much squeeze you can get by with using stock parts.
You must have the tune spot on , and it will work for a long time without breakage

[new engine builder]

Read more closely 13 to 1 and Detonation= death
When i read it i saw 13to 1, and you know how fast a brain works ,and then there was skepticism (spelling) then i saw the Detonation that followed...

You will be surprised how much squeeze you can get by with using stock parts.
You must have the tune spot on , and it will work for a long time without breakage

I would guess at any comp. ratio detonation would = death.
200 shot on a cast crank??
Please stop, you are starting to scare me.

[CNC BLOCKS]

Years and years ago we tried to run stock cranks 2442 and they seem to show cranks in them plus the phasing and the strokes we off and to get them correct the cranks would end up .020 under on the rods.

Then we tried the Scat cast cranks about 10 years ago and those never lasted as we broke 4 in one season Circle track 370 horse) in the same spot and a shop near found the same results with the Scat cast cranks.

Since then we have gone to 4340 cranks and some 5140 cranks and no issus and they have a 1/8 inch radius and the indexing seems to be beeter then the stock cast cranks, The Compstar cranks seem to be a great buy for the money indexing is right on the money.

Tom here is a link to look over I just found.
http://www.chevelles.com/forums/showthread.php?t=244660

[machine shop tom]

Thanks for the good information and link, guys. I'll file the information for future use.

I called the guy to give him the info and the price on a set-up I came up with to give him the build he was looking for.

He called back and told me to cancel the job because he was going to order a "489 stroker kit from Summit".

It's probably the same kit at the same price I quoted him at the very start when he brought in his peanut port 454 and said he wanted 600 HP our of it a couple of weeks ago.......



tom

[CNC BLOCKS]

Thanks for the good information and link, guys. I'll file the information for future use.

I called the guy to give him the info and the price on a set-up I came up with to give him the build he was looking for.

He called back and told me to cancel the job because he was going to order a "489 stroker kit from Summit".

It's probably the same kit at the same price I quoted him at the very start when he brought in his peanut port 454 and said he wanted 600 HP our of it a couple of weeks ago.......



tom

He will be back I am sure

[machine shop tom]

Thanks for the good information and link, guys. I'll file the information for future use.

I called the guy to give him the info and the price on a set-up I came up with to give him the build he was looking for.

He called back and told me to cancel the job because he was going to order a "489 stroker kit from Summit".

It's probably the same kit at the same price I quoted him at the very start when he brought in his peanut port 454 and said he wanted 600 HP our of it a couple of weeks ago.......



tom

He will be back I am sure

Yup. He called and asked if I were working Saturday so he could check out to see if he was ordering the right thing........

Sheesh!

tom

[Keith Morganstein]

His ideas about cast cranks will flex a little and are more for giving than a steel crank.

This builders ideas are incorrect.

The forged steel crank has much higher fatigue resistance and will withstand more flex for a longer period.

There are limits to anything including a well designed and produced steel crank. A good steel crank is not an answer for all problems either , flex it enough and it will eventually fatigue and break.

A lower quality, less well designed steel crank with stress raisers or inclusions, poor heat treating will crack sooner of course.

[defrag010]

Keith beat me to it about steel vs. cast and flexing. I've actually found this out the hard way by ruining customers cast cranks when trying to straighten them before a grind. Try to put a cast crank in a straightening press and use the hydraulic ram on it.. you won't get very far till it will just snap at the low rod throw's fillet. A steel crank, you can stick it in and bend the thing all over the place. When anyone brought in a cast crank that needed to be welded and straightened (or had spun bad and gotten hot on the journals and warped it bad), I told them that there is a 50/50 chance the crank will break depending on how much it warps with the heat, and if it's beyond the limit of fillet peening it back straight (usually about .050" or less) I won't even attempt it.

[n2omike]

I heard Bob Glidden quoted saying that a cast crank will make more horsepower than a forged unit.

[new engine builder]

I heard Bob Glidden quoted saying that a cast crank will make more horsepower than a forged unit.

Are we trying to be funny???

[CNC BLOCKS]

I heard Bob Glidden quoted saying that a cast crank will make more horsepower than a forged unit.

With the torsional twist you get with a cast crank over a good forged crank I find it hard for that statement to be true, and most cast cranks are out of phase and the indexing seems to off, HMMMMM