[68WarDog]

At what power level do you go to an aftermarket crank versus a stock one?

[performerrpm]

ive bought 2 or 3 forged cranks for motors i hope to make 800hp or more with, the way i understand, the block will go before the crank.

[JSuchma]

I think 800 HP on a stock block without filling the water jackets with hard block is pushing the limit.

[steve25]

Aftermarket forged only , don’t even think about a cast one because the factory cranks are better.

[prostreet64]

The factory N nodular iron cranks were pretty stout. I would think 500-600 hp would be no problem.

[b-man]

If between 5 and 6 hundred horsepower I’d be considering a forged crank.

Looking at what it costs to properly prep a stock crank you’re already about halfway there anyway.

[68WarDog]

Originally Posted by steve25

Aftermarket forged only , don’t even think about a cast one because the factory cranks are better.

Steve, that's my thinking too. Over the past 30+ years I've only used Nodular cranks, except the P. Dude prep ones.. Not sure of "regular" cranks limitation..The engine builder just texted me, my crank is std/std, it's a 73 455 crank, non-N. The engine should be in the low 500 hp range, and possibly a little more in torque. The cam is a bullet hydraulic roller with HLJ hydraulic roller lifters with pin oiling. Cam specs are 234/[email protected]. Lift. 580. 455(462)/forged rods/ forged pistons.
.

[blueghoast]

Close to 650 hp and 300 shot on factory crank and block for years
no problem just a lot of fun.
Thats not to say you can't break it but there pretty darn tuff.

GT

[performerrpm]

i tbought all the 455 cranks were N cranks. as far back as i can recall, even on these forums...stock N cranks was always better than aftermarket cast cranks. the aftermarket cast cranks won out on longer strokes at affordable cost...that said, until the first 450.00 forged cranks came out it was pretty common to read threads about guys spinning stock cranks close to 7k with good rods/pistons and in the 6-700hp range. id think 500hp would be nothing for your std crank

[Joe's Garage]

Of course, it's spinning with Carrillo rods and Brooks 13:1 pistons.

Never been near a dyno, but the online ET to HP calculators say it's making between 550 and 560HP.

So I also believe the factory 'N' cranks are pretty tough.

Of course, our IAII 541 has a forged 4.5" crank in it..........but it's still on the stand........

[steve25]

Any one have Jim Hands book to post up how much abuse a 455 crank took that he has fail that he talks about?

I will do so later if no one else does, but the amount of time it took of getting beat on was astounding before it gave out!

With lighter reciprocal parts getting use in builds these days I would say 650 is where I would draw the line in being very safe as long as your not planning to race the motor every weekend for 2 seasons.

Prepping the crank ( polishing the crap out of it) will make a huge difference in longevity as will cryogenic treatment if theres a location close enough to drive it to.

Tuning for no detonation I am considering a given.

The SD455 acording to the engineer who designed it was made to run day and night at 6000 rpm with a good margin of safety, and these motors left the the factory with a cast crank, so just putting that out there.

[i82much]

so how much stronger is a $700 aftermarket forging vs a factory N?

[srmmmm]

Originally Posted by steve25

With lighter reciprocal parts getting use in builds these days I would say 650 is where I would draw the line in being very safe as long as your not planning to race the motor every weekend for 2 seasons.

Prepping the crank ( polishing the crap out of it) will make a huge difference in longevity

.

This was my thinking in my build as well. With an Eagle cast 4.25" crank in my 350 block, I'm not at the extreme power levels discussed. But feel confident in it's durability at my 453HP because of the lighter pistons. And as you mentioned, I did have the crank polished as an extra measure.

[JLMounce]

Using the factory N crank in my 455 build. Did 580/600 on the dyno. The build is too new to discuss real longevity yet, but so far so good.

Nothing crazy on the machining. The shop magged it, checked it for cracks and polished it. The crank was already 10/10, but did not need to go 20/20. Touched up the line bore and using a quality BHJ harmonic balancer. I have no concerns about this setup as it's not a race car that sees hard passes its entire life.

[PAUL K]

Originally Posted by blueghoast

Close to 650 hp and 300 shot on factory crank and block for years
no problem just a lot of fun.
Thats not to say you can't break it but there pretty darn tuff.

GT

This

[steve25]

Here’s the service life that Jim Hands got out of a 455 crank.

135,000 miles before it came out of the donor car.

2500 mid to low 12 second passes.

8 years of hard street driving in 4000 lb car.

Almost 2 years in 12 second nitrous powered 77 Can Am.

Could anyone really expect more?

Close examination of the pictures of the failed crank from his book look to me like it failed at internal sharp edges left by the factory drilling of the oil passage at there junction point.

[Formulas]

Internal oil passages .... One time i ran a straight flute carbide reamer through a 455 crankshaft's oil holes not expecting to do very much i was very suprized at the amount of cutting debris ... and the reamer was same nominal size

[steve25]

I always run a long drill bit through the oil holes in all my cranks after hot tanking, and yes the crap that comes out many times had to make for some level of flow restriction.

[hurryinhoosier62]

Originally Posted by 68WarDog

Steve, that's my thinking too. Over the past 30+ years I've only used Nodular cranks, except the P. Dude prep ones.. Not sure of "regular" cranks limitation..The engine builder just texted me, my crank is std/std, it's a 73 455 crank, non-N. The engine should be in the low 500 hp range, and possibly a little more in torque. The cam is a bullet hydraulic roller with HLJ hydraulic roller lifters with pin oiling. Cam specs are 234/[email protected]. Lift. 580. 455(462)/forged rods/ forged pistons.
.

‘73 should still be a nodular crank, whether it’s marked or not.

[hurryinhoosier62]

Originally Posted by PAUL K

This

All boils down to proper prep, assembly and tuning.