Cast Steel or Forged Crank?

1785 Views 8 Replies 7 Participants Last post by sbc1320, Aug 16, 2012

gg63

Discussion Starter · Aug 13, 2012

I've been researching putting together a 406. Choosing a crankshaft seems to be more complicated these days. Most manufacturers seem reluctant to provide horsepower ratings on their products. Clearly a forged crank would be ideal but on a budget its seems out of reach or at the very least a long ways away. Will a quality cast steel crankshaft hold up to 400 plus (sub 500) horsepower in a hard driven street car with an occasional trip to the strip?

Secondly, internal or external balance? In general it seems easier to balance internally. I would like to use 5.7 rods but 6.0's are possibility as well. Will using an internally balanced crank require block clearancing?

Some real world experience would be appreciated.

Thanks in advance!

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PldBryan

· #2 · Aug 13, 2012

Well, I think you have answered your own question for the most part.

Yes a good cast crank will hold up to a 400hp build assuming that it is put together correctly, has a good balance job etc. It just comes down to how long it will last and how much over 400hp you want to go now and in the future.

I would not hesitate to build a 400hp motor with a good cast crank. If I thought I wanted to bump it close to 500hp or more down the road, I would start saving more money for a forged assembly.

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gg63

Discussion Starter · #3 · Aug 15, 2012

Thanks for the response. I think its going to be in that borderline range. I wanted someone to agree with my line of thinking so I could feel better about buying a cast crank.

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novanutcase

· #4 · Aug 15, 2012

I agree with Pld. If you're not going to be beating on the car EVERY day or putting it into a race environment you should be fine with a cast crank.

NOW....if you even remotely think that you may run more HP through the engine then forged for sure.

John

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rusty63ss

· #5 · Aug 15, 2012

JMHO is you should get the best parts you can even if that means you are going to have to wait awhile to build it. It is better to overbuild than underbuild. Who knows? You might get bored with it and decide to add a 150+ NO2 shot. Then you will be glad you spent the extra $$ when you built it.:yes:

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gg63

Discussion Starter · #6 · Aug 16, 2012

Thanks guys

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bowtie0069

· #7 · Aug 16, 2012

I ran a cast 400 crank for a long time; lots of nitrous, detonation (14.5-1 compression on pump gas) went across the country etc...And before I got the engine it was a dyno mule that has countless hours of abuse. It still checks good, and if I had an extra block, I'd use it again. Car ran 9's with it.
Mains are still standard size after 40 years.

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Vin63

· #8 · Aug 16, 2012 (Edited)

With some careful machining and paying attention to your tune, you might be surprised how much a cast or nodular crank can withstand. You would probably see a connecting rod-related failure before a crank failure anyway.

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sbc1320

· #9 · Aug 16, 2012

I built my 383 with a Scat 9000 cast crank, Scat I beam rods with 7/16" ARP rod bolts and those rods are rated to 750 hp. I estimate my engine to be around 520 hp.

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