how much HP can a stock forged 350 steel crank hold up to?

 

Well, i'll see at least

i plan to put the stock crank, rods (with some ARP bolts) and some cast 8.5:1 pistons through about 550hp-600hp by the end of summer

edit:

oops, i'm a moron. i saw stock but not the FORGED part

well now i'm confused......i dont know a thirdgen that came STOCK with a FORGED crank. They were all cast steel

what crank are you referring to?

 

Now im confused too, im getting my "stock steel" crank remachined and I was under the impression they were all forged. The guy at the machine shop said an Eagle 4340 forged crank was a little stronger, but not much. most of the other people i talked to said the same thing. They Cast Steel? isnt that what a Cast Crank is? or is that cast Iron? whoa somone inform me now... But mine isnt out of a thirdgen...

 

ok there are two 3 types of cranks

cast
foged
billet

cast is usually what is in most motors, cheap to make and produce.

forged is stronger and is usually aftermarket. These are your cranks that have the 4140, 4340, etc

billet is the strongest and takes the longest to make because it is made out of a solid piece of steel

that help?

 

Um yes and no. I knew there were 3 types of cranks mainly, but i guess the question now is did they ever make a CAST STEEL crank? you said yourself the 4130 4340 etc.. cranks are forged, and those numbers are steel numbers... So it doesnt make sense that the cast would be made from steel. I dont think you can CAST steel.. can you? is that the question? yes i think so Just taking a history lesson from you guys tonight. heh.
but i still think mines Forged Steel

 

None of our cars came with forged cranks all factory cranks are cast iron not cast steel none the less they are good to about 600 hp.

 

I will try to address this and those of you that catch the ones I miss or screwup can add your 2 cents. What kind of crank do I have? I hear this all the time. Mostly factory cranks are usually of the cast variety. What kind should I use in my buildup? Well this is what I have to say about crankshafts. Starting with factory cast cranks. There are two types of cast factory cranks to my knowledge, "Grey" cast iron, like your blocks or heads, and "Nodular" cast iron, which has a little alloy of some sort (nickel, I believe) to make it stronger (most late model engine blocks have a higher nickel content for same reason and exhibit awesome wear characteristics). A new catchword that we are hearing from Scat and Elgin and a few others is "cast steel" or 80-60-08 cast steel cranks. It is of similar material to forged cranks but it is not formed under tremendous pressures (taking a lot of metal and pressing it into something smaller and stronger). They just pour this steel into forms and add a little alloy change to make it harder. These are a step up from cast iron and will suit most performance needs for hot street cars and are successful in circle track. Cast Steel cranks offer a stronger than stock and lighter alternative to most forged cranks. But, be forewarned, I have seen lightweight rotating assemblies with these cast steel cranks that rev so freely that they broke the crank snout off from the inertial resistance of the weight of the harmonic balancer and accessory drives. I have also seen blower cars break the snout of these cranks. Let us now move on to forged. Starting with factory forgings. Factory forgings are usually found in some of the following engines; all 283's (3.00" and are all small journals), all Chevy 302's, small journal 327s (3.25"), some large journal 327's (3.25" have heard of and not seen), a few older 350's(3.48"), the LT4 350 (3.48" [1 piece late model rear main seal]), some 396-402 BBC (3.75"), never ever in any factory 400 SBC, some 427 BBB, and some 454 BBC. These cranks are forged using the same process as factory forged rods (except 7/16" bolt BBC) using a forged alloy called 1038 steel. I have seen many a small and big block Chevy using factory forged cranks where a race crank should have been up to 900 and 1000 hp. I do not recommend these power levels with a stock forging but it shows that you can get away with often. Factory forged cranks are also known for their lighter weight characteristics as far as forged cranks go. We next move to regular forged cranks and race cranks. Performance 4340 forged steel cranks, also known as Chromemoly, a lightweight extremely strong steel used to be as rare as buffalo nickels. Now they seem to abound everywhere. There are many manufacturers making and selling them in varying degrees of quality. From some manufacturers (like scat or cola) you can get everything from a base model big beefy model to a flyweight sprint car version ($$$$). Some are forged flat and then the journals are twisted into index while they are still hot while others are forged with these indexes (hence non-twist forging name) and amazingly some manufacturers will start with a forged block of 4340 and "whittle" it with a CNC machine, down into a little crank. These are the most expensive kind. All of this also all applies to the slightly stronger but heavier 5140 forged steel parts that are available lately. The one I am only slightly unsure of is this 4130 Chromemoly stuff. I understand it to be another alloy of Chromemoly. I have seen 4130 items that are both forged like cranks and rods and cast which is usually rocker arms, usually referred to as investment cast. Many performance pushrods are made of this are 4130 Chromemoly. I believe the new LS1 motors have 4130 investment cast rockers as an example. I hope this has cleared things up, and if it has created more questions, then good. I know I didnt just tell which crank to use but I tried to arm you for your decision about which type to use.

 

the crank is not from a third gen not sure what it came out of exactly got alot of motors torn apart from alot of diff cars but what i do know is that it is factory forged because of the wide lines where the crank was molded together. Cast cranks have a small thin line where the crank was molded together. Correct me if im wrong but i do believe thats an acurate way to tell

 

If you know the way they both look then you can and have indentified it properly.

 

well then mine must be a factory forged steel crank, since there is no molding line??? either way its a large journal 350 crank that came out, and im grinding it .010 / .010 to make it all smooth again and stop eating bearings. it will be used with a blower

 

maybe it is a $2800 cnc billet crank if it doesnt have a parting line, or a gremlin snuck into your crank case and ground it smooth while you were sleeping.

 

My Eagle 4130 crank has no visible parting line

 

yea im using my factory forged crank for a blower motor as well almost done after i buy rocker arms im puting blower on motor and will be done with it next week

 

what was I thinking of course your nice cranks dont have parting lines, they are fully machined, sorry about that

 

A forged crank will usually have a wide parting line (about 1/2-1") while a cast crank will have a thin parting line. You could grind it off to eliminate a stress riser.

A forged crank will ring bright if you tap it with a hammer, while a cast crank will have a dull "clink" sound.

HTH!

Andris, celebrating the last 30 minutes of his b-day