im building a 383 stroker, and ive got enough money to spend on a completely forged bottem end. thing is... someone i spoke to told me that if i wanted to race my car, it would be better to go with a steel crank and forged rods+pistons rather than forged crank+rods+pistons. does this make sense? i always thought a forged crank would be stronger than a steel crank, but he told me that the forged crank is hollow and the steel crank would be better for racing applications. someone set me straight here...lol

 

Forged cranks are certainly not hollow. How much power are you realistically expecting to make? A cast crank might be fine.

 

and btw... does anyone have any suggestions on a cam? i have dart ie 180's (im going to port them more to help the 383 breathe a little better) and im using the hsr manifold. my current cam now is the xr276hr, but im actually looking for a little bit more power than that... maybe the 290HR-12? any suggestions would be helpful. thanks guys

 

honestly? i dont know. i just want to be able to dip into the low 12's. everytime i try to build my car to a certain hp#, im always way off... so this time, im trying not to guess and just trying to build something worth building. 450hp to the crank would be nice... but i could just be dreaming lol

why do you think this guy would tell me that steel cranks are better than forged? i questioned him on that and he told me he's been building engines for 27 years and he knows what he's talking about. im not too sure though... i always thought forged was stronger than steel.

i was thinking about s/c the iroc, but now that i think about it, it's too much money. nitrous MIGHT be concidered if i ever decided to play with her after the new motor's put in, but im not 100% sure. im sure one day i'll want more power, so thats why im not crossing nitrous out. i want her to be all motor... for now i guess. maybe 100-150hp shot later on down the road.

 

A cast crank would be fine for 450 HP, but you could use a forged one if you want.

 

is that 450rwhp?

 

Flywheel

 

isn't forged more or less just highly pressure treated so to speak?

rather then just casting it into a mold they instead put it in a press and squish the hell out of it?

 

Something like that, i believe the compositions of the metal make it stronger too.

 

My old 383 had a stock 400 crank and rods. They didn't cause the failure. I either broke one of the factory rod bolts or destroyed a cast piston. The engine made an estimated 500 hp and was running mid to high 11's when I finally destroyed it.

Cast crank is the weakest since it's cast steel. Steel comes in different styles. Forged is just a term refering to a steel crank. They're offered in different strengths. 5140 and the stronger 4340. The other type of crank is a billet steel crank.

Spending the extra for 4340 engine parts in a non race engine is just overkill.

Alloy steels
1010 --Standard alloy steel, one step above nodular iron.

1053 --One strength-level better alloy, used in high-performance crankshafts.

5140 --Excellent alloy steel, a compromise between strength and price.

4150 --Much more durable alloy, yet not quite as strong as 4340 alloy.

4340 --Premium-grade alloy steel used for ultimate-performance cranks in both forgings and billet. Standard for aerospace and diesel industries.

 

So when i build my 383 w/ approx 500hp at the crank being just a street car a cast crank will be fine?

i would hate to be 1/2 way across canada and have my crank laying in the middle of the road

 

Hard to say unless you've had it magnafluxed lately to be sure there's no cracks. Providing you're not using any kind of power adder, it will probably survive but a cast crank could break at any time.

Daily driving isn't going to see too many WOT runs to the max rpm that you'll be getting 500 hp. Cruising down the highway might see 150-200 hp at the most depending on the speed.

 

just to be ****, the 1010, and other 10 series steels, are carbon steels, not technically alloy steels, as the 10 means just iron and carbon.
The last 2 digits are usually the % carbon, so 1010 is .10% carbon, 4340 is .4% carbon, etc.

Any lower then .25% carbon is considered "mild" steel. any higher then like .6% is like a tool steel. Higher carbon content makes the part less ductile, and more brittle....stronger, to a point)... Cast iron is "steel" but with over 4% carbon, so it's very brittle.


43 series is an alloy, containing iron, carbon, nickel, etc...

forged is indeed, just something that was cast, then beat the snot out of with giant presses...

if it's shaped when hot it's "hot rolled", cheap, and nasty finish.
if it's shaped after it cools, it's "cold rolled", more pricey, stronger (like being forged), and usually has a nicer finish.

billet is when they mold the part and compress it while it's cooling I think... Making it very shiny and strong... (I'm totally lost on that one...)

Whew, there, I finally got to use my mechanical engineering knowledge... knew that would come in handy sooner or later...

 

I am pretty sure billet is when the item is cut out of a larger piece (block). This makes it more consistent.

 

The billet itself is the large unworked slab of metal that the part is entirely machined out of.

 

Also, keep in mind that cast crank cracks show up at a rate of 1 for every 10 cracked forged cranks. More or less (according to vizard) this is due to the generally harder life of forged cranks, and cast cranks have a certain amount of "flex" or "ductileness" to them.

In other words, forged cranks are stonger, but more prone to fatigue than cast cranks. GM knows what they are doing when they research these things.

 

The current setup on my GF's car is a studded 2 bolt main, stock 89 crank, Lunati Pro Mod Rods (I got them for a steal) and wiseco pistons with 8:8:1 comp. Can I run 12lbs boost? Or is that pushing it?

 

I would go forged, or at least cast steel. (scat 9000 or equiv.)