VipZ28

iTrader: (4)

Which would be the stronger piece? A brand new GM crank or a Seasoned one? i'm asking because my stock crank has 73K on it, never had any problems with it, so provided it checks out OK when pulling it, would it be better to use the seasoned crank or a new crank for a 382 all bore build up?

Colonel

Either is fine. No sense replacing a piece that there's nothing wrong with.

VipZ28

iTrader: (4)

I know they would both be fine peices, My question was more of one just from the inquisitive side, which would be stronger, the seasoned one or the new one? Personally I think the seasoned one that has been "heat cycled" a few times would be <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" />

Colonel

How hot does a crank get while being constantly bathed in relatively cool oil? Not very. I don't think that will make much, if any, difference.

Colonel

I think a more important factor is stress. A crank is constantly flexing. I would think this flexing would tend to weaken the crank somewhat over time.

VipZ28

iTrader: (4)

Cranks get warm, the oil isn't THAT cool <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" /> 200 degrees is about where the temperature will sit with the crank, as for the flex, FLEX IS BAD, If a standard crank moves at all it would be moving aroud in the oil ring between the steel and the bearing, if your crank is flexing it needs replacing. I was thinking back to some of the old skewl racers, They preffered seasoned parts if possible, they seemed to last longer than new parts. Any engine builders care to chirp in? <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" />

Colonel

200 degrees is pretty cool in the context of heat treating metal.

ALL cranks flex constantly (I didn't say alot). It's impossible for them not to.

VipZ28

iTrader: (4)

It's more of a deflection than a flex though. Flex sounds like alot of movement to me <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" /> And thats why "heat cycles" was in quotes <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" />

<small>[ November 13, 2002, 11:09 AM: Message edited by: VipZ28 ]</small>

Colonel

Ok, deflection, flex, just a difference in terms. So they deflect if you'd rather. <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" />

Colonel

Hey just for fun let's get picky about our terminology...

de·flect [ di flékt ] (past de·flect·ed, past participle de·flect·ed, present participle de·flect·ing, 3rd person present singular de·flects)
verb

1. transitive and intransitive verb change course: to change course because of hitting something, or change something’s course by coming into contact with it The pitcher’s arm deflected the ball into the outfield.

The word "deflect" doesn't seem to suggest any bending taking place. Are we talking about a change of course here or some slight bending of the crankshaft taking place? I think it's the latter.

flex [ fleks ]
verb (past flexed, past participle flexed, present participle flex·ing, 3rd person present singular flex·es)

2. intransitive verb bend: to bend or be able to be bent The board flexes as you step on it.

<small>[ November 13, 2002, 11:17 AM: Message edited by: Colonel ]</small>

xaon

iTrader: (12)

hahahaha. I think he got you blane <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" />

Kris

VipZ28

iTrader: (4)

<pulls on suspender straps> well i'm no fancy lawyer, but it seems to mean that differences in wording is a common misunderstanding between different regions. However... yeah he got me <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" /> We just consider flex to be different amounts of movement. However, I think I'll use my old crank anyways <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" /> <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" /> <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" />

Colonel

<img border="0" title="" alt="[Razz]" src="gr_tounge.gif" />

All in good fun. <img border="0" title="" alt="[Wink]" src="gr_images/icons/wink.gif" />

Tin Indian

"Old School Racers" prefer seasoned parts to new....

Your right, but they are talking seasoned blocks when talking about seasoned parts.

Never heard of any talk about seasoned crankshafts in the 25 years I have been playing around with engines and so forth. If givin the choice, I would prefer a new crank to an old one that has big miles on it (newly machined or not).

Hey, I might be wrong... Just sharing this with you.

Ron,

________________________________________________

<small>[ November 15, 2002, 05:39 AM: Message edited by: Kimchee and Rice ]</small>

LS1derfull

Ron you are right , pieces like the block, when seasoned will make more power than new item because its machine work will stay more round and flat than new "green" block. Cranks do flex and surface of metal fractures from this which in turn can lead to failure. RPM duration history and magnaflux are best way to determine usefullness of used crank for your new build up. <img border="0" title="" alt="[Wink]" src="gr_images/icons/wink.gif" />

Tin Indian

magnaflux

Thats whats its all about!

In aviation, we used to call it 'Non-Distructive Inspection' (NDI)

<img border="0" title="" alt="[Smile]" src="gr_stretch.gif" />

VipZ28

iTrader: (4)

heheh RPM Duration huh? In that case I'll be getting a new one <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" /> In one year I've put 25,000 miles on it, and I'd say ATLEAST 1,000 of that was WOT and thats a VERY conservative number... 30 track passes, as well as atelast onw blast each time I drive it... hmmm... ok, 2500 miles at WOT then <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" />

J-Rod

NDT (Non destructive testing) MagnaFlux, Mag Particle, Eddy Current, Xyglow, Dyglow, X-Ray and Gamma Ray... My dad has been a NDT technician and then an inspector his whole life, along with my Uncle. So I grew up around that stuff.

Anyhow, about seasoned versus green. Here is the deal. People wanted seasoned blocks. This was beacause it usually took several heat cycles to get past any core shift, etc.. That would take place. Also metal act differently once it has been seasoned a bit.

Now, casting technology has come a long way so it isn't as critical. But, to really sason a god part, you can cryo it. That is better than any seasoning process you can come up with. That will stabilize the metal. It will be stronger, and it will machine much better.

As for cranks, since they bend and stress, their heat cycling isn't as critical as the fac that they haven't been abused. An Ls1 crank seems like a fairly strong piece for mild street duty.

When racing small blocks I have friends who have used cast 400 cranks for many years in 9 second cars. They replace the crank every 50-100 passes. They'd run aluminum rods to soften the shock to the crank.

Your crank should be fine up until about 500hp after that you might consider a forged piece. Most shops could mag the crank for you if you are wooried, but I wouldn't unless you feel you have a reason to woory. Most good shops can clean the crank and do a visual on the crank and give you a good idea of if it is ok or not. LS1s to the best of my knowledge aren't prone to cracking like some other cranks out there.

Reckless

iTrader: (9)

Ahhhhhh....the "Colonel gets ****" thread <img border="0" title="" alt="[Wink]" src="gr_images/icons/wink.gif" />

Ron...don't you have some beer to drink, some cig's to smoke, and some girls to chase <img border="0" title="" alt="[Wink]" src="gr_images/icons/wink.gif" />

Todd

J-Rod

Cranks don't deflect. They bend. Look at any inline 6 crank. Its bent plain and simple. You put it up in a press and your straigten it out. Most SBC cranks don't tend to bend though. But some do. Although you do get bent cranks through a machine shop fairly regularly, I see them all the time. The shorter the crank the less chance it has to bend.

Cranks normally fail due to excessive torsional (twisting) loads. The biggest place for this to happen is at the radius. on a journal. GM sought to keep this from happening so they hydraulically "roll" the filet. This makes a much stronger point on the crank. One of the biggest issues with remanufactured cranks is a shop that doesn't put enough radius on the journal. Production shop in many cases just dress the wheel on their grinder to keep it flat. They do that a few times and destroy the radius on each side of the stone. They don't go back and dress the corners to put the radius back in. When they get into the corner of the journal they cut it at almost a 90^ angle with a sharp transition. Stress risers start here, and the crank breaks. On a race motor often you can make a crank stronger by putting an even more generous radius in the filet on the crank and clearancing the bearings a bit...

<small>[ November 15, 2002, 02:54 PM: Message edited by: J-Rod ]</small>