Stage II crankshaft value?

[Squid4life]

Well, I am trying to decide whether I want to part with or hang onto the two cranks I have. Both are 3.625 stroke, both STD/STD, fresh from wetmag and polish. One is a BMS that has been knife edged, the other is a Crower. Contemplated using the BMS and stashing the Crower, but I still need to buy rods and pistons, so the $ would help. Both are used but nice shape. Crower has a bugger mark on one counterbalance due to a Carrillo giving up the ghost.

Any ideas on the value of each or either of these? Seems good cranks are getting hard to come by...

 

[750H.P.V6]

I'll give you $50 each.

Neal

 

[Squid4life]

Now that is crazy talk... The Crower is worth at least $70! Sheesh...

 

[odell4o8]

Neal, i was thinking around 80. bucks
serious they are worth whatever you can get for them,
good luck, oc,,

 

[Duke]

Will they fit the 109 block

 

[turbodaniel]

I JUST BOUGHT A SLIGHTLY USED (DYNO TIME ) CROWER FROM DUTTWEILER FOR $1900 ...FIGURED I SAVED $900 JUST MY 2CENTS

 

[J-B Racing]

You never ask " What is it worth"............I will give $49.95 for the Crower..Canadian Money with that New $100 Plastic Bill....Shinks in the Dryer...lol

 

[Squid4life]

You quoted it yourself:

"Any ideas on the value of each or either of these?"


How much is each crankshaft worth?

 

[Alky V6]

The BMS crank is most likely a forged crank. Do you know whether the Crower is a billet or a forging?

 

[Squid4life]

99% sure the Crower is billet. I thought all Buick V6 cranks from them were billet?

 

[Alky V6]

99% sure the Crower is billet. I thought all Buick V6 cranks from them were billet?

I didn't know for sure. I would consider the billet worth more than the forged. I would also want to use the billet before the forged in a serious engine.

 

[750H.P.V6]

Don,

I know there are conflicting opinions about which configuration is stronger. In theory it should be the forged crank due to the fact that the grain structure follows the shape of the part. The billet crank is machined from one piece of stock where the grain all runs in 1 direction. Why would the billet crank be better than a forged crank in a serious engine?

Neal

 

[Mike E]

It has to do with the quality of the material between when the bms forgings were made and now.

Current high quality billet parts are sometimes made from VAR (vacuum arc remelted) steel billets. They are, as the name implies, melted and cooled in a vacuum. This keeps pockets of gas and other impurities from getting trapped in the steel. No inclusions means no places for cracks to form. If VAR was around back when bms cranks were forged, it was probably a NASA only thing. Even now, it's tough to get VAR material. I can't say whether crower uses that material for billets or not, maybe they use plain old aircraft quality 4340. Even that is going to have less inclusions than 4340 of 20 years ago.

Today a high quality forging can also be made from this VAR material. That would be the ultimate in strength. I doubt the china made forged cranks use this high quality steel. You can also get billet cranks made fron EN30B or 300m material which is a stronger than 4340, but they might cost as much as a small house.

If money was no object I would have a billet also.

 

[Alky V6]

Don,

I know there are conflicting opinions about which configuration is stronger. In theory it should be the forged crank due to the fact that the grain structure follows the shape of the part. The billet crank is machined from one piece of stock where the grain all runs in 1 direction. Why would the billet crank be better than a forged crank in a serious engine?

Neal

Almost all the reading that I've done on the subject has always put billets at the top of the list. Almost all. The vast majority have favored billet.
Grain direction does seem to be the argument for those that favor forged. The sheer bulk of a crankshaft pretty much negates the concern of grain direction. If talking about a part that is lightened to structural limits, then forged would seem to have the advantage.
Mike brings up some good points as to quality of the material at the start of the different processes and the integrity of the processes to keep the grain structure sound. I have no clue when it comes to those areas.

 

[turbobitt]

I've had this debate many times with no particular preference on taking sides. The general conclusion is that a forging will be stronger. One of my friends, also a TB member, worked for Cummins Engine company and had some impressive pictures of a crank X-section showing the grain structure. Based on our debate, he had asked there engineers and they all agree a forging is stronger.

Crower will tell you that Top Fuel crnaks are sold both ways. Some use forged, some use billet.

In my opinion, it all comes down to the quality of the raw steel being used. Many variables is raw stock.

Allan G.

 

[750H.P.V6]

Mike is right in terms of material but I was actually speaking about the difference between forged and billet parts all things being the same. Having worked in and around turbine engine manufacturing and repair I can tell you that all our compressor wheels and turbine disks are machined from forgings not billet.

In my mind billet and forged cranks are equal in quality. Billet cranks are typically nicer finished parts due to the fact that every surface has to be finished where most forgings aren't. I would take either a good quality forged crank or a billet and use it for a foundation for a serious engine.

Neal

 

[Mike E]

If only someone could find the old bms forging dies. They could make forgings from new material and we could have some really great cranks. But they might still cost as much as a billet and its hard to say how much stronger they would be.

The other option would be to buy the good 4340 here and have it forged in china then finished in the US.

 

[Alky V6]

Mike is right in terms of material but I was actually speaking about the difference between forged and billet parts all things being the same. Having worked in and around turbine engine manufacturing and repair I can tell you that all our compressor wheels and turbine disks are machined from forgings not billet.

In my mind billet and forged cranks are equal in quality. Billet cranks are typically nicer finished parts due to the fact that every surface has to be finished where most forgings aren't. I would take either a good quality forged crank or a billet and use it for a foundation for a serious engine.

Neal

A turbine engine would be a perfect example of where a component must be lightened to specific structural limits. And, I'm sure the process of creating a forged part for a turbine engine is very carefully controlled and inspected. Materials and processes.
I'm not so sure that sort of care is also taken in the aftermarket manufacturing of an automotive crankshaft. It would be nice to find out that it was.

 

[49-blues]

I ll trade you a brand new set of JE pistons for the BMS crank- they re 4.00" bore for a 3.625" crank and 6.5" rods-in fact i ll throw in a set of 6.5" carillo rods in the deal?

 

[Squid4life]

I assume you are talking about used Carrillos?

49, that is a tempting offer, but I am going to stick with my original plan of a shorter rod, taller piston for street survivability.