Crankshaft Comparison

[getchasum]

I was looking on FT website when I noticed quit a difference in the weights of these crankshafts. Originally I thought these cranks were the same Chinese forgings just machined by different companies weather that was Eagle, Cat, BA, etc. but evidently that is not the case. One crank almost double the weight.....

From a comparisons standpoint which is the better crank and why?

Or if there has already been a discussion on the subject could someone point me in the direction of that thread.

http://www.fullthrottlespeed.com/itemdesc.asp ic 172523136255967 eq Tp

http://www.fullthrottlespeed.com/itemdesc.asp ic 270StrokerCrank eq Tp

 

[forcefed3.8's]

85lbs doesn't sound right. The Eagle is 4140 steel, the GN1 is 4340.

 

[getchasum]

Even looking at the weights of the other GN1 cranks the weights are high. I weighed my BA stroker & it came in at 48 lbs

 

[Nick Micale]

The 85# figure is not correct, probably the finger hit the wrong key!

I just weighed a BMS stock stroke crank and it is 46#'s, and a GN1 3.625" stroke is 42#'s.

 

[turbo96max]

"The Eagle is 4140 steel, the GN1 is 4340"

hows quality on either one compared over a cast unit? and versus one another? is there a real benefit to the gn1 vs the eagle?

 

[bison]

4140 and 4340 are USA alloys. These cranks are forged over seas. Are we really sending our steel over seas for forgings? Maybe the Chinese equivalent of our alloys?


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[Mike T]

I may be crank shopping myself......subscribed. I hope the discussion will continue I see a lot of threads on here that could be very informative just die.

 

[Pronto]

Buy 10 and sell the rest!
http://www.alibaba.com/trade/search...tId=&SearchText=buick+forged+steel+crankshaft

 

[Mike T]

Buy 10 and sell the rest!
http://www.alibaba.com/trade/search?fsb=y&IndexArea=product_en&CatId=&SearchText=buick forged steel crankshaft

The link didn't go to the cranks but I've also heard that there are a couple of different companies over seas making these cranks and the quality differs....is this true or just more misinformation out there?

 

[delcowizzid]

same place you buy $35 forged h-beam rods

 

[Mike T]

same place you buy $35 forged h-beam rods

Good example. I have a set of the old K-1 rods that was purchase from a vendor probably 6-8 years ago. Around the time of the purchase I found rods online that looked identical to the K-1's (marketed under a different name) for far less. I asked my machinist about the other brand and he said they were absolute junk! So I wonder if much like the crankshafts the final machining is what's making one "brand" better than the other or are the forgings inferior ?

 

[Mike Licht]

In the case of the old K1 rods the machine work was done here is MI and the bolts were actually ARP. The current stuff is not machined here. We switched to Molnar to keep the quality up.
Mike

 

[Mike T]

This article is from 2010 and seems to be a fair assessment of the import cranks. It points out a lot of the little things you may find in the imports cranks but I'm sure most vendors have the tolerance issues figured out by now.

http://ezinearticles.com/?Imported-Buick-V6-Steel-Forged-Crankshaft-Replacement-Options&id=4580908


Also I thought this was interesting.....this photo appears to be a Chinese made Buick crank forging before machining. I found it on a Chinese companies web site that sells raw materials.

 

[turbo96max]

Can we assume that if our vendors are selling them they are ok? Like the eagle and gn1 pieces?

 

[Mike T]

Can we assume that if our vendors are selling them they are ok? Like the eagle and gn1 pieces?

This would probably be a good chance for some of the vendors to point out what sets their crank apart from the others. IE extra machine work done to take care of some of the little problems mentioned in the article.

I'm not sure how the Eagle crank starts life.....it may be a different forging and Mike would be in the best position to fill us in on that.

 

[Nick Micale]

This article is from 2010 and seems to be a fair assessment of the import cranks.......................

That was a "fair assessment" 5 years ago, but is not the case today.

Various companies are importing forged Buick V-6 cranks, and rarely do we find any issue with the quality or machining.

We have installed well over 100 of the China forged cranks and never had one that needed major machining, and recently they are a drop-in piece, but like ANY aftermarket part it must be checked out properly before installation.

Some of our engines with China cranks have produced up to 900 HP and we have yet to experience or hear of or see any crank structural failure?

Any forged crank is light-years ahead of the cast piece in strength and durability.

 

[Mike T]

A lot of guys are running 10's and even a few 9's on the stock crank without coming apart. Based on my own personal experience (with a not so powerful motor) that showed signs of odd bearing wear patterns and a small amount of cap to block fretting I would love to see what the center main bearings look like in some of these 10 second and beyond motors.

 

[Nick Micale]

I have heard that BS for years and for every stock crank that has run into the 9's and 10's, a whole lot more have been trashed at that level, but those are not published!

How did that stock crank work out for you?

 

[Jerryl]

From what I have read . . . . On the internet . .

The forged cranks sold today are not the weak link in a production block, regardless of where they are made.
The stock crank has been fast but I would not underestimate the knowledge of those who have. The average person (myself included) will not be able to do that very long, if at all.

The small market we try to operate in does not lend itself to many options, and therefore, price should not be the first priority.

If I had to guess . . . . I would say that the same pattern is used to produce all currently available forged cranks. The main differences (if any) will be in quality control of the material and mfg processes. Machine shop, assembly and tuning knowledge will ultimately the key to success.

 

[Mike T]

How did that stock crank work out for you?

I don't see mine living long.... at lets say another 100 HP or so. We do have a couple of club members who run anywhere from 10.60 to 10.20 on a stock cranks and I've not seen anything catastrophic happen with their cars yet. But as stated earlier I'd like to see how their caps and bearings have held up.