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Thu Nov 13, 2008 12:19 pm

Is it the consesus that the old-fashioned welded vw cranks with welded on counter weights are superior to the modern 4340 forged Chinese cranks? Are the Chinese cranks pretty much all from the same source? :x

I've got a DPR welded crank in my Ghia and it has given no problems.

At least one article I've read and some discussions I've had with builders suggest that a welded crank is the way to go when building a turbo motor. I am thinking about a future turbo build and am wondering which way to go.

Any comments?

Thu Nov 13, 2008 12:29 pm

The problem is a bad chinese crankshaft gets the same price as a good one. To QC something to a spec would raise the price on them. The stock german one met some specs to start off with.

Thu Nov 13, 2008 12:35 pm

At this particular moment in time, if I was buying any crank 78mm or under, I'd buy welded from DPR or Demello. It's all about perception, and right now, I believe the original german forging is of better quality than the chinese one. Will the Chinese get better, yes. Right now their quality seems to be hit or miss. The $64,000 question is, will the people who sell chinese cranks step up and demand a higher level of quality from the manufacturer? As it stands now, cheap rules, because there are far more people out there (sellers and buyers) to whom a good deal matters most. I believe the Chinese, with the proper guidance, can produce cranks that come close to the benchmark - Gene Berg quality. Will someone forego a bigger profit margin to provide a true quality crankshaft? Only time will tell.

Thu Nov 13, 2008 1:44 pm

Jeff Pyzyk wrote: Is it the consesus that the old-fashioned welded vw cranks with welded on counter weights are superior to the modern 4340 forged Chinese cranks? Are the Chinese cranks pretty much all from the same source? :x

I've got a DPR welded crank in my Ghia and it has given no problems.

At least one article I've read and some discussions I've had with builders suggest that a welded crank is the way to go when building a turbo motor. I am thinking about a future turbo build and am wondering which way to go.

Any comments?

If your happy with DPR why not get the crank from them? Or :?: Billet crankshafts are at the top end of the high-performance crankshaft scale. A billet crank starts as a solid chunk of high-grade steel bar (typically 4340 material), and then everything that doesn't look like a crankshaft is whittled away through a series of machining processes. The advantage of billet is primarily in the grain structure. The rolled bar that forms the billet has a uniform longitudinal grain structure. In forging, the crank throws are literally pounded, pressed, and twisted in the dies, mashing the metal into the rough shape of the crank. The brutality of this process adversely affects the grain structure of the metal. In a billet crank, the grain structure of the original bar isn't distorted, and remains much more uniform and intact.

Thu Nov 13, 2008 2:14 pm

???

A forged one piece as a grain structure that flows within the piece. One machined out of one piece billet will be cross cut against the grain flow at journal points. I always thought the forged one piece was stronger. Is this wrong?

Thu Nov 13, 2008 2:15 pm

It was my understanding that a properly forged crank will have the grain wrapping around the corners
and be stronger than a billet where the grain must end at a corner from one direction or the other?

Ace, we must have been typing at the same time and had the same thought.

Thu Nov 13, 2008 2:51 pm

Don't mind Terry, he doesn't know so he's cutting and pasting again.
http://www.carcraft.com/techarticles/116_0308_crankshafts_how_to/index1.html

Thu Nov 13, 2008 2:52 pm

Thu Nov 13, 2008 2:55 pm

Thu Nov 13, 2008 2:56 pm

That's a PC way to say 'old and senile'.

Thu Nov 13, 2008 3:01 pm

miniman82 wrote: Don't mind Terry, he doesn't know so he's cutting and pasting again.
http://www.carcraft.com/techarticles/116_0308_crankshafts_how_to/index1.html

They write better than me. What kind of crankshaft do you have. Will Berg work on it :lol: They will work on my crankshaft :lol: 84MM Okrassa. When you buy a crankshaft see who will work on it.

Thu Nov 13, 2008 3:07 pm

Thu Nov 13, 2008 3:19 pm

Terry Cloyd wrote: What kind of crankshaft do you have, will Berg work on it?

What the hell does that have to do with anything? My crank isn't broken or in need of machine work, and even if it were, Berg is the last place I'd have work on it.

Terry Cloyd wrote: They will work on my crankshaft

Do you want a cookie, or something?

Terry Cloyd wrote: When you buy a crankshaft see who will work on it.

Anyone I damn well pay to work on it, that's who. If they don't want my money, that's their business. There are multitudes of local shops where I'm at that will grind a crank, I'm not hurting.

Thu Nov 13, 2008 3:23 pm

Thu Nov 13, 2008 3:33 pm

manxracer1 wrote: Well on second thought you'll be OK, you need to make HP to break one !!!

200 is enough for me, I'm too irresponsible to have any more. Not that I couldn't, I'm only at 10 lbs right now, headed for 18. 8) I'm not getting involved in a china vs US arguement, you can have that one.

Thu Nov 13, 2008 3:56 pm

Standards and process determine quality, not statements.

Thu Nov 13, 2008 6:00 pm

Terry Cloyd wrote: Billet crankshafts are at the top end of the high-performance crankshaft scale. A billet crank starts as a solid chunk of high-grade steel bar (typically 4340 material), and then everything that doesn't look like a crankshaft is whittled away through a series of machining processes. The advantage of billet is primarily in the grain structure. The rolled bar that forms the billet has a uniform longitudinal grain structure. In forging, the crank throws are literally pounded, pressed, and twisted in the dies, mashing the metal into the rough shape of the crank. The brutality of this process adversely affects the grain structure of the metal. In a billet crank, the grain structure of the original bar isn't distorted, and remains much more uniform and intact.

Terry,

At first I wondered why everyone was always picking on you. Now I understand why.

Terry, get your head out of your butt!

Machining a billet cuts through the grain structure and WEAKENS it! On the other hand, starting with a high quality billet and beating it into submission allows those grain structures to form around the various bends and curves and maintains the high strength because the grain structure has NOT been cut through.

Likewise, the forging needs to be forged very closely to the finished size to maintain strength. If you try to use one forging size and machine it to produce different stroke crankshafts, you will cut through the grain structure and weaken it.

Just because a crankshaft has been forged, doesn't mean that it can't easily be screwed up during the machining process.

Scott Novak

Thu Nov 13, 2008 6:14 pm

manxracer1 wrote: I just replaced my Berg 88MM crank when the rear flywheel dowel area snaped off.
Was this an early nitrided crankshaft or a later non-nitrided Berg crankshaft?

Scott Novak

Thu Nov 13, 2008 6:54 pm

Ace wrote: ???

A forged one piece as a grain structure that flows within the piece. One machined out of one piece billet will be cross cut against the grain flow at journal points. I always thought the forged one piece was stronger. Is this wrong?

Alexander_Monday wrote: It was my understanding that a properly forged crank will have the grain wrapping around the corners
and be stronger than a billet where the grain must end at a corner from one direction or the other?

Ace, we must have been typing at the same time and had the same thought.

Why are Moldex Cranks Billet? Why is Scat retooling their line of Forged One Piece Flanged Cranks to be Billet? Why is Marty Staggs, one of the leaders in extreme high end turbo race engines, offering a line of Billet Cranks? Marty has pictures of the solid round Billets that the cranks are machined out of like Terry mentioned.

http://www.thesamba.com/vw/classifieds/detail.php?id=586688

Billet Cranks are the top of the food chain.

As for the Chinese vs. Welded Cranks, both are good. DPR, and Demello are the ones making the stroker cranks out of stock VW Forgings, so yes, their quality control is probably a little bit better. On the other hand, companies like CB, EMPI, and Bugpack probably have made/sell a considerable amount more cranks than DPR, and Demello do. Anything mass produced in large quantities has the oportunity for defects to slip through the cracks. There is another post in the Performance/Engines/Racing forum praising the Chinese cranks. I have only actually witnessed one Chinese Crank from Scat that wasn't up to par. All others from Scat, Bugpack, CB, and EMPI have been spot on. I would think the one piece forging of the Chinese Cranks would be stronger than the crank that has a consderable amount of its stroke/journal added on by welding, but I'm no metallurgist.

Thu Nov 13, 2008 7:08 pm

"Anything mass produced in large quantities has the oportunity for defects to slip through the cracks."

Bet you the Germans had a whole lot less defects than the Chinese.

"I would think the one piece forging of the Chinese Cranks would be stronger than the crank that has a consderable amount of its stroke/journal added on by welding, but I'm no metallurgist."

That's why I stated "if I was buying any crank 78mm or under, I'd buy welded". :)