TheSamba.com :: View topic - SCAT 4340 Forged Crankshaft VS. DMS/DPR Crank

Sun Jul 20, 2014 7:15 pm

ok well if we have to be picky then yes all cranks are produced by morons because I've never had ONE that had the rod clearance come out correct.

GEX crank the gear area has runout, china crank the gear area is too small. Which one can be fixed???

I have a 76mm old bergmann, all welds mag'd good, I re-doweled and re-ground and straightened it and it has lived in the turbo buggy four years now. That sucker runs SMOOTH :shock:

Sun Jul 20, 2014 8:30 pm

I have a DMS 69mm counterweighted crank in my engine. It grenaded the previous engine it was in shortly after breakin (rod bearing froze and spun). Turns out one journal was ground too large. Not sure if it was done after it was originally counterweighted/8-doweled. We sent it to DPR for journal to be re-ground/polished, so far so good. YMMV, if you can't measure it well yourself find a machinist.

I also had a Chinese forged 82mm crank a while back that jingled like a bell, like there was a piece of steel loose in it. We removed all plugs but couldn't fish anything out, it did get successfully replaced though.

Stan

Sun Jul 20, 2014 9:13 pm

mark tucker wrote: the 3 welded cranks I have had my hands on all had issues,bad issues from the prosess,not from usage. one was a true work of art with fullcircle weights,it sure was purty...but it was shit as far as Im concerned as it was used but a big name builder.then came to me after about 800 miles....in a bunch of boxes.but the entire thing was a effing mess not just the crank,but it had welding& machining issues. the other two had machining issues too. I just dont see any reason to use one,none at all.but yes they work even the effed up ones worked....or did they???

You are right to mention - and blame - the crappy manufacturing by incompetent operators.

It's all stuff people should be aware of, and ask their crank supplier and/or engine builder about, when selecting/specifying a crank for a performance engine. Unfortunately, for a variety of reasons, a lot of this fundamental engine-building practise is overlooked these days, especially when beginners believe that a few hours of on-line browsing, and unverified statements/opinions from strangers, is considered 'research'.

At least with a VW OE-based cranks, if it checks-out through the proper inspection processes, you're starting with a known-quality good core.

A properly built crank - with CNC-cut counterweights, assembled/welded by professional welders, eight-dowelled, heat-treated, finish-machined, surface-treated/hardened, yadda, etc and dynamically balanced - can cop 9000rpm and more boost than is sensible :)

Sun Jul 20, 2014 10:07 pm

VWCOOL wrote: mark tucker wrote: the 3 welded cranks I have had my hands on all had issues,bad issues from the prosess,not from usage. one was a true work of art with fullcircle weights,it sure was purty...but it was shit as far as Im concerned as it was used but a big name builder.then came to me after about 800 miles....in a bunch of boxes.but the entire thing was a effing mess not just the crank,but it had welding& machining issues. the other two had machining issues too. I just dont see any reason to use one,none at all.but yes they work even the effed up ones worked....or did they???

You are right to mention - and blame - the crappy manufacturing by incompetent operators.

It's all stuff people should be aware of, and ask their crank supplier and/or engine builder about, when selecting/specifying a crank for a performance engine. Unfortunately, fro a variety of reasons, a lot of this fundamental engine-building practise is overlooked these days, especially when beginners believe that a few hours of on-line browsing, and unverified statements/opinions from strangers, is considered 'research'.

At least with a VW OE-based cranks, if it checks-out through the proper inspection processes, you're starting with a known-quality good core.

A properly built crank - with CNC-cut counterweights, assembled/welded by professional welders, eight-dowelled, heat-treated, finish-machined, surface-treated/hardened, yadda, etc and dynamically balanced - can cop 9000rpm and more boost than is sensible :)

Curious, who's welded crank would YOU recommend?

Sun Jul 20, 2014 10:27 pm

VWCOOL wrote: At least with a VW OE-based cranks, if it checks-out through the proper inspection processes, you're starting with a known-quality good core.

Are you? I don't know a single person on God's green Earth that can tell me the fatigue life a crank has left on it when it's been used, no matter what inspection or machine operations it's been subjected to. I've seen welded cranks last many thousands of miles, and I've seen one break the first weekend it was out. There's just no telling. At least with a new crank you start at 0 hours, so if the material is good quality and the work was done right it ought to last a lot longer than a welded crank.

When I bought my crank, I paid the extra $200 to have the nitriding done on it. You can do the same thing to any crankshaft, but again, what fatigue life are you starting out with on a used/welded one?

Sun Jul 20, 2014 11:27 pm

I’ve been stoked with the quality of my Scat crank and rods but not so surprised when you put those kind of dollars down. The crank webs are one of kind smooth to the bone. Ran the crank and rods in a daily 2110 for several years and the same set now in a 2276 both take fair amount of abuse and still chuggin along. But Scat gets zero points for their lube-a-lobe lifters that I found pitted when I stripped down the 2110.

Before building the 2276 I sent the crank to Bob at DMS to have a look over. He found it a tiny bit out of straightness and corrected it, magnafluxed, freshened up oil galley’s, and installed the gears. I remember him saying Scat sends him cranks to be wedge-mated to flywheels. Bob as you know likes to chat he mentioned the lawsuit against Scat for false advertising "made in usa" forged cranks and rods as we all know but said it's a small community and it all gets worked out. Would I buy a Scat crank again? Absolutely yes my first choice but I would definitely want to try the others mentioned, lots of good stuff out there.

Mon Jul 21, 2014 7:19 am

miniman82 wrote: VWCOOL wrote: At least with a VW OE-based cranks, if it checks-out through the proper inspection processes, you're starting with a known-quality good core.

Are you? I don't know a single person on God's green Earth that can tell me the fatigue life a crank has left on it when it's been used, no matter what inspection or machine operations it's been subjected to. I've seen welded cranks last many thousands of miles, and I've seen one break the first weekend it was out. There's just no telling. At least with a new crank you start at 0 hours, so if the material is good quality and the work was done right it ought to last a lot longer than a welded crank.

When I bought my crank, I paid the extra $200 to have the nitriding done on it. You can do the same thing to any crankshaft, but again, what fatigue life are you starting out with on a used/welded one?

You're mixing with the wrong crowd! A metallurgist, machinist - hell, even a high school teacher - will be able to explain fatigue thresholds. That's what makes a standard, forged VW crank from a stock 1600 engine such a good basis for a welded performance crank.

They have been operating below the threshold for fatigue.

If you've seen one of these break in the first weekend, it's because someone stuffed up - not due to the materials.

One of mine dates to 1985 and has done 100,000+ miles. It's outlived three cases and two sets of heads. That's what 's possible when it's done right, but do it wrong and ... well... bang

Mon Jul 21, 2014 8:36 am

I like the quality of my DPR ,, but I had a demelo before this one , I never ran it but the quality of just looking at it wasn't up to the DPR

Mon Jul 21, 2014 10:03 am

I just had a DMS 86mm chevy rod fullrace weight crankshaft built for one of my motors and it looks awesome. Great machine work and balance job. Funny when i was in there they showed me one of the other companies new welded stroker crankshaft and the neck where the gears went ran out alot! The mains were straight but once you put a dial indicator on the neck it did not run true with mains! You can polish a turd but in the end it is still a turd!

Mon Jul 21, 2014 10:26 am

I would always lean toward the DPR or DMS product but one thing Scat has going for it it is the oil groove and directional troughs. They can be added by DMS or DPR though.

Mon Jul 21, 2014 4:26 pm

If the material used is sub-standard, it will fail, no matter how awesome it looks to the untrained eye

If the processes used to make it are sub-standard, it will fail... no matter how awesome it looks to the untrained eye

And it seems a lot of cranks these days are badly made from poor material :(

Mon Jul 21, 2014 8:54 pm

so whats the deal with my snout run out???it was a german core..... the very first vw engine build I did I balanced the crank, well it was so soft I would not use it.Ive built a few hundrad engines and balanced more than that.Ive never seen any crank as soft as it.thus I dont have any vw cranks in any of my engines. I did buy the dpr stroker(because everybody said it was oh so much better than the china shit. well that cran has never been in an engine,too much runout for me. I understand every crank cant be perfect, but so far out of the 3 welded cranks I have had in my shop...well none was right. and out of the china cranks well the only issue I had was one had the groove too deep for the snapring.(scat). yes the welded cranks look great, and seem to proform very well.but for me, in my engines I want a new 1 peice 4340 crank. I have alsohad loose gear on vw crank.....it was the gear.jose pointed it out to me,I have him do my balance work since I nolonger have a balancer,he does awesome work.
So this thing about cranks is kinda a prefrance like everything else.so get what you are confident in. and hope for the best. but be sure to check every single checkable thing befor using any crank or any other part. these welded cranks have shown me a few extra things to be checked when checking a crankshaft.

Tue Jul 22, 2014 2:58 am

If a welded crank is not built right, it won't be right!!

At least you were able to measure-discover-reject the poorly-built cranks before they went into engines.

Many engine 'assemblers' can't/don't

Tue Jul 22, 2014 3:29 am

Once you get over about 78mm you can't really claim on the metallurgy or forging of the original German Core. Forging isn't rocket science, if you keep an eye on your manufacturers it can safely be done in China or South America. While the Chinese are in general lovely people, the people who own the factories are true capitalists, and will get away with anything they can.

Tue Jul 22, 2014 4:52 am

If you truly understand metallurgy and heat treatment you won't buy a welded stroker crank.

The Chinese make exactly what the vendor orders. If you want to pay for top quality the Chinese can make it. If you want the cheapest shit you can find the Chinese have no morrals and will cut corners to give you the crap you want in the cheapassed price range you are looking for.

Tue Jul 22, 2014 6:22 am

Understand that YOU are not the customer of the Chinese mfg. They do not care what you think. They care what the company buying from them thinks. They'll make what is requested, high quality high price, or low quality low price, and anything in between. People are fooling themselves thinking they are going to get high quality for a low price.

Tue Jul 22, 2014 6:58 am

You know... It's kind of funny when we start talking about price and quality of our parts then compare that cost to other engines. You can get 8 Scat H beam rods for $430 for a V8 but ours are in the $250-$300 range for 4. Our cranks are about $250 and up and so is a new V8 Scat Crank. Billet aluminum Roller rockers for a set of 16 is $250 and I paid over $450 for my 8 Pauters!
How is it that we can spend $10,000 on an engine and call any one cheap or any part Junk? I guess it goes to say what we all have said before. If the Chinese parts are junk then we should only pay junk prices. It's when people start perpetuating that all Chinese cranks are great because they say "4340" or "Billet" and what not, when they are not, that is what allows them to charge full price or double the price of what it's worth.
Makes me sick that we spend so much and can still call anything in our engines "cheap" or "junk".

Tue Jul 22, 2014 7:05 am

[email protected] wrote: Understand that YOU are not the customer of the Chinese mfg. They do not care what you think. They care what the company buying from them thinks. They'll make what is requested, high quality high price, or low quality low price, and anything in between. People are fooling themselves thinking they are going to get high quality for a low price.

i agree... anyone and everyone has to make a living..

if the vendor/company is stateside and a cheapA$$ it doesnt make the factory workers have any less morals.. theyd work the same if the product was of higher quality + expensive...

no way a more expensive product means they earn more per day.. thats just ignorant LOL

........................
on a sidenote
we run a china crank, it was slightly bent but checked ok with no cracks
straightend it.. then balanced the whole rotating assy.

1,137whp (note AT the wheels) on a 2liter 4cylinder inline 4 turbo motor

i think welded cranks are great... but if a 4340 crank can handle that much..

i think any street motor wont mind either crank...

shoddy builds just tend to be less tolerating on certain parts LOL

Tue Jul 22, 2014 7:30 am

So are Berg cranks in its own realm and pure USA made or do we have to be careful shopping there too?

Tue Jul 22, 2014 7:45 am

smkn_vw wrote: So are Berg cranks in its own realm and pure USA made or do we have to be careful shopping there too?

swedish forging machined in the u.s.a and NLA