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Posted by: stugray Apr 22 2018, 10:47 AM

I am looking for a good 2.0L stock crank (71mm).

It is for my race engine, so I would rather have forged than billet (like the SCAT product).

Who has used a AA forged crank? Any issues?
Do we know if these are brand new or reconditioned to be "new"?

Anything to worry about or better options?

https://aapistons.com/products/counterweighted-crankshaft-type-iv-vw-porsche-914?utm_medium=cpc&utm_source=googlepla&cmp_id=204697570&adg_id=16306239610&kwd=&device=c&gclid=CjwKCAjwwuvWBRBZEiwALXqjw2O1RIftUWYZRNqgOoSeoJ8U5Cxk_v-1meKW5UjzA1PORK-H_YLOqxoCrTYQAvD_BwE

Posted by: Mark Henry Apr 22 2018, 11:40 AM

They are OK but softer than a german crank.
Two schools of thought with racing, a non-counterweight crank spins up faster vs a counter weighted crank is smoother, longer bearing life, especially with a lightened flywheel.

What I would do is stick with a german crank, might get the german crank counter weighted. A german crank is stronger, less flex and harder journals than an AA (any china) crank.
Then do a full engine balance to +/- 1g, whole assembly fan, crank, fly and PP plus rods end to end.

I don't know what's available for a stock crank but H beam rods are almost 200g lighter than the heavy 2.0 rods.

Posted by: aggiezig Apr 22 2018, 10:40 PM

In my 2056 rebuild, I bought a DRD Racing Heads 4340 Forged C/W crank. It was expensive but supposed to be great quality. However, when searching just now for a link, I was redirected to EMPI.... I'm guessing DRD was bought out.

DPR machine shop is a good source to look for a german c/w crank. They take OE cores and weld / machine them to spec. Great reputation for quality work

Posted by: wndsrfr Apr 23 2018, 05:21 AM

Check out FAT....they have new forged 80mm cranks from a supplier they've used for ten years or more. For my 2316 they paired it with the flywheel & put in five dowel pins!

Posted by: Mark Henry Apr 23 2018, 05:42 AM

Pretty sure the new cranks are all the same manufacturer, or at least the raw forging is.

Posted by: zig-n-zag Apr 25 2018, 01:21 AM

A 66mm crank can be made into a 71mm crank by offset grinding the rod journals.

Posted by: mgphoto Apr 25 2018, 09:16 AM

39K miles on the 71 mm crankshaft from AA Pistons, no issues so far.
DRD sold his tooling to EMPI and closed up shop.
He did good work, I have a set of his heads.

Posted by: stugray Apr 25 2018, 01:44 PM

I was wondering if I could have a 1.8L crank ground down to a 2.0L crank. If the people doing the work can add a little weld to the outside of the journals you should be able to.

I have TWO 1.8L cranks (paperweights) on my shelf.

Posted by: mgphoto Apr 25 2018, 03:30 PM

1.7 and 1.8 both 66 mm same crank.

Posted by: Mueller Apr 25 2018, 03:39 PM

No need to add material. The new journal has a smaller diameter and will have an axis further away from the crank centerline for the longer stroke.

Posted by: Mark Henry Apr 26 2018, 10:34 AM

I personally wouldn't do this, to do it right it would need to be rough cut, stress relieved, green ground, heat treated and final ground to size. I may have missed some steps, one may be re-drilling oil holes for the rods.

If you add the work costs up it's way cheaper to find the correct core in the first place.

Posted by: aggiezig Apr 26 2018, 10:47 AM

Companies like DPR are doing exactly that

http://dprmachine.com/products/crankshafts-type-iv/

Posted by: gothspeed Apr 26 2018, 11:56 AM

Need to confirm but I believe that is what the factory did to achieve the 71 mm 2.0 stroke. Used the same forging then shaved additional material off the inside of the rod journals. This made the 2.0 crank journals a tad smaller diameter.

Posted by: Mark Henry Apr 26 2018, 12:12 PM

My crank is a welded Raby/DPR 78.4mm with type 1 rod journals.

Back several years ago Jake stopped using DPR due to quality issues, mostly because they used some in his mind questionable cores.
The core you send in to them will not be the same core you get back.

Would I still use them over a new china crank? Likely, but I'd carefully inspect the crank or pay a shop to do this.

Posted by: Mueller Apr 26 2018, 12:32 PM

This might help, or it might confuse

Posted by: Mark Henry Apr 26 2018, 12:44 PM

So that's ballpark .175" off of one side, I guarantee you are through the heat treating.
996 cranks don't even have enough heat treating to cut them 1st under.

In layman's terms the crank journal heat treat could be described as an eggshell. Very hard surface but softer underneath.

Posted by: gothspeed Apr 26 2018, 06:42 PM

It is my understanding that cranks can be stress relieved and re-heat treated. Such as is done when crank journals are cut for undersize bearings.

Posted by: wndsrfr Apr 26 2018, 07:37 PM

Gotta add my experience with 80mm cranks on my 2316 before I went with the FAT new forging one. Two failures....probably attributable to poor quality control in buildup welding and also the stress cracks from oil holes ending up too close to the web.
here's the links:
http://www.914world.com/bbs2/index.php?showtopic=162641&hl=
http://www.914world.com/bbs2/index.php?showtopic=197901&hl=

Posted by: Mark Henry Apr 26 2018, 09:23 PM

I have a 78mm here that's a paperweight. I don't know who did the crank.

I also have a 996 paperweight.
Be thankful you're not having that bad luck with a 996, around $1500 for a good used crank. About $30k for a new engine.
I can do them cheaper with a shortblock from Porsche, but still bloody expensive.
M96/97 engines are keeping me busy.