Porsche, VW or Chevy journal, Whats the best?

[vwpride73]

Whats the best? I have the opportunity to buy a DPR crank with porsche journals. I've heard they were stronger than VW or Chevy journals.

[LouisB]

Rabbit journals all the way.

What stroke is the crank? Porsche journals are strong, but finding rods may be difficult and costly.

Louis B.

[Marc]

The difference is in what's left of the crank after the rod journal has been ground. Smaller journals (like the 2" Buick/Chev) have less overlap between the main journal and the rod journal so the crank will be weaker there. Big journals have more surface area (good) but the surface speed at the journal/bearing interface is higher (bad). The difference between stock VW and Porsche isn't dramatic and probably nothing to lose sleep over for a typical engine (how much power were you expecting to make, anyway?). DPR prefers to use non-crossdrilled 1500 cores for their welded strokers rather than cross-drilled 1600 cranks - they say they're significantly stronger - but sometimes they'll use a cross-drilled if that's the only core available. I'd consider that more important than the journal size for strength. The Porsche journal isn't as popular as it once was and there aren't too many choices for connecting rods; stock Porsche rods are a bit shorter than VW and yield a pretty low rod ratio when used with a stroked crank.

[Muffler Mike]

this is how i understand it.
Porsche Journal . skinnier then the vw journal allowing the crank to be bigger between the cheeks. But if its welded crank, the cheeks are already in place and havent been forged that way to begin with. (such as a berg crank)
plus the bearings are questionable in quality, and more expensive then a vw. the reason for this was to keep the journal diamter but make the crank cheeks wider.
VW journal same diamter as porshe but wider, leaving the standard width cheek, but also gives more rod to main journal overlap for less crank flex then a chevy journal crank may offer.
vw quality bearings ok, probablyy about the same as you can find in the porshe
chevy journal, same width, smaller diamter. helps with clearance. chevy is 2" vw and porshe 2.165"
Bearings found for this application cant be touched by a vw. but lack of rod to main journal overlap. So some will go with a bigger main, such as a type 4 center or all t4 mains to compensate on bigger cranks.

so depending on application, id stick with VW journal.

[george brown]

"All of the above". We are using Chev 2" rod journals and a type 4 center main journal Scat 86mm ultra-light crank in my 2,387 with the BMW adapter center main bearing.

The smaller rod journals allow for less case/cam clearancing problems; many people run Chev rod journal cranks in high output VW engines without problems.

If you want Porsche journals it's a good idea to buy aftermarket chrome-moly rods as the original Porsche rods are not as strong as they might be. One well known engine builder uses tight side clearances with Porsche rods (they have narrow big ends) and notches the sides for oil relief.

[vwpride73]

It's a specially made 82mm crank that was made for a dragster. I wanted to make between 170-200 hp with this engine.

[Chris Andrews]

this is how i understand it.
chevy is 2" vw and porshe 2.165".

OEM std VW is 55mm rod journal & Porsche 912 is 53mm in diameter.

[Muffler Mike]

So the porche jounal is 2.086"
learn somehting new every day.
thanks.

[bajaman73]

Hey all - Dug a crank outta the shed today. Looking for stuff to build a motor for my Bus and came across one stamped 82.. seems a date code stamp maybe just under that but smaller stamp 3 77
Also has 5558 X stamped one one side of crank and EPW 715.... and 4 85 B just under that on the other side of the crank.

Im measuring the mains at 2.165 and rods at 2.075

Any ideas what or where its from? Seems to be a stroker crank with porsche rods??

Thanks for any help