Dave W.

Yes I had my crank nitrided. I can't show the full radius since the crank is still in the car. The pics are showing up for me, but it's a photobucket upload, so who knows how it really works this week. I uploaded two pics directly from my laptop, so those should show up for everyone.

F3ARED

Bit of a thread dredge from the depths, hopefully the guys that have played with this are still around. After discussing engine options with an older hot rodder at work, went down the rabbit hole and found the "sids hybrid" recipe and have been doing a bit of research since. This hypothetical will all center around an early 2.5L SOHC 8V block; this is a non-negotiable point as this is what I have available to me. Sourcing a replacement is not an option due to the limited availability in Aus and cost of obtaining another block would make this whole excersize a non-starter, at which point I may aswell continue with my 1.8T swap or look at paying the premium for 8V internals and keeping it at 2.5L. Unfortunately the costs tend to escalate here once you factor in exchange rate,shipping and import duties - we get ripped off every which way from Sunday down here. The biggest attraction to this is the Chev 350 bits and 4G63 stuff can be had locally, cheap, without needing freight and duties.....you can see why it got my attention.

After reading through the thread, the main question I have surrounds the differences between the early and later 8V NA blocks; there was a comment there about the wall thickness between early blocks and later blocks being different. Does anyone here know what that difference is, and how much walls are left once factoring in an overbore to 4.030"? I could go down to a 4" bore but at the moment struggling to find something off the shelf and readily available that has a 4" bore, enough -cc and a compression height of 1.425" to keep everything happy. I could obviously order it, but that would push costs back up to the point where id be better off looking at just ordering Wossners in the correct size from Lindsey Racing.

The other question I have is related to grout filling the block; is there anything precluding me from dowelling or pinning the block instead? Like someone else pointed out, its a pretty common mod in the Subaru world without any negatives.

N-

blade7

With 2.5 blocks my understanding is, it's only the very early turbo blocks that had the thicker walls. I seem to remember they have a different part number too. Offset grinding the crank is where it could go wrong, that has to be done by a shop that knows what they're doing. And a race shop guy I used to know, said hacking lumps off the big ends was a no no. Probably not an issue on the road or track days though.

944 timbo

I think the block filler has been used with good sucess, and I would point you to https://Refresh591.com/StrokerDIY.htm for more info.
For lightening the crank I would agree with Blade's comment. Although I have no personal experience with crank work, I did recently learn a bunch from watching this David Vizard video :
www.youtube.com/watch?v=14q5xp1epCY