Engine Boring/Rebuilding

chally72 · 03-11-2011, 06:15 AM

What shops are available in the New England area that work with 944's/alusil boring extensively? I need an engine bored/possibly short block assembled, and was wondering what reputable local options I had.

Thanks.

MarkRobinson · 03-11-2011, 07:00 AM

locally: possibly none. I have a racer-buddy who has a full season on a 3.0 951T making 350/400rw: block & pistons prepared by Lindsay If I'm not mistaken, JE pistons, etc.

Mark

chally72 · 03-11-2011, 09:41 AM

Thanks Mark. Lindsey was the first and last option on my initial list for rebuild services.

By the way, this is why I need a shop. This motor had 2000 miles on a fresh rebuild by myself with re-ringing, new main,rod,balance shaft bearings, etc etc. I have no idea why the cylinders scored in the lower rear half like they did. I'm not comfortable doing it again myself without knowing what I f***ed up so bad in the first place.

chally72 · 03-11-2011, 09:42 AM

HondaDustR · 03-11-2011, 10:44 AM

Just out of curiosity, were the cylinders re-ringed as they were, or were they prepared in any way to break in new rings?

chally72 · 03-11-2011, 10:47 AM

Just re-ringed. I forget what the cylinder wear was, I might have it in my build/problem thread somewhere. The entire assembly was VERY clean when it went together, and the rings all checked fine. No hanging burrs anywhere on pistons, either, obviously.

HondaDustR · 11:02 AM

Alusil isn't that simple. Re-ringing used cylinders is a crapshoot at best. The shiny smooth surface of worn in Alusil cylinders does not have the abrasiveness to break in rings. Sort of like the crosshatch pattern honed into iron blocks, which holds oil, but also gives the cylinder some roughness to break in rings. That is why after boring, honing, and polishing at the factory, they lap with AN-30 to lap away the aluminum from around the silicone particles suspended in the alloy to form a very hard surface that is also slightly rough initially in order to wear in the rings. This roughness only lasts 30 miles or so, which is why break in is critical for fresh rings/cyls on these. With use, the silicone particles smooth out, yielding a very durable, smooth surface that still has microscopic spaces between the particles to retain oil.

Some people, myself included, have successfully "cheated" with otherwise good cylinders by doing a quick hone with scotchbrite pads, followed by AN-30 with felt pads. I have no idea if your failure can be attributed to new rings on used cylinders, though. What a bummer! I'm sure it can come good with a shop working on it, though.

chally72 · 03-11-2011, 11:03 AM

I did a real light job with scotchbrite and ATF in all cylinders, did not use AN-30. Lesson learned? Hard to say. The fact that it toasted only that portion of each cylinder is puzzling.

HondaDustR · 03-11-2011, 11:11 AM

I heard some of the 911 guys used just scotchbrite. The cylinders are likely not perfectly round since they are used, meaning new rings could have pressure points on parts of the cylinder. Did they measure up out of round at all, by you or by a shop? How do the pistons look? Is the iron coating still intact? The iron coating is very important, since aluminum has a very high affinity for itself and the aluminum piston material could have gotten exposed and begun tearing up the cylinders. How deep is the scouring? Did you scotchbrite by hand or use a 3 arm hone?

chally72 · 03-11-2011, 11:17 AM

Used a 4-arm hone that my father uses to do harley cylinders. Pistons were not out of round, checked on a CMM by myself. I didn't see any signs of galling on the pistons when I had them out, although they probably don't look too pretty now.

HondaDustR · 11:24 AM

Pistons were not out of round, but how about the cylinders? It will be interestingg to see how the pistons look and if you can tell if the iron coating has been compromised due to the scouring, or if the scouring was caused by the iron coating failing somehow.

Those marks remind me of this thread. http://forums.pelicanparts.com/porsche-924-944-968-technical-forum/582148-2-7-944-oversize-pistons-picture.html

chally72 · 03-11-2011, 11:24 AM

No, cylinders were not either. Checked with a bore-gage. Don't mean to have this discussion in 2 threads, by the way. This one got a little sidetracked.

AA_Ezra · 03-11-2011, 11:42 AM

I would call up a dealer. or better yet a privet dealer/mechanic and ask them were they get that type of work done it. Or possibly call up a race shop or a race track if you have one and do the same

I called about 20 different places no joke to get my flywheel balanced and to find out if anybody would press some rivets in my fidanza flywheel. Ended up being a Aircraft shop of all places.

VINMAN · 03-11-2011, 12:00 PM

Some marine shops that deal with outboards should have some experience with Alusil, or snowmobile shops also.

minho78 · minho78's Garage

Chally you have Chris White in Upstate NY. This guy has a ton of experience with our cars and building 3.0's. He has a couple of video about different engines he built on youtube.

www.944enhancement.com