I believe they are cast as Aluminum Silicon alloy all the way through.

From all of the folks that I have spoken with, yes. Hypereutechtic (sp?) T-390 alloy. Alloy=all the way through.

yeah, but aren't they etched to make the surface mostly si?

I think that if you treat the freshly board out cylinders with one of the proven methods described in this thread then you would get the desired finish.

This thread has given me confidence to re-ring my Alusils but I have a question for the experts on the list. Goetze part number 08-320900-10 interchanges to both of the Porsche OE numbers for Nikasil/Alusil. But the factory spec book say the groove 3 piston rings for are different. For Nikasil "bevelled edge oil control ring with hose covered spring, not chrome plated." For Alusil "double bevelled oil control ring with hose covered spring, chrome plated." Is this a meaningful difference?

Hi zzwhm. I started this thread (what seems a lifetime ago!) and my Goetze rings are still going strong. I work for Goetze so had lots of help from our engineers at the time.. I've prob covered around 8-10000 miles since, and if I had to make the same decision again, I'd do the same...

I still have my alusil cylinders out for 'honing'. Then "ll send them back to Adam R for re-measuring the surface roughness. I'm embarrassed about how long this is taking.

Nathan M -
Thanks for the update. I plan to use Goetze and am glad to know that they are working great for you and so many others. But when I saw the difference in the Nikasil and Alusil oil rings described in the the Porsche spec book it made me wonder if it is meaningful. Maybe one of your engineers could comment on this?
Bill

They'd already confirmed they are suitable for both...

Yes, alusil cylinders are consistent all the way through the part. KS has another product - tradename, Lokasil - which is alloy all the way through but has a different mix of silicon localized at the cylinders.

Yes, you can overbore alusil cylinders, as William pointed out the problem lies in sourcing pistons. To be suitable the skirts need to be tin and iron plated. An engineer at KS suggested that perhaps graphite might work but hadn't tried. For 95 mm cylinders he said 98 mm was max overbore, any larger and the cylinder walls become too thin. Not sure what the max size would be for a 2.7. Best method is to overbore to another (alusil) stock or readily available replacement size if possible. Or you could find a plating company to treat JEs. The specs for the plating are in the thread.

I'm amazed this thread is still going strong. For those who haven't yet, please scan through it. There's a LOT, I mean really, tons of good info, hard work and research in here. Not to mention a little drama.

Well, I hate to report that after about 10,000 miles my engine outlasted the car. I wrecked it in November. The engine will be transplanted into an new test vehicle for further abuse! (Hopefully my brother's 73.5 longhood targa!)

My condolences. I am glad that you are seemingly ok.

Thanks, and this is am oppertunity. Next project is an 81 with a 3.6 conversion.

Measuring cylinders with electron microscope - only on Pelican!
 

What's the status on this? Not trying to get you to do anything, just curious if I missed it.
-Chris

I sent the cylinder back a few months ago.

Did you scan anything with the electron micorscope?
-Chris

I sent the cylinder for 'polishing' weeks ago. He keeps telling me it will be 'a few more days'. It will get done.

I will when I get it back. The EM can't see inside a cylinder, so I must break it up first. Those suckers are tough.

What has been the experiences of re-ringed alusil and the different honing methods. someone out there should have a few miles built up.
Thanks in advance

My cylinder is ready for pick-up. Within a few days I will mail it to Rondinone for examination. I can't believe how long this took...