Resurfacing aulsil bores in a 944
 

I have done a lot of research on resurfacing the bores on these cars. I would suggest everyone read this post on pelican http://forums.pelicanparts.com/911-e...g-alusils.html There is a lot of black magic and people that try to make assumptions on what is the best way to resurface the bores and although for the most part any attempt to resurface is probably better than nothing there is a correct way to do it and it's not that hard. Sunnen is an American company and they pioneered the Alusil process in the "60s if you call them they will gladly help explain how to do it correctly (as explained in the Porsche factory manual). I had to buy a Sunnen hone and two different sets of stones as well as the lapping pads and the paste and cutting oil. the only way to resurface the bores is to lightly cut away the broken silica and embedded carbon and metal particles that are in the aluminum. This was shown in the Pelican article under an electron microscope. The AN-30 is NEVER to be "cut" with mineral oil it kills its ability to remove the aluminum and expose the silica correctly. Call Sunnen tech support, read the Pelican article.

Link is not working..

Can you link to AN-90, Ive never seen it mentioned anywhere, only AN-30.

I have cut AN-30 with very light mineral oil (used for instrument oiling) and it came out good. Pure paste is too thick for handheld tool.

Try this


http://forums.pelicanparts.com/911-e...g-alusils.html

The silica paste is AN- 30 not 90. Sorry I was going by another post.

I would think to do this work correctly, it would have to be done on a proper honing machine. Doing it with a drill couldn't possibly give you the needed consistency and ability to adjust the pressure from one end of the bore as required. I used a CK10 machine once at a community college machining course and quickly decided it's the only way to fly.

Definitely better to use proper machine but hand drill will also do the job and it is consistent.

Check out pictures of my cylinder which was bored for 0.5mm then polised to final size. I did the AN-30 at home with drill and surface changed from shiny to matte dull very consistent.

Left cyl after AN-30, totally different than right that wasn't yet treated on this pic. Look at the reflection.

https://cimg3.ibsrv.net/gimg/rennlis...bc488242da.jpg

All done.

https://cimg4.ibsrv.net/gimg/rennlis...9a666e5db0.jpg