Aluminum alloys typically have 7% silicon in them. The alloy our block top half has , has been supersaturated to about 14%.Then the block was bored to size and lapped with an acidic silicon mix that will only remove the aluminum and leaves the very hard silicon standing proud. This eliminates sleeving. The cast iron rings then run on the silicon surface.
You could contact Porsche head office in TO or call sunnen the supplier of hones and silicon lapping compound. If you do it yourself wear a respirator mask as it causes cancer.
look here
http://www.precisionenginetech.com/p...icon-compound/
Wayne Strutt
waynestrutt@295.ca