n Alusil: The engine block is fashioned from high-silicon content aluminum alloy. The block undergoes initial machining, then, similar to Nikasil, is dipped in an acidic bath that etches away the aluminum on the bore surfaces, exposing the durable-wearing silicon.

Again, however, there are considerable problems. Alusil blocks must be made in a slow, low-pressure process, says Mr. Sach, and the original alloy itself is more expensive. He believes Alusil is good for low-volume use where cost and manufacturing speed are not the priorities.

Alusil's cost might be bearable even for mainstream vehicles, but a foreign automaker engineer insists, "Throughput time is not acceptable for high-volume lines. We would never consider this process."

n Lokasil: Promoted largely by casting-kahuna Kolbenschimdt Pierburg AG, Lokasil is a "sacrificial" bore liner comprised of silicon fibers in a binding that, when inserted into the block mold, burns out the fibers, leaving the high-content silicon surface directly in the bores.

The Lokasil process is acutely effective. But it also is laborious - slow squeeze-casting is required - and expensive. Currently, Kolbenschmidt's sole customer for the process is Porsche AG.