Nikasil alusil good for block why not good for pistons?
 

Nikasil coat an Alusil block and you can use third party aluminum pistons, so why wouldn't Nikasil coating the pistons and leaving the block Alusil also work?

Sooner or later I hope some kind of coating other than factory works.

the idea is that the piston rings to cylinder wall is where the friction is, not piston to cylinder wall per se......

if you coat the cylinder walls, you kill two bids with one stone.

if you only coat the pistons, you leave the rings to wreak havoc on the aluminum cylinder walls.

The same rings are used for Alusil and Nikasil aren't they?

Or just use whatever rings the block needs?

different rings for alusil vs nikasil, mostly because when a block is nikasil'd it has the honing marks in it to bed the rings in like most domestic cars....

You have no way to finish the piston like you do to the block. Blocks are diamond honed after plating...there is no good way to finish the Nikasil plating if it was applied to the piston. it is rather rough once plating is through and woudl then have to be final cut on the piston. There are other piston coatings that allow the aftermarket piston to be run on Alusil...Swain makes one and so do a coupel of others including JE.

All older engines end up out of round anyway, so it is best when you are rebuilding to get a new cylinder surface via Niaksil.

I still have a 1984 block from a Callaway car which was sleeved...this is a survivor!!!

Yes, I had that discussion with Charles Navarro. He does Alusil to Nickie stuff for the air cooled crowd. No way to finish the pistons to size.

I wonder if anybody has tried? or tried very hard?

OTOH with DLC and other coatings maybe its a moot point?