Honing the cylinders!

What is the correct paste to use when honing out the 928 cylinders and where do you get it?:confused:

denhamfly;10717 wrote: What is the correct paste to use when honing out the 928 cylinders and where do you get it?:confused:

My research and experience in the past is that the process is called lapping, and is different than honing. There are machine shops with the correct equipment.

I thought that after it is bored they acid wipe the bore to eat away the aluminum and leave a hard silicone face.

careful with the info over here guys.. Alusil is not a coating..it is the material that the block is made of (hypereutectic aluminum silicon..see the wiki en.wikipedia.org/wiki/Alusil ). Nicasil is a coating (nickel silicon) that can be used on an alusil bore and it is also rock hard.

The 928 block had special heaters in place during its formation to allow more silicon to be present in the bores of the block. Once it was set, it was bored and then a special machine/paste (sunnenhone machine ) was used to expose the silicon crystals in the face of the bore. This is what the pistons/rings ride on and its extremely hard and wear resistant. One can easily expect over 300000 miles from a 928 alusil block.

malcolm;10726 wrote: the block and bore is aluminium and as such cannot run a piston and ring without a coating such as Nikasil or Alusil (silicone as Porsche used).

If the block is bored the coating is gone and has to be 'replated'

If not bored it can be lightly 'touched' or recoated to correct spec.

If the spec's are good and you put new rings get in it and go?

If the bore isn't scratched or gouged then that is what I would do.

denhamfly;10730 wrote: If the spec are good and you put new rings get in it and go?