mark kibort

No one mentioned the number one reason to sleeve a porsche 944 motor. Its alusil gentlemen!
it cant be "honed" to fix any issues with the bores, it needs special process that not many engine builders can do.
its a very hard surface, and when working well, it will last a long time. it has a very hard surface, so hard, rings dont need to break in and there is generally no wear to the cylinders at all.
if you dont use a porsche piston, you have to go aftermarket. there is no credible coating supplier to coat the aftermarket pistons . so, the choices are few. nicasil it (best choice for piston options, but tricky for ring choice, and a pain to do the coating process) or sleeve it.
its that simple.
Mk

Charles A. Toupin

^ this too.

c.

Mike S.

Please explain Mark. I understand Nikasil is on the aluminum cylinder walls. Is it on the (Porsche) aluminum pistons too? Thanks. Mike

mark kibort

with nicasil, there is flexibilty on the pistons. basically, anything goes, but the ring package is very critical. Its a coating on the entire engine and then the cylinders are polished out.

alusil requires an iron coatng on the skirts mainly, and only mahle and a couple of other OE pistons have it. doing yourself or having someone do it usualy ends up with a engine that is gone in a 1000 street miles or sooner. some have worked, but very few.. alusil is the engine block, and the cylinders are treated via something that looks like a honer, but is not. it uses a special paste to wear away the aluminum and leave the slicon in the metal compound. alusil is not a coating, its what the the block is. (17% slicon in the alumium) it also is very hard, but requires the coated pistons, but then you can use the stock ring packages.

honing a aluminum 928/944 block has catostrophic results. however, ive seen one that was "cleaned" up by mistake and it survived, because it was only a light hone, but ask any tech, that engine would have been junk before it went together. he was lucky. you dont hone the 944 or 928 blocks for any reason.

funny, chevy vega started this alusil popularity in blocks!

67King

Wossner sells TONS of 944 pistons with a "credible" coating. Ask Chirs White or Lindsey Racing about them. For that matter, the guy who runs wossneronline is a 944 guy.

jjmohler

I have a '88' engine with some fairly minor scoring on the cylinder walls. At what point do you resleeve? I will be using the original pistons.