joes

A friend of mine broke a ring and scratched a cylinder wall. The porsche manual calls for a process of boring and honing with special tool (felt pads) and some "Sunnen ck- 10/cv=616 to bring out the silicium particles'

Other people that I have talked to say that they have to be re-coated with alumasil or nikasil. Can someone elaborate on these processes or and suggest the most common way to repair this problem?

Dave951M

It might be cheaper to get another block than to bore and hone it.

Dave

Alusil is not a coating, it's the material the block is made out of. I would assume the manual is correct but I haven't read it. As I understand it the block is first bored as a "normal" block would be bored, it then needs to be etched to remove a little aluminum from between the silicon crystals, finally the silicon is honed/buffed/worked until it is smooth, creating a cylinder wall made of silicon. Before you even think of having this done, oversize pistons are expensive and hard to find. A good used block might be a better alternative.

joes

Has anyone went through this process?

Larry Parker

I had mine done in michigan for 150.00.......

joes

Larry, did they do all four and how did it hold up?

adrial

If the scratches aren't too deep, then the cleanup process with the felt pads and special paste is fine and very economical ($200ish). If the scratches are deep, then you need first oversized pistons ($$$) and to actually machine the block.

Larry Parker

They worked fantastic.... And I had to get 104.5mm pistons first (not an easy task)........

Many people that are fimiliar with the OLD GM costhworth vega motor will know this process....First they boar and then they lap......

Not a big deal.... just like doing a steel block with an extra step.......

All those damn 944 shop Hose the **** out of people to do this job! If any one can bore a motor its here in DETROIT!!

Cheers

HY M8NC

Probably the cheapest way to bore the motor is to let it talk to my sister-always bores the hell out of me.

I agree with having a competent machine shop look at it. There are a lot of specialized motors around these days, so any shop that is worth your time (and $$) should have a good understanding of the requirements the 944 block has.