jensend3

So I'm doing a rebuild and I'm thinking of honing the cylinders myself. I know what your thinking; don't do it! However I go to an aeronautical university and my friend who attended their aircraft mechanic training has access to all of their machining equipment. Supposedly aircraft use special cylinder processes just like our 944's. Probably hypereutectic aluminum and maybe even the same Alusil patent. He couldn't tell me the specific names off hand, but he did say the reason behind it is incase of an engine failure, the less friction the more freely the engine and prop can turn.

Anyways I know sunnen makes the stuff I would need, and according to their site the honing itself is pretty standard and the chemical treatment sounds pretty straight forward. After the honing I believe you use an elastic, or cushioned stone to apply the treatment for 1.5 minutes then use a Profilometer to ensure that the walls have a specific roughness.

You may already know, but basically our blocks are something like 30% silicon, 70% aluminum. The paste eats away the aluminum and then leaves a porous coating of hard silicon that is like riding on oil saturated porous glass.

Does anyone know where to find the paste, or the name or brand of it, that is required for the treatment. I'm certain the aircraft maintenance facilities have the proper equipment on hand. It's just a matter of know which equipment to use.

Mike C.

I do know the 944 shop manual does detail the steps for doing this. IIRC, they call it silicium paste. I assume this paste has an acidic content that etches the aluminum matrix so it is recessed from the silicon. Let us know how it goes.

jensend3

I'm glad you brought that up, because I was just wondering whether or not the factory manual details that process. So far clarks_garage and the haynes manual have been good enough, but what is the best route to get access to the factory information. I've seen some computer based manuals selling on ebay for $20. The claim to have all of the information. Does anyone know if thats true.

jensend3

by the way. this is the ad on ebay im talking about. http://cgi.ebay.com/ebaymotors/1983-...ht_4771wt_1167

944Ross

Here are some free manuals, scans of the FSM

http://www.eucc.dk/

jensend3

Oh man, thanks for the manuals. I really appreciate that.

kev951

i believe its sunnen an 15 or 20 paste , something like that

John_AZ

HondaDustR detailed a complete engine rebuild. His information on honing is included and tools used.
Very thorough.

http://forums.pelicanparts.com/porsc...placement.html

GL
John

Smoker324

I can second John's reference to HondaDustr's thread. Last time I spoke to him he had more than 10K on the rebuild -- with reseated rings and no appreciable oil consumption.

FRporscheman

I'm blown away, I had no idea this was something I could do myself. How much would honing cost at a shop?

Mike C.

Many years ago it cost me $100 per hole.

944CS

You'll need a torque plate - add a few hundred

AScholtes

no need for a torque plate to hone a cylinder... for boring a cylinder yes, but not for honing. Honing is just creating a finish on the cylinder wall.

Dare

In case you haven't seen these, the following links contain some interesting reading on the subject:
The last one seems to be an earlier revision of the first, however it contains some 944 specific information that was omitted in the latter document.

Also, the original link for the last document appears to be dead, but google cache still retains a copy (as do I).

John_AZ

Great links! ^^
Thanks
John