OMG! DIY Cylinder Honing
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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.
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.
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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.
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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.
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by the way. this is the ad on ebay im talking about. http://cgi.ebay.com/ebaymotors/1983-...ht_4771wt_1167
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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
Very thorough.
http://forums.pelicanparts.com/porsc...placement.html
GL
John
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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.
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In case you haven't seen these, the following links contain some interesting reading on the subject:
Also, the original link for the last document appears to be dead, but google cache still retains a copy (as do I).
Reconditioning of Aluminium Engine Blocks
New Honing Options for Hypereutectic Aluminum Cylinder Bores
Reconditioning of Aluminium Engines
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.New Honing Options for Hypereutectic Aluminum Cylinder Bores
Reconditioning of Aluminium Engines
Also, the original link for the last document appears to be dead, but google cache still retains a copy (as do I).