Preparing/Restoring Alusil bores for Dummies
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Hi All
I have been sure for some time that the process of preparing our blocks for new rings was NOT rocket science or expensive.
The forum entry below is long winded BUT well worth reading and is very detailed. Gets interesting from about page 8 onwards.
http://forums.pelicanparts.com/showt...t=137346&pp=20
The long and the short is that you can easily prepare alusil bores for new rings, so long as they are not mechanically damaged. (Scoured, galled, cracked or pitted)
Conclusion:
Buy some AN30 from Sunnen (50% Silicon powder suspended in oil) this is the product recommended for the final lapping of the alusil bores.
Buy a cheap and cheerful three legged bore honing tool, wrap some rag around its legs, put some AN30 in the bores and polish away!
What this does is to remove some aluminium from the bore to expose some more of the silicon particles for the rings to run on, the 'setback' aliminium provides the space for the oil to go to provide lubrication when the engine is running. (all on microscopic level)
Anyway, check it out.
john
I have been sure for some time that the process of preparing our blocks for new rings was NOT rocket science or expensive.
The forum entry below is long winded BUT well worth reading and is very detailed. Gets interesting from about page 8 onwards.
http://forums.pelicanparts.com/showt...t=137346&pp=20
The long and the short is that you can easily prepare alusil bores for new rings, so long as they are not mechanically damaged. (Scoured, galled, cracked or pitted)
Conclusion:
Buy some AN30 from Sunnen (50% Silicon powder suspended in oil) this is the product recommended for the final lapping of the alusil bores.
Buy a cheap and cheerful three legged bore honing tool, wrap some rag around its legs, put some AN30 in the bores and polish away!
What this does is to remove some aluminium from the bore to expose some more of the silicon particles for the rings to run on, the 'setback' aliminium provides the space for the oil to go to provide lubrication when the engine is running. (all on microscopic level)
Anyway, check it out.
john
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AND.....? Do it yet?
Still wondering about the hone legs (I assume you just cover them stones and all).
What's the chance of metal/stone break-thru -thru the rag- even at low rpm's?
I agree the boring and honing of the 928/944 cylinder blocks could not have been so
futueristic that it wasn't feasable (economic or otherwise) to do by a engine shop.
Anxiously waiting....
What's Mark doing with his engines I wonder... Proprietary?...Jim, what's the skinny ?
Still wondering about the hone legs (I assume you just cover them stones and all).
What's the chance of metal/stone break-thru -thru the rag- even at low rpm's?
I agree the boring and honing of the 928/944 cylinder blocks could not have been so
futueristic that it wasn't feasable (economic or otherwise) to do by a engine shop.
Anxiously waiting....
What's Mark doing with his engines I wonder... Proprietary?...Jim, what's the skinny ?
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The story so far:
Couldn't obtain any of the AN30 so;
After doing a fair bit of research on Alusil (Block material) I decided to gently polish the bores with an aluminium polish to remove a very very small amount of ali and expose some more of the silicon. This is very similar to the final polish the bores get in production, except they used a silicon based abrasive polish (Sunnen AN30). Ali polish is usually ali oxide based.
I wasn't able to buy a three legged hone locally either, so I made do with what I had to hand.
I took a soft cotton rotary mop that just fitted down the bores, coated it with the ali polish and gave each bore a quick couple of up and down whizzes with an electric drill. Made quite a difference, and I made bl**dy sure I removed all traces of the polish! The mop turned black as the polish removed some of the ali (microscopic level here)
Looking at the sort of surface finishes shown in pictures of 'sunnened' blocks I managed to obtain the same sort of visual apperence. The bores felt very smooth, and when coated with engine oil they seemed to almost 'suck it up' some how.
The engine turned over easily by hand with the plugs out, but fantastic compression with the plugs in.
The engine is now back in my car and running beautifully, seems more responsive, and oil pressure is up on hot idle (3.5Bar). Early days but I am trying to put miles on as quickly as I can.
Oil is still clean, although I have been advised that the new rings can throw quite a bit of rubbish into the oil. Running on 15w-40 semi synthetic, been advised to change to a 20w-50 as this can help with better bearing protection?
I will keep posting as my engine either:
1. Settles down for he long haul.
or
2. Destroys itself due to my unauthordox preperation!
John
Couldn't obtain any of the AN30 so;
After doing a fair bit of research on Alusil (Block material) I decided to gently polish the bores with an aluminium polish to remove a very very small amount of ali and expose some more of the silicon. This is very similar to the final polish the bores get in production, except they used a silicon based abrasive polish (Sunnen AN30). Ali polish is usually ali oxide based.
I wasn't able to buy a three legged hone locally either, so I made do with what I had to hand.
I took a soft cotton rotary mop that just fitted down the bores, coated it with the ali polish and gave each bore a quick couple of up and down whizzes with an electric drill. Made quite a difference, and I made bl**dy sure I removed all traces of the polish! The mop turned black as the polish removed some of the ali (microscopic level here)
Looking at the sort of surface finishes shown in pictures of 'sunnened' blocks I managed to obtain the same sort of visual apperence. The bores felt very smooth, and when coated with engine oil they seemed to almost 'suck it up' some how.
The engine turned over easily by hand with the plugs out, but fantastic compression with the plugs in.
The engine is now back in my car and running beautifully, seems more responsive, and oil pressure is up on hot idle (3.5Bar). Early days but I am trying to put miles on as quickly as I can.
Oil is still clean, although I have been advised that the new rings can throw quite a bit of rubbish into the oil. Running on 15w-40 semi synthetic, been advised to change to a 20w-50 as this can help with better bearing protection?
I will keep posting as my engine either:
1. Settles down for he long haul.
or
2. Destroys itself due to my unauthordox preperation!
John
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John,
That is good news, I haven't heard of anyone like a do-it-yourselfer taking on this challenge. I hope it works out great for you. The fact that its doing good right now for the first days is encouraging news too.
I have some aluminum polish here made in Germany, comes in a 1 quart can. I think its called Tec, or some other 3 letter name. I will have to go look for it.
So for instance, a person needs to bore his motor .030" over, could he feasably take it to a shop, do that and then use this honing process? Or would it be bore, hone and then polish? Maybe its too early to know.
But one of our 928 experts might know how it works...
That is good news, I haven't heard of anyone like a do-it-yourselfer taking on this challenge. I hope it works out great for you. The fact that its doing good right now for the first days is encouraging news too.
I have some aluminum polish here made in Germany, comes in a 1 quart can. I think its called Tec, or some other 3 letter name. I will have to go look for it.
So for instance, a person needs to bore his motor .030" over, could he feasably take it to a shop, do that and then use this honing process? Or would it be bore, hone and then polish? Maybe its too early to know.
But one of our 928 experts might know how it works...
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#8
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Originally Posted by johnb
The engine is now back in my car and running beautifully, seems more responsive, and oil pressure is up on hot idle (3.5Bar). Early days but I am trying to put miles on as quickly as I can.
John
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Rick
I have completely rebuilt my engine, new bearing shells alround, less space for oil leakage; therefore slightly higher oil pressure at idle.
john
I have completely rebuilt my engine, new bearing shells alround, less space for oil leakage; therefore slightly higher oil pressure at idle.
john
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Originally Posted by johnb
Oil is still clean, although I have been advised that the new rings can throw quite a bit of rubbish into the oil. Running on 15w-40 semi synthetic, been advised to change to a 20w-50 as this can help with better bearing protection?
John
John
This is very critical in aircraft(chrome rings on steel, air cooled) but the theory is the same for Iron on Al bores. I thought the 928 had Nikasil coated bores? I must be confusing it with the Mondial, hmmmmm.
#11
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Originally Posted by johnb
The engine is now back in my car and running beautifully, seems more responsive, and oil pressure is up on hot idle (3.5Bar). Early days but I am trying to put miles on as quickly as I can.
Oil is still clean, although I have been advised that the new rings can throw quite a bit of rubbish into the oil.
Oil is still clean, although I have been advised that the new rings can throw quite a bit of rubbish into the oil.
Running on 15w-40 semi synthetic
Man, great job getting this done so quickly!
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And here's to a perfectly running engine:
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#12
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john, like everyone else im keen to see how the engine goes with the alluminium polish you used! i also wonder if its not best to use regular dyno oil during break in. how are you breaking in the engine by the way? i opted to basicaly cain mine after warming it up
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#13
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I have read that Corvettes and Camaros are factory filled with synthetic oil. Not aluminum bores I agree but still trying to seat iron rings. Must be a reason for the added expense.
Brian.
Brian.
#14
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Originally Posted by bkingdon
I have read that Corvettes and Camaros are factory filled with synthetic oil. Not aluminum bores I agree but still trying to seat iron rings. Must be a reason for the added expense.
#15
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I had my 5.0l hybrid bores 'freshened' by a local machine shop. They did some research with Sunnen and determined that it was the same product and process as used for the chebie vega blocks. They had everything - I think I paid less than $200...