can a damaged block be repaired?
02-23-2017, 06:47 PM
#47
Nordschleife Master
I've never claimed that I understand fashion. I can to some extent predict it, though.
Take the case of modern Porsches, for example. I find the marketing all sizzle and no steak. At least AMG hasn't forgotten to put some actual car into the marketing mix, instead of Porsche's just image, image, image.
The same way, the 928 market pays a premium for the GTS. It's objectively a lot worse car than S4/GT, and a lot more expensive to maintain. Yet, GTS is very much in fashion in the 928 market.
In the 928 aftermarket, fashions seem to come and go. Dry sleeving with iron or steel sleeves used to be a faux pas. Now it's the RL best practice and has received the coveted good housekeeping seal of approval! This leaves me longing for the old days, when Alusil cylinders were repaired with Alusil sleeves and the best practice was to repair only the damaged cylinder.
In terms of technical content, I think that there are a large number of four cylinder Porsches that survive well with wet sleeves and a smaller but non-zero number of 928's that also survive well with wet sleeves. Mike Simard's 7.0L V8 comes to mind. This leads me to conclude is that it's not wet sleeves per se that are ill advised, it's implementing wet sleeves without sufficient engineering expertise that is ill advised. I predict that this opinion will not be fashionable here...
The size of the silicon crystals in Alusil depend critically on the rate at which that part of the casting cools. From the source that Ake shared:
So the silicon crystals are larger at the bottom of the towers. They are also larger if the cylinder is overbored. Not that there's anything wrong with it, my logic says that this may in fact be advantageous considering it's going to be sliding surface. The above quote may also shed some light to the earlier debate about whether Alusil is an alloy or not.
The blower-BBC conversion in that old photo would possibly be even louder than my turbo 928 with the silent night exhaust.
World doesn't make sense to me, but I'm not going to fight it. I just worked out in Prada sneakers, so I'm hating the game and not the player.
Take the case of modern Porsches, for example. I find the marketing all sizzle and no steak. At least AMG hasn't forgotten to put some actual car into the marketing mix, instead of Porsche's just image, image, image.
The same way, the 928 market pays a premium for the GTS. It's objectively a lot worse car than S4/GT, and a lot more expensive to maintain. Yet, GTS is very much in fashion in the 928 market.
In the 928 aftermarket, fashions seem to come and go. Dry sleeving with iron or steel sleeves used to be a faux pas. Now it's the RL best practice and has received the coveted good housekeeping seal of approval! This leaves me longing for the old days, when Alusil cylinders were repaired with Alusil sleeves and the best practice was to repair only the damaged cylinder.
In terms of technical content, I think that there are a large number of four cylinder Porsches that survive well with wet sleeves and a smaller but non-zero number of 928's that also survive well with wet sleeves. Mike Simard's 7.0L V8 comes to mind. This leads me to conclude is that it's not wet sleeves per se that are ill advised, it's implementing wet sleeves without sufficient engineering expertise that is ill advised. I predict that this opinion will not be fashionable here...
The size of the silicon crystals in Alusil depend critically on the rate at which that part of the casting cools. From the source that Ake shared:
In contrast to the hypereutectic alloy, [an] eutectic aluminium silicon alloy contains only 12-13% silicon. with this silicon content the saturation degree is reached. A greater silicon content will cause primary silicon crystals to form when the molten metal coagulates. This means that the silicon content that cannot be alloyed to the aluminum due to the saturation of the aluminum crystallises will be deposited in the (saturated) aluminium silicon alloy (eutetic). A small amount of phosphorous is added to the molten metal to help the silicon crystallization process. The silicon crystals grow around a heterogenous aluminum phosphide nucleus. The size of the silicon crystals ranges from 20 to 70 micrometers. After appropriate processing and exposing of these primary silicon crystals, they form the hard, wear-resistant cylinder sliding surface without additional reinforcement. ...The longer the coagulation process, the larger the silicon crystals become. The different cooling rates within the engine block cause silicon crystals to form in the lower cylinder area somewhat larger than in the upper cylinder area which cools off faster because of its design.
The blower-BBC conversion in that old photo would possibly be even louder than my turbo 928 with the silent night exhaust.
World doesn't make sense to me, but I'm not going to fight it. I just worked out in Prada sneakers, so I'm hating the game and not the player.
Last edited by ptuomov; 02-23-2017 at 07:07 PM.
02-26-2017, 05:40 AM
#48
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Join Date: Feb 2009
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ok,
Some update- I will read all the replay later.. been busy with other things these days.
I went there yesterday & The mechanic that took out the engine didn't felt confident at all for a repair block.
He said to me there is a possibility that he may find a jammed GTS engine for sale around here. He said the block might be still ok. He will let me know.
Some update- I will read all the replay later.. been busy with other things these days.
I went there yesterday & The mechanic that took out the engine didn't felt confident at all for a repair block.
He said to me there is a possibility that he may find a jammed GTS engine for sale around here. He said the block might be still ok. He will let me know.