Drilling GTS pistons?
02-09-2009, 10:34 AM
#46
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This is how it goes when dealing with a German....who will never admit that they did anything wrong.
They will insist that the real problem is that the oil control rings are in the wrong place in relationship to the other rings due to some harmonic or frequency that they have found, previously unknown to all others. They will redesign the piston, moving the rings, a bit. The oil drain back holes will magically appear in the redesign, but will not be talked about. All parties will know what the problem was and what the solution was, but they will never talk about it. It's the German way.
They will insist that the real problem is that the oil control rings are in the wrong place in relationship to the other rings due to some harmonic or frequency that they have found, previously unknown to all others. They will redesign the piston, moving the rings, a bit. The oil drain back holes will magically appear in the redesign, but will not be talked about. All parties will know what the problem was and what the solution was, but they will never talk about it. It's the German way.
They are still trying to find a quiet way to move the engine to a proper location.
02-09-2009, 12:49 PM
#47
This is how it goes when dealing with a German....who will never admit that they did anything wrong.
They will insist that the real problem is that the oil control rings are in the wrong place in relationship to the other rings due to some harmonic or frequency that they have found, previously unknown to all others. They will redesign the piston, moving the rings, a bit. The oil drain back holes will magically appear in the redesign, but will not be talked about. All parties will know what the problem was and what the solution was, but they will never talk about it. It's the German way.
They will insist that the real problem is that the oil control rings are in the wrong place in relationship to the other rings due to some harmonic or frequency that they have found, previously unknown to all others. They will redesign the piston, moving the rings, a bit. The oil drain back holes will magically appear in the redesign, but will not be talked about. All parties will know what the problem was and what the solution was, but they will never talk about it. It's the German way.
02-09-2009, 03:40 PM
#48
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If this is a common problem to all these engines can someone please explain to me why my late model 93 doesn't ping or burn oil. I know the heads or engine have never been removed on my car. I reviewed and discussed this with a well known 928 Porsche trained mechanic and he agrees. Although I had an occasional sticky lifter that is no longer an issue I have none of the normal issues associated with a 93 MY engine. It sounds like this should not be the case for any 93 or any GTS for that fact.
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greg brown
714 879 9072
GregBBRD@aol.com
Semi-retired, as of Feb 1, 2023.
The days of free technical advice are over.
Free consultations will no longer be available.
Will still be in the shop, isolated and exclusively working on project cars, developmental work and products, engines and transmissions.
Have fun with your 928's people!
02-09-2009, 03:55 PM
#49
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Someone I used to work with had German ancestry - he had a poster on his wall poking fun at himself...
It said - "You can allways tell a German.... but you can't tell him much "
Seems very applicable...
Very good data gentlemen - thanks esp. Greg for the confirmation of plan if I ever need to rebuild mine.
Alan
It said - "You can allways tell a German.... but you can't tell him much "
Seems very applicable...
Very good data gentlemen - thanks esp. Greg for the confirmation of plan if I ever need to rebuild mine.
Alan
02-09-2009, 04:44 PM
#50
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Yes matching numbers. Also all hose clamps and fittings are turned around without any glitches or scratches as though they were installed that way from the factory. When I changed my hoses when I first got the car I had to cut them out because there was no way to access any of the clamps. I had a local 928 specialist look at it and his opinion was that the car was not altered from original. I also spoke to both previous owners and other than the sticking lifter and battery drain issues early on they said the car ran perfectly without oil consumption. Neither had any knowledge of the engine being worked on.
11-08-2010, 01:05 PM
#51
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Was straightening up in the garage yesterday and recalled no one had posted a pic of the UNdrilled GTS oil ring holes. Try to ignore the scoring, skirt chunks, and bent rod....
11-08-2010, 03:40 PM
#53
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I have the later style pistons - BUT:
- they have cut-outs for 39mm intake valves
- they are made by Kolbenschmidt, usually its Mahle
- they have 4 blind holes (the ones closest to the pin) and 4 holes drilled through
- the engine has been sleeved by Porsche with some material, which is not alusil - remarkably different from the block material. Seems more like steel
- Material code does not match what Porsche has in the literature
What have I got - experiMental engine?
- they have cut-outs for 39mm intake valves
- they are made by Kolbenschmidt, usually its Mahle
- they have 4 blind holes (the ones closest to the pin) and 4 holes drilled through
- the engine has been sleeved by Porsche with some material, which is not alusil - remarkably different from the block material. Seems more like steel
- Material code does not match what Porsche has in the literature
What have I got - experiMental engine?
This is a process which I'm likely to be embarking on shortly as mine's an early 93 GTS ROW car and whilst the oil consumption is accoridng to Porsche "wthin tolerance" I still consider it excessive.
11-09-2010, 04:36 AM
#54
I have the later style pistons - BUT:
- they have cut-outs for 39mm intake valves
- they are made by Kolbenschmidt, usually its Mahle
- they have 4 blind holes (the ones closest to the pin) and 4 holes drilled through
- the engine has been sleeved by Porsche with some material, which is not alusil - remarkably different from the block material. Seems more like steel
- Material code does not match what Porsche has in the literature
What have I got - experiMental engine?
- they have cut-outs for 39mm intake valves
- they are made by Kolbenschmidt, usually its Mahle
- they have 4 blind holes (the ones closest to the pin) and 4 holes drilled through
- the engine has been sleeved by Porsche with some material, which is not alusil - remarkably different from the block material. Seems more like steel
- Material code does not match what Porsche has in the literature
What have I got - experiMental engine?
I think the liners are a variation of alusil with different proportions of al and sil. The reasons I don't think they are steel are: They are very thin and if they were steel the different rates of expansion could cause issues. I saw pictures of the sleeved block, there were water marks on the top of the block including on the sleeves, but no rust colouration.
11-09-2010, 12:32 PM
#55
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I have a friend that HAD a GTS and converted it to a stroker. its an Alusil stroker,with coated pistons and was rumored to be so tight, that the pistons had to be frozen to get them in the blocks. Yet, it burns almost 1 quart every 150 miles . how in the heck is this possible, and what could cause it. oil rings not seating ? (doesnt seem likely). broken ring from the start? (doesnt seem likely), and it doesnt smoke, only on WOT operation a little, but it could be rich too, but the smoke certainly has a blue hue to it.
11-09-2010, 01:50 PM
#56
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Is that the ex CB engine? Did the replacement engine come before the rebuild with replacement block or the other way around?
I think the liners are a variation of alusil with different proportions of al and sil. The reasons I don't think they are steel are: They are very thin and if they were steel the different rates of expansion could cause issues. I saw pictures of the sleeved block, there were water marks on the top of the block including on the sleeves, but no rust colouration.
I think the liners are a variation of alusil with different proportions of al and sil. The reasons I don't think they are steel are: They are very thin and if they were steel the different rates of expansion could cause issues. I saw pictures of the sleeved block, there were water marks on the top of the block including on the sleeves, but no rust colouration.
Yes, it is the ex CB engine. The replacement engine came as a crate engine - everything ready to go from the factory on a pallet, minus the anxilaries... You might be onto something with the liners - I have always thought that steel was unlikely candidate for the liners, given that they are pressed in and are very thin. Btw, 2500 race miles cleaned them up beautifully...
Mark K,
Your friend is not using Amsoil, that's all
