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Rebuilding a 928 32V engine, can't identify the pistons!
Hi guys,
I'm trying to re-ring a 5.0 32V engine for a project Euro 1987 928 S4 (engine number M28/44 81F06360), I bought the car with the engine out of the car, it was supposed to be built and let sit in a warehouse since 2001, unfortunately water managed to enter into one cylinder and caused the piston to sieze, I managed to get it out but as dummy as I was that night I broke a small piece and now I have to replace it, please help me to identify it as I googled its part number and found nothing about it! .. the part number is 100188 with number "1" stamped on its surface. I measured it using my micrometer and it was 100mm (mine was in in so I have to convert it to mm, so I'm not %100 sure of accuracy). It looks it has smaller dish area than the pistons I can see in the internet, I'm attaching a photo of it. Please let me know if you have any idea where I can get a replacement one. Thanks!
That motor is from a 1985 automatic, and it's a tolerance group 1 piston. 928 International should have about a million of these available as good used, the part number should be 928 103 065 12.
That motor is from a 1985 automatic, and it's a tolerance group 1 piston. 928 International should have about a million of these available as good used, the part number should be 928 103 065 12.
Thanks mate! .. I have contacted Mark and he right away sent me a quote for 8 very clean pistons, but unfortunately my machine shop gave me the bad news, someone in the past re-sleeved 3 cylinders with normal steel sleeves and that what caused the pistons to seize in the first place! .. now my only option is to re-sleeve all 8 cylinders and search for a normal forged pistons (which I think maybe I can get them custom made) .. Any idea if that practice has been done before? .. I know I'm loosing a great Porsche technology but its my only option, as where I live you just can't find ANY parts for this car.
^^ you can have the actual cylinders cut out and replaced, then rehoned, all with the correct Alusil cylinders. But your shop might not have the ability to do this.
^^ you can have the actual cylinders cut out and replaced, then rehoned, all with the correct Alusil cylinders. But your shop might not have the ability to do this.
Actually they do can do it, but I need to know where I can find the correct aluminum sleeves for it.
There must be someone importing alu-sil liners to the US. I think Mr. Brown is doing it.
However, it is probably cheapest to import on your own, especially now with the exchange rate we have.
If you import something from Germany or another EU country, make sure that the VAT (sales tax) is deducted.
This is how I make my own cylinder liners, here cast iron big bore liners for a Rotax motorcycle engine.
Åke
Whereas I can appreciate reticense to carry out such work in a shop that has not carried out such an operation previously fact is any workshop with such capabiity has to have a first time for anything they do. In this respect you should be able to gather information about how such operations are carried out and armed with the nuances of such discuss with your friendly workshop how they view taking on such a task.When a country builds an international top notch facility for racing [Losail and Moto GP] what tends to happen is that a specialised industry tends to develop around it to provide the necessary services to support motor racing. It happened in Dubai/Abu Dhabi and I dare say such may well happened in Qatar.
I am sure that folks like Ake can also offer you some specific support related to doing such on a 928 if so inclined. Whether or not the engine is worth saving remains to be seen and probably depends on your motivation as well as the cost and logistics involved. The alternative is to contact the likes of Mark with a view to acquiring a replacement short block but even those have invariably covered mileages that suggest a major rebuild would be appropriate.
I might have to go back to the original idea of using iron liners and aluminum pistons, but I thought the aluminum pistons would be lighter than the originals, I'm not sure if at that weight difference the rotating assembly can be balanced correctly, or do you think someone can make them with the same weight as the originals?
08-24-2022, 03:10 PM
Rebuilding a 928 32V engine, can't identify the pistons!
