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Piston Difference

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Old Aug 9, 2011 | 06:52 PM
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Default Piston Difference
What, if any, is the use of the holes on each side of the wrist pin on my factory piston? The replacement piston I got doesn't have them. They are both the same tolerance group.

Do I need to get a piston with these holes or just make sure they weigh the same?

piston2.jpg
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Old Aug 9, 2011 | 08:44 PM
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Porsche found that oil was getting trapped in the pin area and having a tough time returning, past the "full lower skirt".

There was a technical bulletin about drilling the holes. #8806. Book "E". page 39.
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Old Aug 9, 2011 | 09:15 PM
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Default holes
So I'll take the new piston to the shop that did my heads and tell them to drill it out and make it look like my old one and call it good?
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Old Aug 9, 2011 | 09:20 PM
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weigh the piston before you drill as well as after so you can compare the weights so it will match your old one
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Old Aug 9, 2011 | 10:16 PM
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The new (used) replacement piston is 4 grams heavier than the old piston. I bet the difference is in the holes.
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Old Aug 9, 2011 | 11:28 PM
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Originally Posted by jeff spahn
So I'll take the new piston to the shop that did my heads and tell them to drill it out and make it look like my old one and call it good?
There are detailed instruction in the technical bulletin...but your way should work fine.
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Old Aug 9, 2011 | 11:30 PM
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Originally Posted by jeff spahn
The new (used) replacement piston is 4 grams heavier than the old piston. I bet the difference is in the holes.
Four grams is a bunch. After they machine the holes, ask them to match the new piston to the old piston.
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Old Aug 9, 2011 | 11:36 PM
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at least you can remove it! the holes will probably do it.
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Old Aug 10, 2011 | 08:40 AM
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My TSB's start at "F" as in "FVCK, why don't I have E!" Calling out to Rob Edwards, or anyone for a scan of the TSB #8806 Book E that they could email to me at jspahn@mac.com
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