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Old 04-17-2009, 07:39 PM   #1
04psmgt35sti
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Default .020 over on an sti anyone?

Just thinkin about goin .020 over when i get the block to the machine shop? Anyone have any problems cracking cylinder walls at .020?
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Old 04-17-2009, 08:25 PM   #2
reddevil
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That what you SHOULD do with new pistons to ensure an accurate fit, just not everybody does as its "usually" not needed. People split cylinder walls at stock levels anyway....
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Old 04-19-2009, 11:45 PM   #3
04psmgt35sti
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bump, i need to find out if want to go .020 over this by tuesday!
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Old 04-20-2009, 12:05 AM   #4
cribbie
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If your cylinder run out is within specs then leave them alone. .020 is just a clean up job you wont get anything out of it.
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Old 04-20-2009, 12:31 AM   #5
alcoolaid
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Measure the bores first then decide. You might be able to get away with 99.5mm or 99.75mm pistons.
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Old 04-20-2009, 01:11 AM   #6
AWDWRXLOVER
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100 mils are fine but if i could do it again i would have done 99.75 so i would have room for a future rebuild.
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Old 04-20-2009, 01:27 AM   #7
Team Scream
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I am sitting here with a set of case halves from an 05 STi engine tear down i just did.
I am thinking I will probably go with the 99.75 if I have to do anything at all.
The engine only had 17K on it when the guy that owned it crashed it.....(I bought the whole car for parts).
As you can imagine everything looked near new when I disassembled the engine, and I would like to leave room for a future clean up as well.
99.75 will ensure that you get the piston to wall clearance you want/need and is more of an aggressive hone than a bore job so it may even cost you less. ?

If you do not already have pistons, you have no reason to be dropping that block off at the machine shop for any bore work my friend.
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Old 04-20-2009, 07:05 AM   #8
cribbie
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By the sounds of it some people like to throw away there money for no reason...have your block measured out if isn't within spec then go .020 over and if it is within spec then move on to the next question...
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Old 04-20-2009, 01:37 PM   #9
Fongers
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100mm should be fine and its just extra insurance to give you more some for the bore and piston match.
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Old 04-20-2009, 09:06 PM   #10
04psmgt35sti
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I dropped the two casings off today and had him measure the walls. As expected number 4 was slightly out at the top so he honed it to see how far off we were. He said he honed it to .009 and it tested perfect so i just ordered my pistons through wiseco (apparentley you have to order 99.75's custom because they don't offer it). 4 weeks and i'll recieve the new pistons for the shop to hone out to spec
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Old 04-21-2009, 03:34 AM   #11
alcoolaid
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CP makes a 99.75mm. I got them in 3 days with a crown and skirt coating.
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