.020 over on an sti anyone?

04psmgt35sti · 04-17-2009, 07:39 PM

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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reddevil · 04-17-2009, 08:25 PM

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....

04psmgt35sti · 04-19-2009, 11:45 PM

bump, i need to find out if want to go .020 over this by tuesday!

cribbie · 04-20-2009, 12:05 AM

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.

alcoolaid · 04-20-2009, 12:31 AM

Measure the bores first then decide. You might be able to get away with 99.5mm or 99.75mm pistons.

AWDWRXLOVER · 04-20-2009, 01:11 AM

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.

Team Scream · 04-20-2009, 01:27 AM

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.

cribbie · 04-20-2009, 07:05 AM

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...

Fongers · 04-20-2009, 01:37 PM

100mm should be fine and its just extra insurance to give you more some for the bore and piston match.

04psmgt35sti · 04-20-2009, 09:06 PM

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

alcoolaid · 04-21-2009, 03:34 AM

CP makes a 99.75mm. I got them in 3 days with a crown and skirt coating.

04-17-2009, 07:39 PM	#1
04psmgt35sti Scooby Newbie Member#: 203623 Join Date: Feb 2009 Location: Sandy, Utah Vehicle: 2004 STI 464whp	.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? * Registered users of the site do not see these ads.

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04-17-2009, 08:25 PM	#2
reddevil Scooby Guru Member#: 64673 Join Date: Jun 2004 Chapter/Region: NWIC Location: portland Vehicle: 1990 Legacy wagon goes 12.387 @ 116.5	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....

04-19-2009, 11:45 PM	#3
04psmgt35sti Scooby Newbie Member#: 203623 Join Date: Feb 2009 Location: Sandy, Utah Vehicle: 2004 STI 464whp	bump, i need to find out if want to go .020 over this by tuesday!

04-20-2009, 12:05 AM	#4
cribbie Scooby Specialist Member#: 184505 Join Date: Jul 2008 Chapter/Region: E. Canada Location: Ontario Vehicle: 2003 WRX Sonic yellow	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.

04-20-2009, 12:31 AM	#5
alcoolaid Scooby Guru Member#: 134949 Join Date: Dec 2006 Chapter/Region: VIC Location: Vancouver, BC Vehicle: '07 SWP STi Twinscroll ViPec Anti-lag	Measure the bores first then decide. You might be able to get away with 99.5mm or 99.75mm pistons.

04-20-2009, 01:11 AM	#6
AWDWRXLOVER Scooby Specialist Member#: 50267 Join Date: Dec 2003 Chapter/Region: SWIC Vehicle: 02 built hybrid sr55/meth/sick speed	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.

04-20-2009, 01:27 AM	#7
Team Scream Scooby Specialist Member#: 121532 Join Date: Jul 2006 Chapter/Region: SCIC Vehicle: 2006 FXT/STi 6MT 01 Aerosim GC8 Coupe	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.

04-20-2009, 07:05 AM	#8
cribbie Scooby Specialist Member#: 184505 Join Date: Jul 2008 Chapter/Region: E. Canada Location: Ontario Vehicle: 2003 WRX Sonic yellow	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...

04-20-2009, 01:37 PM	#9
Fongers Scooby Specialist Member#: 118239 Join Date: Jun 2006 Chapter/Region: SCIC Location: Beijing and Venice Beach Vehicle: 2002 Built Wagon Wife- 2004 Outback SE	100mm should be fine and its just extra insurance to give you more some for the bore and piston match.

04-20-2009, 09:06 PM	#10
04psmgt35sti Scooby Newbie Member#: 203623 Join Date: Feb 2009 Location: Sandy, Utah Vehicle: 2004 STI 464whp	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

04-21-2009, 03:34 AM	#11
alcoolaid Scooby Guru Member#: 134949 Join Date: Dec 2006 Chapter/Region: VIC Location: Vancouver, BC Vehicle: '07 SWP STi Twinscroll ViPec Anti-lag	CP makes a 99.75mm. I got them in 3 days with a crown and skirt coating.