Welcome to the North American Subaru Impreza Owners Club Friday March 29, 2024
Home Forums Images WikiNASIOC Products Store Modifications Upgrade Garage
NASIOC
Go Back   NASIOC > NASIOC Technical > Built Motor Discussion

Welcome to NASIOC - The world's largest online community for Subaru enthusiasts!
Welcome to the NASIOC.com Subaru forum.

You are currently viewing our forum as a guest, which gives you limited access to view most discussions and access our other features. By joining our community, free of charge, you will have access to post topics, communicate privately with other members (PM), respond to polls, upload content and access many other special features. Registration is free, fast and simple, so please join our community today!

If you have any problems with the registration process or your account login, please contact us.







* As an Amazon Associate I earn from qualifying purchases. 
* Registered users of the site do not see these ads. 
Reply
 
Thread Tools Display Modes
Old 01-14-2014, 10:34 PM   #1
BeastianSTI
Scooby Specialist
 
Member#: 310506
Join Date: Feb 2012
Chapter/Region: South East
Location: Florida
Vehicle:
2005 WRX STi
CGM

Default Rebuilding 05 STi

Hey guys,

So my 2005 STi block blew a ringland @ 145,000 miles. Instead of trading the car off, I want to build it with forged internals. I've pulled WRX engines a couple of times, so I don't think this will be any different. Also stripped it down to the shortblock, but didn't do any part installation after that, aside from torqueing heads to block.

I'm kind of mapping and planning it all out, but will need some help here and there from you guys haha. I have been very interested in doing this myself for a while now, so this is finally my chance.

I'd like to have this guide for semi-technical people that need to rebuild they own block. Nothing too crazy.

What i'm thinking the order of things will be:

1. Remove engine and strip apart everything; labeling all bolts using cardboard / perm. marker. Painters tape for hoses / wires just in case.

2. Send to machine shop to determine what size i'll need to bore to since the cylinder wall may be scored. Shop will be using ej257 torque plate. Having the machine shop deck short block and heads, bore to 99.75mm ( 20 over ), redo valve stem seals and pressure test heads to make sure its all good.

3. Have heads and block hot tanked.

4. Order full gasket set. Will need 99.75mm head gasket or 100mm depending. I'm not sure how thick the gasket needs to be though, to maintain compression. Kind of confused about that.

5. Order ACL race rod / main bearings based on what I find on the block and after inspection of crank surface that mates with the rod bearings.

6. Order CP Pistons for matching 99.75mm pistons or whichever bore.

7. Spray block down with brake parts cleaner, especially in oil galleys for any excess metal from machining.

8. - TBC ... let me get this far.






Is my EJ257 #3 or #5 thrust for mainbearings ? Whats the easiest way to tell?



How will I know what thickness of headgasket to get to maintain safe compression?



When pistons say they're 99.75 bore, does that mean that they fit perfectly for a 99.75 block bore? How do you know what size to bore the block to?



Some people say not to use plasti-gauge in the measurement process whatsoever, which I completely understand and agree that it could be better. I think for the rods you measure the internal diameter of the rod, and then use a micrometer to measure the crank. Do you just subtract those two numbers to determine what size bearing you need, less some clearance constant? How would you measure the diameter of the main bearing areas ( not the bearings )?

Thanks guys!
* Registered users of the site do not see these ads.
BeastianSTI is offline   Reply With Quote
Sponsored Links
* Registered users of the site do not see these ads.
Old 01-15-2014, 11:01 AM   #2
BeastianSTI
Scooby Specialist
 
Member#: 310506
Join Date: Feb 2012
Chapter/Region: South East
Location: Florida
Vehicle:
2005 WRX STi
CGM

Default

Bump - too many questions?
BeastianSTI is offline   Reply With Quote
Old 01-15-2014, 12:10 PM   #3
veritasaequitas
*** Banned ***
 
Member#: 333964
Join Date: Oct 2012
Chapter/Region: MWSOC
Location: https://t.me/pump_upp
Vehicle:
Juli sti
JuliusVetJD

Default

The thickness of the head gasket will depend on how much needs to be taken off. The machinist should be capable of telling you what size you need when he is done. Many people don't suggest boring out our engines depending on the power level they run. If you plan on doing any internal work now wouldbe the time to do it. If youdo decide to bore out 25 over I have a brand new set of cp pistons for sale. I decided to go the route of buying a block assembled from element tuning so I won't need them m
veritasaequitas is offline   Reply With Quote
Old 01-15-2014, 12:23 PM   #4
o4wrxwagon
Scooby Newbie
 
Member#: 213945
Join Date: Jun 2009
Location: Rochester NY
Vehicle:
04 wrx wagon
PSM

Default

Your car is most likely a #5 thrust bearing. Number 3 bearings are located pretty much in the middle of the crank. The number 5's will be where the fly wheel attaches to. if i'm right, mostly all ej25 motors after 01? were number 5.
o4wrxwagon is offline   Reply With Quote
Old 01-15-2014, 12:43 PM   #5
BeastianSTI
Scooby Specialist
 
Member#: 310506
Join Date: Feb 2012
Chapter/Region: South East
Location: Florida
Vehicle:
2005 WRX STi
CGM

Default

Thanks for the response guys--

I'm shooting for 1.5 DOM level power. Nothing too far over 430WHP. I'm planning on keeping the STI rods, since they should hold fine for this application. So do most people rely on the machine shop to tell them what size piston / rings / head gasket?

What is a safe compression ratio to go with, with pump gas?
BeastianSTI is offline   Reply With Quote
Old 01-15-2014, 01:54 PM   #6
BeastianSTI
Scooby Specialist
 
Member#: 310506
Join Date: Feb 2012
Chapter/Region: South East
Location: Florida
Vehicle:
2005 WRX STi
CGM

Default

Also, do I need to have the crank / mains remeasured, even if there wasn't any crank related issues?
BeastianSTI is offline   Reply With Quote
Old 01-15-2014, 02:03 PM   #7
2Fast4U1DAY
Scooby Specialist
 
Member#: 250152
Join Date: Jun 2010
Chapter/Region: MAIC
Location: Pennsylvania
Vehicle:
2006 WRX Limited
OBP

Default

Quote:
Originally Posted by BeastianSTI View Post
Also, do I need to have the crank / mains remeasured, even if there wasn't any crank related issues?
Always. Ive torn apart several blocks that have been OOR (out of round) pretty bad and some even had completely misaligned bores. Heck ive pulled a few "newer" (less than 20k miles) cases that were off by as much as .004

Having an improperly shaped or sized journal or bore can cause oiling issues and spun bearings. I have seen misaligned crank bores even snap a crank.

As for relying on the machine shop to tell you what size pistons pistons you need, I would definitely follow their advice. You have no idea if the block is scored or how much wear has actually taken place unless you measure for yourself with a Dial bore gauge (not a cheapo one either). Judging by your questions im assuming you dont have mics or bore gauges so yes I would not divert from what you builder says. However, Rings should come with the piston set, and unless you are going over a 100 mm bore stock gasket will do unless you need a specific thickness due to machining the deck of the block or heads or both

As for CR I would stay 8.2 for safety. At 8.9 you raise the risk of knock on pump due to more heat generated from compression, and pump fuels inconsistencies. If you were running E or meth or Racegas then you can get away with the higher compression as the higher octane will help combat knock, due to their higher resistance to detonation

Last edited by 2Fast4U1DAY; 01-15-2014 at 02:25 PM.
2Fast4U1DAY is offline   Reply With Quote
Old 01-15-2014, 10:48 PM   #8
BeastianSTI
Scooby Specialist
 
Member#: 310506
Join Date: Feb 2012
Chapter/Region: South East
Location: Florida
Vehicle:
2005 WRX STi
CGM

Default

Quote:
Originally Posted by 2Fast4U1DAY View Post
Always. Ive torn apart several blocks that have been OOR (out of round) pretty bad and some even had completely misaligned bores. Heck ive pulled a few "newer" (less than 20k miles) cases that were off by as much as .004 Having an improperly shaped or sized journal or bore can cause oiling issues and spun bearings. I have seen misaligned crank bores even snap a crank. As for relying on the machine shop to tell you what size pistons pistons you need, I would definitely follow their advice. You have no idea if the block is scored or how much wear has actually taken place unless you measure for yourself with a Dial bore gauge (not a cheapo one either). Judging by your questions im assuming you dont have mics or bore gauges so yes I would not divert from what you builder says. However, Rings should come with the piston set, and unless you are going over a 100 mm bore stock gasket will do unless you need a specific thickness due to machining the deck of the block or heads or both As for CR I would stay 8.2 for safety. At 8.9 you raise the risk of knock on pump due to more heat generated from compression, and pump fuels inconsistencies. If you were running E or meth or Racegas then you can get away with the higher compression as the higher octane will help combat knock, due to their higher resistance to detonation
So whAt exactly is that procedure called ? Boring the main journal ? And how much does that normally cost to have done ?
BeastianSTI is offline   Reply With Quote
Old 01-16-2014, 09:18 AM   #9
2Fast4U1DAY
Scooby Specialist
 
Member#: 250152
Join Date: Jun 2010
Chapter/Region: MAIC
Location: Pennsylvania
Vehicle:
2006 WRX Limited
OBP

Default

Quote:
Originally Posted by BeastianSTI View Post

So whAt exactly is that procedure called ? Boring the main journal ? And how much does that normally cost to have done ?
It is called align (or line) boring/honing. Ive never had one align honed to have a price point but Ive heard as much as 300-600. Just depends on the shop.
I just got a new case and crank when I did my build because I had partially spun a main bearing (oil pickup failure) and I knew it would be worse than just the 134k normal wear on the engine plus I was in sort of a hurry to get my car back on the road.
2Fast4U1DAY is offline   Reply With Quote
Old 01-16-2014, 09:25 AM   #10
o4wrxwagon
Scooby Newbie
 
Member#: 213945
Join Date: Jun 2009
Location: Rochester NY
Vehicle:
04 wrx wagon
PSM

Default

To have a shop do all that, it may be cheaper to just pick up a new heat treated crank off ebay thats already to spec and balanced. Theres a seller on there that sells OEM Subaru cranks for 325 shipped. Do that, new bearings and pistons and call it a day. I went with King Bearings for my build. ACL had mixed reviews on them. If your bearings in there now aren't scored or scuffed even, I would say you're probably fine. You may as well upgrade as much as you can.
o4wrxwagon is offline   Reply With Quote
Old 01-16-2014, 09:37 AM   #11
o4wrxwagon
Scooby Newbie
 
Member#: 213945
Join Date: Jun 2009
Location: Rochester NY
Vehicle:
04 wrx wagon
PSM

Default

The block should also be stamped some where on there AB AB or sometimes AA AA or even BB BB. This is your piston size. A is slightly smaller? than B. You would have to double check that. Manley sells drop in pistons that are sized by A and B. I think A, the specs are 3.170-3.174 and B is 3.175 to 3.179.

As long as the cylinders measure out to with in these, they should be able to do a finish hone on it so your rings will set. Double check thoses numbers though. I have them on my phone some where but I can't look at this time.
o4wrxwagon is offline   Reply With Quote
Old 01-16-2014, 10:28 AM   #12
some dude
Scooby Specialist
 
Member#: 100300
Join Date: Nov 2005
Chapter/Region: MWSOC
Location: MIC|-|IG/\N
Vehicle:
06 WRX
CGM

Default

I too have read ACL bearings have been questionable lately. Perhaps their RACE bearings are what ppl r using currently. King might b another to look at.

I say, keep compression low. Raising compression is more of a naturally aspirated thing. You have a turbo so no need to risk det. By bumping up compression.
some dude is offline   Reply With Quote
Old 01-16-2014, 11:46 AM   #13
BeastianSTI
Scooby Specialist
 
Member#: 310506
Join Date: Feb 2012
Chapter/Region: South East
Location: Florida
Vehicle:
2005 WRX STi
CGM

Default

Hmm... Yeah, i'll take a look into other bearing options for sure.
Keeping compression @ 8.2:1.

Wow, that's really steep to have that done. I'll have em measure out the crank, and if it's wacky, then buy a new one I suppose. Engine has a cracked ringland right now, so it's prolly going to need a rebore for sure.
BeastianSTI is offline   Reply With Quote
Old 01-16-2014, 11:47 AM   #14
2Fast4U1DAY
Scooby Specialist
 
Member#: 250152
Join Date: Jun 2010
Chapter/Region: MAIC
Location: Pennsylvania
Vehicle:
2006 WRX Limited
OBP

Default

Quote:
Originally Posted by o4wrxwagon View Post
The block should also be stamped some where on there AB AB or sometimes AA AA or even BB BB. This is your piston size. A is slightly smaller? than B. You would have to double check that. Manley sells drop in pistons that are sized by A and B. I think A, the specs are 3.170-3.174 and B is 3.175 to 3.179.

As long as the cylinders measure out to with in these, they should be able to do a finish hone on it so your rings will set. Double check thoses numbers though. I have them on my phone some where but I can't look at this time.
While this may be true the op needs to find out what his bores sit at currently and their condition. Without this buying pistons is pissing in the wind
2Fast4U1DAY is offline   Reply With Quote
Old 01-16-2014, 11:50 AM   #15
2Fast4U1DAY
Scooby Specialist
 
Member#: 250152
Join Date: Jun 2010
Chapter/Region: MAIC
Location: Pennsylvania
Vehicle:
2006 WRX Limited
OBP

Default

Quote:
Originally Posted by BeastianSTI View Post
Hmm... Yeah, i'll take a look into other bearing options for sure.
Keeping compression @ 8.2:1.

Wow, that's really steep to have that done. I'll have em measure out the crank, and if it's wacky, then buy a new one I suppose. Engine has a cracked ringland right now, so it's prolly going to need a rebore for sure.
No drop ins for you :-/. See if you can get away with 99.75 by having your machine shop inspect the case... if not I would try to get another case as to preserve as much cylinder wall thickness as possible
2Fast4U1DAY is offline   Reply With Quote
Old 01-16-2014, 01:07 PM   #16
BeastianSTI
Scooby Specialist
 
Member#: 310506
Join Date: Feb 2012
Chapter/Region: South East
Location: Florida
Vehicle:
2005 WRX STi
CGM

Default

I figured I wouldn't be able to drop one in. I want a build that will last for a while. I suppose I wont need to buy the electronic bore gauge / micrometers, and can instead trust the machine shop for measurements?
BeastianSTI is offline   Reply With Quote
Old 01-16-2014, 01:30 PM   #17
Juks
Scooby Specialist
 
Member#: 108163
Join Date: Feb 2006
Location: Twin Cities, MN
Vehicle:
2005 STI
OBP

Default

Ideally you could go with 99.75mm, but 100mm is a also a pretty common size, I know it takes away cylinder wall thickness, but at 400whp I think you'd be ok. Just bring the pistons in with the block for the bore/hone and they'll match each piston to each cylinder bore. You should get the pistons back numbered so you know which one goes where.
Juks is offline   Reply With Quote
Old 01-17-2014, 02:16 PM   #18
BeastianSTI
Scooby Specialist
 
Member#: 310506
Join Date: Feb 2012
Chapter/Region: South East
Location: Florida
Vehicle:
2005 WRX STi
CGM

Default

Ok - so is it the crankshaft itself that gets out of spec, or the journals in the block that the main bearings set into?
BeastianSTI is offline   Reply With Quote
Old 01-17-2014, 02:26 PM   #19
Barney145
Scooby Newbie
 
Member#: 376219
Join Date: Dec 2013
Default

Quote:
Originally Posted by BeastianSTI View Post
Ok - so is it the crankshaft itself that gets out of spec, or the journals in the block that the main bearings set into?
The mainline will grow in diameter and/or get out of alignment on a block that's had lots of boost or big horsepower in general. I know one shop that charges $400 to line bore.
Barney145 is offline   Reply With Quote
Old 01-17-2014, 02:37 PM   #20
BeastianSTI
Scooby Specialist
 
Member#: 310506
Join Date: Feb 2012
Chapter/Region: South East
Location: Florida
Vehicle:
2005 WRX STi
CGM

Default

aka half the price of a whole new case, huh? For the amount of machining that is going to need to be done to clean the block, deck it, re-bore and check the mainline, I could get a whole new case and put stock bore forged pistons in, it sound like.
BeastianSTI is offline   Reply With Quote
Old 01-17-2014, 05:28 PM   #21
2Fast4U1DAY
Scooby Specialist
 
Member#: 250152
Join Date: Jun 2010
Chapter/Region: MAIC
Location: Pennsylvania
Vehicle:
2006 WRX Limited
OBP

Default

Quote:
Originally Posted by BeastianSTI View Post
aka half the price of a whole new case, huh? For the amount of machining that is going to need to be done to clean the block, deck it, re-bore and check the mainline, I could get a whole new case and put stock bore forged pistons in, it sound like.
This is what most do. Granted a brand new case is over a grand last I checked so you could save a little money, its just not as significant as on other platforms
2Fast4U1DAY is offline   Reply With Quote
Old 01-22-2014, 12:08 AM   #22
BeastianSTI
Scooby Specialist
 
Member#: 310506
Join Date: Feb 2012
Chapter/Region: South East
Location: Florida
Vehicle:
2005 WRX STi
CGM

Default

So... I only measured compression on 3 cylinders,... 150... 140....80! Looks like I'm gonna need to rebuild it for sure.
BeastianSTI is offline   Reply With Quote
Old 01-22-2014, 03:08 AM   #23
2Fast4U1DAY
Scooby Specialist
 
Member#: 250152
Join Date: Jun 2010
Chapter/Region: MAIC
Location: Pennsylvania
Vehicle:
2006 WRX Limited
OBP

Default

Quote:
Originally Posted by BeastianSTI View Post
So... I only measured compression on 3 cylinders,... 150... 140....80! Looks like I'm gonna need to rebuild it for sure.
Yup shes toast.
2Fast4U1DAY is offline   Reply With Quote
Old 01-28-2014, 11:00 PM   #24
BeastianSTI
Scooby Specialist
 
Member#: 310506
Join Date: Feb 2012
Chapter/Region: South East
Location: Florida
Vehicle:
2005 WRX STi
CGM

Default

Hey guys,

Do I need new head bolts if I pull the block apart, or can I keep the ones that are in there ( stock @ 100k)?
BeastianSTI is offline   Reply With Quote
Old 01-29-2014, 10:37 AM   #25
BeastianSTI
Scooby Specialist
 
Member#: 310506
Join Date: Feb 2012
Chapter/Region: South East
Location: Florida
Vehicle:
2005 WRX STi
CGM

Default

Bumpppp. Anyone ?
BeastianSTI is offline   Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump

All times are GMT -4. The time now is 06:53 AM.


Powered by vBulletin® Version 3.7.0
Copyright ©2000 - 2024, Jelsoft Enterprises Ltd.
Powered by Searchlight © 2024 Axivo Inc.
Copyright ©1999 - 2019, North American Subaru Impreza Owners Club, Inc.

As an Amazon Associate I earn from qualifying purchases.

When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission
Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.