legacycentral bbs

I'll probably stay in the stock specs, so i'll be able to get stock rings and stuff.

What bore will you get ? 100mm ?

Probably, if not a little more.

Stock specs of what exactly? 9.69 9.96 or 9.2?

I worry though, do you guys remember that the turbo 2.2 block supposedly had a liner composed of a different metal forged into the cylinder walls? I thought I remember reading that. If I bore it out that will be lost.

What do you think about runnig the cylinder walls out of the aluminum?

stock 96.9mm. will have an exact measurement when i'll get the block at a pro. shop to get it cleaned and "refreshed"

i remember reading that too, and you can see it on that picture (look at the right) :
http://themorg.dyndns.org/misc/158-5854_IMG.JPG

i'll clean it tomorrow and take a pic so you'll be able to see the sleeve better.

i'm not sure if it's a good idea to run it on the aluminum :\ lower the overbore, raise the boost ! hehe

As promised, here are the pics..
it's a bit different than what i think.

full album + hires pics (..get original uploaded picture link under each photo)
http://public.fotki.com/morgie/morgie/o ... e_sleeves/

First, the sleeve dont go to the top. it stops at about 3/16"



looking at the piston pins removal holes, you can see the thickness of the sleeve. Also in the 1/8" to 3/16" range.

Just went into a machine shop specialised in rebuilding engines and heads, and it's possible to bore the cylinders to 99.9mm (or 100mm).

BUT, you end up removing 50% of the thickness of the sleeve.

There is material enought to do this overbore, but what will be the end result ? Unknown.. will 1/16" be thick enought ? (+ the alluminium layer wich is about 3/16")

.. what do you think ? 99.9mm forged pistons might interest me and my friend 2.5l is good ! hehe

A guy on the Montreal-Subaru-Club forum answered with some interesting points to check .. I'll translate for you :

DON'T DO THAT.....not good... and here's some reasong....

1- On what will your gasket sit and seal ? the max overbore for that block is .5mm

2- Who told you that the sleeve was a constant tickness cylinder ? I personnaly don't know at all about that.

3- If it overheat, the sleeve will probably twist.

4- There is surely tons of other reasons not to do that.

humm. better verify that well before doing that overbore.

For the gasket question, if we limit our overbore to 99.6mm, we could use the DOHC 2.5l head gaskets.

for the other points.. i have no answers. not yet..

I've just called the technical director at my dealership, and he sais about the same thing than in the post above..

1 - the max overbore is 0.50mm, pretty far from our wanted 3mm
2 - the sleeve will be to thin, and will be subject to overheating. piston will "slap" (kekling kekling.. hehe)
3 - the sleeve may twist under heat.

3mm overbore will make a very powerfull engine block.. but not for a long time

Although I want to be safe I take both of those responses as being worth little.

"1- On what will your gasket sit and seal ? the max overbore for that block is .5mm"

Qouted spec for dealer safety before replacing the block. We all know these figures are VERY safe. Do these people realize that the gasket doesnt exactly match the bore of the engine there is empty space. The 2.5 gasket would be plenty big anyways so its not an issue

"2- Who told you that the sleeve was a constant tickness cylinder ? "
Just from what I understand it is infinitely easier to produce a constant diameter cylinder than some stepped or "curved" item. Why would they do it otherwise?!

"3- If it overheat, the sleeve will probably twist."
I thought I read the sleeve was cast in place. Sure it is disimilar metal but this isnt the standard insert like on a deisel!

"1 - the max overbore is 0.50mm, pretty far from our wanted 3mm"
Again dealer specs for safety. Lets just say that the sleave isnt an issue for the moment. The remaining wall thickness is still thick

I still dont agree with this, especially since large overbore subarus already exist! We just need to get in contact with those people.

Knowing how I feel, I think you are right that increasing the bore may be a problem so Im now getting my tech contacts to look into it

Rod G had his EJ22T motor overbored to a 2.4 (don't know the actual overbore) I believe.....someone he was talking to was worried about this....he didn't seem to think it was an issue.

I'll email him this thread and let him respond.

Josh, are you sure it isn't stroked to 2.4?

-Brian

A guy on the MSC's had written some interesting stuff about the casting process of the sleeve .. i'll translate and post them later (i'm at school now )

I said that the Sleeve of the EJ22T is casted into the engine, not like some other engines wich have their sleeves press-fit into the engine after casting.

here is his reply :

Simon wrote:You’re right Morgie, some engines have their sleeve casted with the block. I saw that in Japan. They put a groove on the exterior side of the sleeve (towards aluminum) to make sure it does not move from there. Apparently, it is a less expensive procedure (no need for tolerance checks before press fitting the sleeve (other process) ). The problem of this process: once the sleeve is worn out, the engine can not be restored (cost less to change completely the block vs trying to replace de sleeve).

Morgie wrote:Ok, so if subaru used that process, the issue of the sleeve twisting and moving is not valid !

Simon wrote:It’s certain that if subaru employ this type of casting, the sleeve will not move of. But the sleeve can / could still be deformed by heat if it is too thin. Certain company adopts others strategies. Instead of a simple groove (or rib) on the sleeve, it is a complete pattern of ribs that are embedded in the block to allow a greater surface of contact between the steel and the aluminum (better transfer of heat). However, it is not subaru who will tell you how their castings are made. You will have to talk to someone who has previously cut open a block to know.

Simon wrote:You want my personal opinion: unless speaking to someone who has previously exceeded the oversize limits of Subaru, and done some real good tests (not just 5 minutes on a dyno), I would go with the popular opinion (Morgie Insert : Wich is: not to do that, stay with the stock Bore 96.9mm). It’s very frustrating to scrap a project because we wanted to exceed the limits ( or, go too far).

He's quite right with is last personal opinion... since this car will be my daily driver, i want it to be the most reliable possible.

When Paeco did my block, we went with a 1/2" stroke with a .040" overbore (it will take a .060" bore safely according to them.) I know that I-Speed`s engine builder was a little leery about my overbore but we`ll see fairly soon. He sleeves all his 2.4, 2.6 and 2.8 blocks so that`s a possibility, too. Go to www.i-speedusa.com and check it out. If I happen to have any problems, I`ll go with sleeves as a final solution. I know I`ve been promising that my engine project would be completed before, but if something can go wrong, it will go wrong!!! Keep the faith--I am.---Rod

morgie:Sounds good to me.

What do you think is a good compromise before sleaving? If a 3mm overbore results in 50% reduction and the allowed (ultra safe IMO) is .5 then would you think that 1.0 over a good compromise? This would result 2258 instead of 2212 normally present. 46cc more displacement per cycle which also changes compression and increases oversqaure of the engine.

Subie_do: what does 1/2" stroke mean?

Subie_Do : Your 0.04" overbore correspond to +1mm overbore. Ciper is talking about +3mm overbore (+1/8" overbore).

i think is a bit too much (for me) but could be interesting hehe

Funny, I didnt read his post entirely. INCHES!

So I suggested a 1mm overbore in my latest post which happens to be exactly what subie_do did

So a 1.5mm overbore is save according to them? Results in 2281 with stock stroke, 69cc more.

will that 69cc increase do such a big difference that will justify the "raised" damage risks, and the 35$*4 = 140$ the machineshop is asking for overboring the cylinders ?

i bet +1psi of boost is more cost-efficient (or.. a more cost-wise solution ? humm)

or a waterspray kit.. or ... ehhe

Awesome thread guys.
I haven't been around of late since I quit my job and don't have my own internet. I am glad to hear about the head/manifold stuff getting sorted out, since I took possession of my STiv6 manifold this weekend. In the research process, I discovered that USDM heads use the same cores as the JDM v5 and v6 STi's. So I am now seriously considering just getting a cheap USDM head and slapping it on instead of the SOHC EJ25 heads I planned on previous. Especially since I got intake piping,injectors,plug wires and full engine harness with it. I may just rewire and run this thing with a WRX OBD-II ECU...

I will be eagerly reading how this cylinder bore stuff plays out. And I will definitely have to figure out the head gasket/CR issues since I want to use a VF-28 and it maxes out at 18psi...

the guys over here just get the JDM MY94 wrx motor stroke it to 2.4ltrs, then fit all forged pistons and rods and stick the heads back on, this way its a closed deck block hence less cylinder wall flex under high boost.

I'll probably not play with overbore.

I'll simply get a set of custom forged pistons to get the CR back to 8.5:1 or 9:1

(2.2l pistons has a 28cc inverted dome. with 9-11cc inverted dome, you get close to 9:1)

So I now know that I-speed and TWE both overbore the engines then insert a sleeve. From what I have read this doesnt look to be that expensive......

Also 99.6 and 100 sized pistons are fairly common....

RossPistons, 424$ for a set of 4 forged pistons..

that will be my solution

I used Arias (or Paeco did) for my forged pistons. They now have the castings for the EJ22T and can produce pistons in any format and CR (mine are 9:1) in a reasonable amount of time. I`d suggest Arias as Tony Rigoli and EasyStreet both use them exclusively; look at the performance they achieve w/o piston problems. Just a thought---Rod

sweet, i'll take a look ! thanx
http://www.ariaspistons.com/

ciper wrote:So I now know that I-speed and TWE both overbore the engines then insert a sleeve. From what I have read this doesnt look to be that expensive......

Also 99.6 and 100 sized pistons are fairly common....

This is why I wasn't to concerned about the boring portion of this discussion. I will in all likelyhood be sending my block to TWE to have this work done. I wanted to use my EJ257 pistons in there, but I too want to keep the CR up near stock and more and more it looks like I will get some TWE pistons put in there when they clean up the block(blueprinting with stock internals) and overbore it...Of course this means if someone is looking for EJ257 pistons in say, 6 months, they should get in touch...