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Old 04-12-2009, 12:59 PM   #1
Harsesis
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Default 2.0 to 2.5l block swap questions

I have an 04 wrx that has developed a rod knock. I am looking at putting in the 2.5l sti block in it's place, and looking for tip and tricks for the swap.

Current mods on the 2.0l are vf39, sti intercooler, aem cold air intake, turbo back exaust, pinky injectors, cobb accessport stage 3 map. Will my current map work swapping to the 2.5L sti block. It appears that my compression will be raised to around 8.8, from stock. I don't know/feel that this will be an issue since I am only putting 17-17.5psi of boost with the current map.

Which headgaskets need to be used? The stock 2.0L or the stock sti headgaskets?

Any help would be appreaciated.

BTW vehicle currently has right at 100k on the set-up(stock modded set-up)

BTW I work at a subaru dealer and want to stick to stock parts for the swap due to warranty and ease of getting parts.

Thanks
Joe
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Old 04-12-2009, 01:09 PM   #2
Uncle Scotty
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d0000000000d

this whole thing is covered here somewhere

find it and read it
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Old 04-12-2009, 01:17 PM   #3
WRXINTX
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Quote:
Originally Posted by Harsesis View Post
I have an 04 wrx that has developed a rod knock. I am looking at putting in the 2.5l sti block in it's place, and looking for tip and tricks for the swap.

Current mods on the 2.0l are vf39, sti intercooler, aem cold air intake, turbo back exaust, pinky injectors, cobb accessport stage 3 map. Will my current map work swapping to the 2.5L sti block. It appears that my compression will be raised to around 8.8, from stock. I don't know/feel that this will be an issue since I am only putting 17-17.5psi of boost with the current map.

Which headgaskets need to be used? The stock 2.0L or the stock sti headgaskets?

Any help would be appreaciated.

BTW vehicle currently has right at 100k on the set-up(stock modded set-up)

BTW I work at a subaru dealer and want to stick to stock parts for the swap due to warranty and ease of getting parts.

Thanks
Joe


If you work at a dealership, you should probably already know that Subaru will not warranty a 2.5L shortblock when installed into the place where a 2.0L was.


Use stock STI 2.5L head gaskets and all other stock 2.0L parts will bolt on to the 2.5L engine.


And no, your current tune will not be anywhere close for a hybrid swap engine block.
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Old 04-12-2009, 03:10 PM   #4
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stock sti headgaskets will have high compression.
most shops recommend using a thicker headgasket like cometic
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Old 04-12-2009, 07:10 PM   #5
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I work at a dealership and know what I can and can not get/have warranted as I have been working on Subarus for 20 years. I just haven't been through the hybrid swap yet and was looking for answers not a pissing war.

I have searched and found several different answers on the headgaskets ranging from the stock 2.0 to the 257 to the original 2.5L cometic style gaskets. I was looking to see if this has been setteled to date. Also as far as the mapping goes I was wondering if the stage 3 would be ok.
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Old 04-12-2009, 07:33 PM   #6
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if you worked for subaru for 20 years why dont you already know all the answers
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Old 04-12-2009, 07:36 PM   #7
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Maybe you missed this part
Quote:
I just haven't been through the hybrid swap yet and was looking for answers not a pissing war.
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Old 04-12-2009, 08:23 PM   #8
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Dont you think it would be much more easy to just answer the questions asked? Unless you have a car of your own we don't get many chances to figure out all these hybrid motor questions at the dealership. This is the whole reason for this section of the forum.

Last edited by 98foreza; 04-12-2009 at 08:55 PM.
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Old 04-13-2009, 10:54 AM   #9
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Quote:
Originally Posted by eurynome View Post
if you worked for subaru for 20 years why dont you already know all the answers

ppl w/ comments like this need to hit up a teen chat room ?
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Old 04-13-2009, 12:09 PM   #10
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Amen to that
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Old 04-13-2009, 11:54 PM   #11
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Honesly eurynome, don't be a prick. I am putting looking at putting a Legacy GT 2.5 in my wrx and I have owned a salvage yard for many years... I would like to know the answer too, and I don't know everything about the swap. Obviously you don't either or you would have been nice enough to help.

Demon... know the cheapest place to find a cometic?

Does anyone know off the top of their head the difference in compression between a stock STI and a cometic?
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Old 04-13-2009, 11:57 PM   #12
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Also, now that I look at it... where does the STI get the extra 50hp over the Legacy GT? Same block and heads according to my interchange...
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Old 04-14-2009, 05:54 PM   #13
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The lagacy is the exact same setup other than the tuning. I believe this where
you lose the extra power. It will come to life with a tuner
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Old 04-14-2009, 05:55 PM   #14
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So I guess no one is going to set us straight o this head gasket fiasco?
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Old 04-19-2009, 02:59 AM   #15
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I'm going through this same issue right now with my 03 rex. And the answer on the head gasket is a 1.5mm gasket. And you will need a new tune. From what I've been told, the torque will be higher. The price isn't that much more either.
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Old 04-21-2009, 03:13 AM   #16
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I'm interested in this too!!... I did the 2.0 heads on a stock ej257 block with stock STi gaskets and would love to know the Compression Ratio as well. This will help pe to decide what turbo to put in.
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Old 04-21-2009, 04:14 AM   #17
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Whoa so much mis-information and information all wrapped together!

Lets get everyone on the same page here, they hybrid swap (basic) is either a ej257/ej255 dropped into a wrx (2.0) power train, retaining the wrx's heads ect. There have been swaps done with using different blocks (22t, ej251) which you can find good write up's on rs25.com. Ok now that being said on to some minor flaming, and not to be a dick but some is due.

Search people, everyone says it but honestly **** like this is why. Everything you could possibly want to know is documented on this swap, all you have to do is dig a bit for it, honestly EVERYTHING is documented.

Now that being said find a compression calculator to adjust your cr back closer to stock level's if you arn't going to tune it yourself or take it to a tuner... just an fyi, don't expect the block to last without a proper tune my man, when you add .5l of displacement you ecu can't learn around it, some people have run without tune's however if it was my 2k sb there is no way in hell i'd ever ever ever run without a tune.. but thats me.

So, to answer some of your questions,
Head Gaskets are based off of bore, being a mechanic this seems like a no brainer to me, but i won't tell you how to fix subaru's and you won't tell me how to do my job! , Everything else will bolt right up, imo drop in a 12mil pump and shim it!

1. RESEARCH!@
1.5 Drop in the SB
2. Get a tune
3. Enjoy

And i plan on doing something similar to what fujik did, this kid has done more homework than i probably ever will, i'm impressed!

http://www.rs25.com/forums/showthrea...ght=2.5+hybrid
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Old 04-22-2009, 02:45 PM   #18
B-Kerr
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907Bum: We appreciate any and all input. However, as you said, there is always a wealth of information and MIS-information available. This why we ask questions. We know that a 2.5 gasket is needed... the questions is Cometic (a/m) vs STI (stock). For DSMs, I have heard of Cometics slipping is head is not prepared absolutely to a certain mil. And C/R is an issue of course.

There is plenty of info on NASIOC, but some of it is out-of-date. For example, I bought my car new in 02. I am running a VF22 and a Unichip! This is an antiquated set-up today, but you can still find info on it. A person would be crazy to go this route today if they stumbled upon the post... but it could happen. Regardless, I am happy with my 330 engine hp! An STI gasket was probably the best bet for this swap 2 years ago - is it now? Are better things out there?

As for the research, I search until my eyes hurt, but I do not always find what I need - even on here. Sometimes its easier to ask; that's why we are here - to help one another modify and destroy perfectly good means of transportation! I still have not found a definite on which axles to use in my 05 LGT tranny to 02 WRX swap and I have search for a week! Guess what I did today - I posted and asked for input.

I don't think anyone with a brain would modify any car without a tune, but it never hurts to say it as you did (and I definitely agree). Which is a entirely different ??? What tune to use... ECUtek? Utec? AEM? Unichip (doubt it)? Hydra? ROM Raider (which I am currently looking into...)? You can research til you go crazy. Sometimes however, you can contact a real person, not just an old post, that is running a set-up and get realtime answers.

1. Everyone should know to search; but we get overwhelmed.
2. Old questions get, yes, OLD.
3. Old information may be bad information.
4. TUNE YOUR ENGINE!
5. Let's all helps each other out - have to beat the DSMs!
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Old 04-24-2009, 01:54 PM   #19
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I recently contacted cometic about the headgasket question for a 255 hybrid I will be putting together and they told me they have a big bore 2.0 gasket with multiple thickness options.
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Old 04-24-2009, 08:16 PM   #20
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Hey! useful information thank you
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Old 04-24-2009, 11:32 PM   #21
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Here is a copy from their response:

Actually you would need to run the EJ20 head gasket with a larger bore in it. It would be our part number: H1633SP2XXXS. The XXX indicates the thickness, so for a .040" thick gasket, the part number would be H1633SP2040S.
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Old 04-25-2009, 10:01 AM   #22
B-Kerr
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Very cool to know! Hmmm, so keep a smaller turbo and go thinner gasket, or go bigger turbo and thicker gasket I suppose.
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Old 04-30-2009, 08:48 PM   #23
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Ok swap performed using the ej25dohc headgaskets(95-early99). After being intouch with Cobb and then being refered to Cobb Tuning of Plano TX. The answer to the question is yes the vf39 stage 3 tune would be adequate to drive on. Yes it will need to be tuned, but it can be driven on this map. The recommended to put 1000-1500 miles on it before taking it there for the tune.
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Old 05-01-2009, 08:37 AM   #24
xrturbo
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Sweet!! How does it run? What did you do for the dual/single breather issue? Catch can? Keep us posted on how it works!!
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