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Swapping ej22 with ej25 97 Impreza outback


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I have a 1997 Subaru Impreza outback and Im wanting to swap a 2.5 DOHC engine into it. My 2 main goals are power and reliability. I was wondering if someone knew which years and models I could get one from that would require little modification. It does have EGR. 

Also does anyone know how to fix the "fuel temperature sensor" fault code? I've replaced the fuel pump!?!? Car will just lag out like it ran out of gas but as soon as I put it in neutral it starts right back up but it dies quite a few more times until it warms up.

 

 

Edited by Caden
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There’s like 13 different ways to do this  and you haven’t given us any background.  Do you want power or cheap or easy or reliability or what percent mixture of those? Each of those is a huge determining factor in how best to proceed. I’d want reliability first and ensure I’m getting new headgajseys on any EJ25 swap  

Buy a newer (and better) phase II Subaru EJ25 OEM block for $2,000 and bolt your Impreza heads and intake to it.  Then there’s guaranteed fitment with no questions or concerns, new headgaskets, brand new block with 36,000 mile 36 month warranty.  They probably won’t honor it on a swap depending on your relationship with your dealer.

If you want the plug and play used long block option then get the matching exhaust manifold and EGr configuration from:

Any 1996-1998 EJ25

Any 1999 Legacy or Outback EJ25 (not a 99 forester or Impreza RS)

You never said if your Impreza has EGR.  If you don’t care about check engine lights or can do a little extra work around you can ignore EGR and make any EJ25 work.  All the engine I listed plug in and run the exact same in your car even if you ignore EGr. It’s just CEL and emissions and there’s easy work around b

If you bolt your Impreza heads to an EJ25 block use 99 Forster/Impreza or 2000-2004 EJ25 block (phase II) I mentioned earlier. You’ll get a compression and HP bump doing this over just using an entire EJ25.  And you don’t get tjose bizarre EJ25 DOhC pistons that stick out about the block plane and seem worse than later block variations.  

You may need to run premium gas but I’m unsure which combos end up needing jt snd which don’t. Even early 96 complete EJ25s sometimes need premium gas too. I think 1996s. 

 

 

Edited by idosubaru
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5 hours ago, idosubaru said:

There’s like 13 different ways to do this  and you haven’t given us any background.  Do you want power or cheap or easy or reliability or what percent mixture of those? Each of those is a huge determining factor in how best to proceed. I’d want reliability first and ensure I’m getting new headgajseys on any EJ25 swap  

Buy a newer (and better) phase II Subaru EJ25 OEM block for $2,000 and bolt your Impreza heads and intake to it.  Then there’s guaranteed fitment with no questions or concerns, new headgaskets, brand new block with 36,000 mile 36 month warranty.  They probably won’t honor it on a swap depending on your relationship with your dealer.

If you want the plug and play used long block option then get the matching exhaust manifold and EGr configuration from:

Any 1996-1998 EJ25

Any 1999 Legacy or Outback EJ25 (not a 99 forester or Impreza RS)

You never said if your Impreza has EGR.  If you don’t care about check engine lights or can do a little extra work around you can ignore EGR and make any EJ25 work.  All the engine I listed plug in and run the exact same in your car even if you ignore EGr. It’s just CEL and emissions and there’s easy work around b

If you bolt your Impreza heads to an EJ25 block use 99 Forster/Impreza or 2000-2004 EJ25 block (phase II) I mentioned earlier. You’ll get a compression and HP bump doing this over just using an entire EJ25.  And you don’t get tjose bizarre EJ25 DOhC pistons that stick out about the block plane and seem worse than later block variations.  

You may need to run premium gas but I’m unsure which combos end up needing jt snd which don’t. Even early 96 complete EJ25s sometimes need premium gas too. I think 1996s. 

 

 

Thank you for your reply it was very helpful I have updated my post with some more information

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If you're trying to do this as cheap as possible:
$200-$300 for any of the various cheapest 2000-2004 short blocks on www.car-part.com, or look locally on craigslist/facebook for a wrecked car, ebay, etc.
$150 for Subaru head gaskets
$100 for a new Subaru timing belt and lower cogged idler.

Resurface the ej22 heads (you can even do it yourself it's really easy).  No need for a full valve job. 
Install your ej22 heads onto the EJ25 block properly (clean cams, heads, head bolts, and head bolt holes, lubricate head bolts, torque properly)

You have an EJ25 for about $500 in parts that's way better than any EJ25D option.  It drops in and plugs and plays without any electronics or other work.  It's super simple. 


Some  notes: 
You have to keep searching for a good block - just keep calling all the listings until you find a good block.
Also use car-parts.com to search for 2001 auto and manual and 2003 outback - they're all the same eventhough they list them separately. 

Or instead of getting a used one buy a brand new block with a warranty from Subaru for $2,000 or these guys for $1,200:
https://sunwestautoinc.com/product/subaru-ej25-short-block-2-5l-sohc-1996-2011/

You should also install new subaru timing belt and all new pulleys.  $150-$250 for 2 pulleys, belt, tensioner.  But the timing belt and lower toothed/cogged idler is the bare minimum as they're by far the most likely to fail and are a non negotiable to replace in a new expensive enngine/repair.  But I'd do all the pulleys.

 

 

 

 

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my personal opinion on the pulleys.. do them all and be done with it for 100K

yes, the cogged idler is the absolute bare minimum if you are on a super tight budget, but if you are that far in, and you can afford to, it is worth doing it all and not having to worry about it.

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  • 3 weeks later...
Posted (edited)

Thank you a lot Idosubaru and heartless and 1 lucky texan and imdew. So if I were to get the 2.5 block brand new and put the 2.2 head on what website or where do you guys suggest I get performance parts such as, bigger cams, bigger injectors, forged pistons..etc or does the enhanced 2.5 blocks from sunwest come with all of that? Or should I still put better internals in the 2.5 enhanced block if I got one?

Edited by Caden
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you dont seem to understand.. you cant just buy stuff off the shelf for these like you can a SB chevy or whatnot, there is no after market for these, to be honest.

the WRX/STI line is about as high performance as it gets, and if that is what you want, then that is what you should buy. you are not going to make a bog standard, NA 2.2 or 2.5 into a power house.

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Well I I did not know that, but what if my goal is to turbo my 2.5 sohc? Does that open up any other options? Sorry I'm new to Subarus I appreciate all of you guys' information

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17 hours ago, Caden said:

Thank you a lot Idosubaru and heartless and 1 lucky texan and imdew. So if I were to get the 2.5 block brand new and put the 2.2 head on what website or where do you guys suggest I get performance parts such as, bigger cams, bigger injectors, forged pistons..etc or does the enhanced 2.5 blocks from sunwest come with all of that? Or should I still put better internals in the 2.5 enhanced block if I got one?

"Put better internals" - 

Are you doing all the work?  If labor is free (which it won't be):  It'll cost $5k for engine, $1k+ for turbo/downpipe, $1k for controller, plus supporting gaskets, fluids.  The questions being asked here don't sound like they're coming from somone with the experience or technical understanding to do this kind of work. 

If paying someone else:  $10k+.   In that case you need to ask them questions as they'll have they're own preferred methods/sources/pricing.

Crawford sells built turbo blocks and parts.  https://crawfordperformance.com/collections/crawford-built-subaru-short-blocks

Or you can try to ghetto build it with rising rate fuel pressure regulators and an SPFI and blow up a few blocks to learn the ropes. 

 

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Posted (edited)

swapping engine/drivetrain from a wrecked WRX is the 'best' approach for what you propose - dig around at NASIOC.com for examples of swaps. Very time/labor/$$$ intensive

 

you CAN make the present car more fun to toss around corners..

Edited by 1 Lucky Texan
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I have rebuilt an engine for and I have some mechanical knowledge I'm just not familiar with Subarus and the compatibility between each part. I will be doing all of the labor my self. I'm trying I'm trying to figure out which manual transmission and turbo I should use with the 2.5 sohc and 2.2 heads

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Posted (edited)

There’s so many different ways to do this - it’s almost infinite. It’s hard to say much with confusing general questions. 

Whatever you do - Get a new Subaru turbo only. Or equivalent OEM supplier.

The choice of block and internals and transmission depends how much power you’re aiming for, how much you’re willing to spend, and *how long you want the engine to last* - which everyone says they want but actually spend no time considering.

First  you wanted a 97 DOHC which isn’t turbo, nor ideal.  Then you wanted forged internals which isn’t necessary or beneficial on a non turbo. Then later you say turbo.  You also said “little modification” but now you’re mentioning turbos with forged internals that you’ll be installing yourself - which will require rewiring and controllers with extensive cross member and exhaust overhaul and/or cutting/welding. Then you mentioned upgraded transmission. That’s the opposite of “little modification”  

price tag of your implied goals has ranged from $500 to $15,000 depending how we interpret it. 

Id work on narrowing down your goals here to something chewable and manageable.

One of the best subaru builders is in your state, Superior Soobie in Oregon could do it for you.  You’ll get top notch work and more importantly it’ll last. 

Edited by idosubaru
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You could also price it all out and see for yourself - are you okay with $5k-$10k in costs even if you’re doing all the labor? If so then maybe paying superior to do it is a much better option.  Not because you can’t but because theyre that good.

If cost does have a lid then look at your list and ask questions about how to pare that down or cull or have a plan that works. 

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You think I should do that? I wasn't wanting to work on the transmission or anything just trying to change my automatic to a manual so I was trying to figure out which manual transmission would bolt up to that engine. Cuz I'm just going to put it in from the bottom as an assembly. And this project is mainly for me to teach myself for future that's why I'm doing it on an older Subaru and just trying to learn as much as I can from experienced Subaru mechanics before I jump into it. If you think turboing the naturally aspirated engine would be to big do you have a suggestion for it already turboed engine? Or should I go on like foreign engines or JDM and get a turbo 2.5?

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Your best bet is to buy a Subaru that’s closer to what you want (Manual or bigger engine or turbo or whatever you want). What do you want? Go buy that.

Then learn by learning how to maintain brakes, do preventative maintenance, do upgrades, and ask specific questions about which turbo or how to rebuild a turbo or upgrade Intercooler, etc.

If you absolutely insist on jumping into a big project then buy one that needs work - buy a blown turbo with manual trans and repair it or one with a wrecked bumper and swap bumpers…

I think that’s about all I can help on this conversation, so I’llbe checking out. Good luck and enjoy the soob. OBS are great, reliable transportation. They’re about the easiest and inexpensive 200,000 miles you can get.

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If you’re going to turbo an NA block get on rs25 forums and have a read. Many on there and NASIOC forums. Also check out YouTube for the many build videos on there. Be warned they drag out though to get the video run for their channel… 

There’s a lot to do and get right so you don’t melt a piston or throw a rod in an NA-t build, but it can be done. 

Any EJ gearbox will bolt up to the EJ engine. Their bolt patterns are 4 bolt or 8 bolt and are interchangeable anyway. 

Cheers 

Bennie

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