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Hi guys,

So my buddy has had a 02 WRX with a turbo EJ25 rotting in his yard for 6 years. I offered to buy it and he’s basically giving it away. It turns out it’s got an EJ257 in it right now with forged internals and the 2.0 heads. The current EJ257 block has a crack in it so i’ve been looking for a new engine.

My original plan was just to buy a full EJ25 engine and then swap my heads onto that engine and drop the motor in along with a new ECU and injectors (current ECU is tuned for e85). I know nothing about Subarus so does this sound like the best idea? I saw an entire EJ25 engine with accessories that came out of a subaru legacy on ebay for a good price and I was thinking about going that route.

My other option was to just buy an ej25 short block and swap the forged internals from my cracked block to the new short block. This would be more work I understand but maybe this is a better idea?

Thanks again for the help,
Justin
 

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Usually forged parts are ordered sized per block. I'd order a staged block from iag. Get it rebuilt and take it to a tuner to have them look it over and tune it.
 

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Usually forged parts are ordered sized per block. I'd order a staged block from iag. Get it rebuilt and take it to a tuner to have them look it over and tune it.
See I understand that this would be the “right way” to do the project. I’m just worried about the condition of the car after sitting for so long in his yard. This is the reason why i’m trying to get it back on the road for as cheap as possible so that I can confirm the car is even worth saving before I drop 4k on a built short block from IAG.

Because of this, that’s why i’m trying to pursue other options before I have to do a full build. Honestly, whatever motor I drop in here I could care less if it blows in the first couple months. I just want to know if this car is still worth saving if that makes sense.

Thank you very much for your reply.
 

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My original plan was just to buy a full EJ25 engine and then swap my heads onto that engine and drop the motor in along with a new ECU and injectors (current ECU is tuned for e85). I know nothing about Subarus so does this sound like the best idea? I saw an entire EJ25 engine with accessories that came out of a subaru legacy on ebay for a good price and I was thinking about going that route.
You could do this, but swapping heads is no small task. Alternatively, there have been some who have installed an EJ257 longblock in a bugeye chassis while retaining the 16bit ECU (this does require the original manifold be used).

That option will require you to delete the AVCS (this involves plugging oil passages in cam gear) and some loom splicing. The benefit is that you will get a fully assembled OEM short block (more reliable in general) and better heads/cams than what are on there right now.

Either way, you will put in some effort to make this happen. The easiest and cheapest approach would be to find a junkyard EJ205 and drop it in there.
 

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Either way, you will put in some effort to make this happen. The easiest and cheapest approach would be to find a junkyard EJ205 and drop it in there.
Yeah I really don’t want to go down to the 2.0L just because of the power. I feel like I would rather have the 2.5 even if the motor does blow it would be a chance i’d be willing to take.

You could do this, but swapping heads is no small task. Alternatively, there have been some who have installed an EJ257 longblock in a bugeye chassis while retaining the 16bit ECU (this does require the original manifold be used).
I’m pretty sure this is what my buddy did before but don’t take my word for it. I can’t find the engine code to be 100% sure of the engine. All I know is that the engine has dual cams, JDM 2.0 heads and “supposedly” forged internals.

Is there any reason why swapping heads is no small task?

Also, yes I was reading about the AVCS and I wasn’t sure how much of an advantage it would be to enable/disable this feature. I would love to hear your input.

Thank you guys so much.
 

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See I understand that this would be the “right way” to do the project.
Then why is there any question? This isn't a half ass your way through life project. You can detonate an engine in minutes if you fudge your way through this.
Yeah I really don’t want to go down to the 2.0L just because of the power. I feel like I would rather have the 2.5 even if the motor does blow it would be a chance i’d be willing to take.
There isn't all that much power difference. Not enough you would even notice.

I wouldn't chance 3-5k to save 5 bucks. Thats just bad math. Do it right the first time, or this isn't a project you want to take on. These "junkyard find/build/blahblah" youtube channels have placed an unrealistic image in peoples minds of how this kind of thing works. You don't just hodgepodge a bunch of bs together and have a reasonably functioning car.
 

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Is there any reason why swapping heads is no small task?
I've never done it, but keep in mind there are two heads on a flat-4 which means twice the work. Aside from the prep to remove the heads (valvetrain has to be disassembled IIRC), you will need to invest in new supporting hardware i.e. head bolts and head gaskets which adds to the cost. If those are 2.0L heads as you mentioned, the combustion chamber should have been machined to match the 2.5L bore. If not, that will add more cost and time for you (do not cheap out on this one). On top of everything, an unopened block tends to be more reliable so you've got that going for you as well.
 

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Discussion Starter #8
've never done it, but keep in mind there are two heads on a flat-4 which means twice the work. Aside from the prep to remove the heads (valvetrain has to be disassembled IIRC), you will need to invest in new supporting hardware i.e. head bolts and head gaskets which adds to the cost. If those are 2.0L heads as you mentioned, the combustion chamber should have been machined to match the 2.5L bore. If not, that will add more cost and time for you (do not cheap out on this one). On top of everything, an unopened block tends to be more reliable so you've got that going for you as well.
Ok cool thanks and yeah they have been machined to match the 2.5 bore.
 

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There isn't all that much power difference. Not enough you would even notice.

I wouldn't chance 3-5k to save 5 bucks. Thats just bad math. Do it right the first time, or this isn't a project you want to take on. These "junkyard find/build/blahblah" youtube channels have placed an unrealistic image in peoples minds of how this kind of thing works. You don't just hodgepodge a bunch of bs together and have a reasonably functioning car.
Got it, thanks so much for your input I really appreciate it. I didn’t know the performance was so similar between ej20 and ej25.

And honestly it’s not just a few bucks the legacy motor is only $900 and the IAG closed deck is right at 4k.

Thanks so much for your help.
 

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Got it, thanks so much for your input I really appreciate it. I didn’t know the performance was so similar between ej20 and ej25.

And honestly it’s not just a few bucks the legacy motor is only $900 and the IAG closed deck is right at 4k.

Thanks so much for your help.
You are leaving out the block machining that will need to be done, the heads will need cleaned and machined, you'll need to have the cylinders bored/honed to fit the forged internals you wanted to swap over. The list goes on and on. This is a very expensive project that can FAR exceed any value that car has. If the body is in good shape, transmission is solid, and there are no other huge red flags find a USDM ej205 pull that has been inspected where they can provide leakdown and compression test results and have a performance shop drop it in and retune it for the time being. Then start saving for your project.
 

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Discussion Starter #11
You are leaving out the block machining that will need to be done, the heads will need cleaned and machined, you'll need to have the cylinders bored/honed to fit the forged internals you wanted to swap over. The list goes on and on. This is a very expensive project that can FAR exceed any value that car has. If the body is in good shape, transmission is solid, and there are no other huge red flags find a USDM ej205 pull that has been inspected where they can provide leakdown and compression test results and have a performance shop drop it in and retune it for the time being. Then start saving for your project.
I see what you’re saying now all of that work does add up. The transmission is built too he’s got the paperwork for it. I’ll check on pricing for an EJ205.

Is there any reason to go AVCS/non-AVCS? I see some motors have it and some do not have it.
 

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Vairable valve timing can improve the overall power curve lifting it across nearly the entire rpm band
 

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Vairable valve timing can improve the overall power curve lifting it across nearly the entire rpm band
Thanks, ok so i’ve decided on the ej205 for now. I also need an ecu for it. Is there anything in particular I need to watch out for when purchasing a compatible ecu? Or any in general tips you might have for the engine install? I’m trying to reuse the turbo that is on my current engine with the ej205 replacement as well but just plan to keep the boost low.
 

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I’m trying to reuse the turbo that is on my current engine with the ej205 replacement as well but just plan to keep the boost low.
Not a good plan. You should replace with OEM turbo OR remap with the new engine.
 

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Not a good plan. You should replace with OEM turbo OR remap with the new engine.
Awesome thanks for this info. I can get remap via an ecu tune right? I’ve heard a lot of good things about Shinji Tuned.
 

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Yes.
 

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find a USDM ej205 pull that has been inspected where they can provide leakdown and compression test results and have a performance shop drop it in and retune it for the time being. Then start saving for your project.
I found these ej205 online which one do you guys recommend? I was afraid the first link might be v5/6 so it would be a lot of trouble with my usdm harness and loom.
JDM EJ205
EJ205 AVCS
 

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Neither. USDM is what you want. Focus there.
 

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Neither. USDM is what you want. Focus there.
Any particular reason why the JDM AVCS one will not work? It says it is 100% plug and play (without avcs)... and it’s a version 7 engine. If I wanted to use the AVCS they sell the harness/ecu as a pair for $150
 
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