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I just bought this car yesterday and im planning on doing this swap pretty soon. I choose this over the 2.2t becuase if I did the 2.2t I would leave it mostly stock and make about the same power as the 2.5 but would have to run 93 octane. I also thought about doing a 2.5 block with 2.2 heads and the thin HG, but again that would requite 93 octane. Anyway, anyone running a 2.5? Also, this is going to be hooked up through a fwd 5 speed.

not everyone at once...

have you tried the search button...

My plans are similiar. I plan on 2.5 heads on my 2.2t block. Our blocks are legendary for being very tough there are guys and gals out there running 25 + psi with this setup.

skid542 wrote:have you tried the search button...

as a matter of fact I have, thanks

irishsetter wrote:My plans are similiar. I plan on 2.5 heads on my 2.2t block. Our blocks are legendary for being very tough there are guys and gals out there running 25 + psi with this setup.

that will make for a badass motor. Low compression ratio, bullet proof block, great flowing heads, you cant ask for anything better. If I were going turbo that would be how I would do it for sure. BUt at this point I just want something good for daily driving, good on gas, and still some good power to it. I think the 2.5 will do that for me. Now if I can only get a hold of one for a decent price...

tzedek wrote:

skid542 wrote:have you tried the search button...

as a matter of fact I have, thanks

Good, you'll become good friends with it if you stay around here for a while. There's a wealth of knowledge in the archives.

There are several guys around here running the 2.5, phase I and II, as well as a few guys running 'frankenstien' engines using 2.5 components. There is even a few with a EJ257 transplants. All of them have had good sucess but if you plan on putting that much power through a FWD tranny, start your budget for a tranny. You should also upgrade your tires if you're still running the 14's that came standard on the FWD's. You'll still expel most of the excess power by spinning your tires in 1st on a launch but if you are shifting hard, you'll break 2nd. Also, wheel spin with become a serious problem for you. With just my NA I still break the tires loose shifting into 2nd if it's a little wet or I'm shifting in a turn. If you are going to plunk the money down for a 2.5, I'd just go ahead and do the AWD conversion. Just my .02.

I'd love to do with the AWD swap at the same time, but thats a lot more time/work/money etc. Are the FWD trannys known to be weaker? I plan on getting some WRX wheels/tires for my car before we do the swap. Those should help me hook up a bit, but I realize I will still be fighting wheel spin. But then again I dont plan on living my life a 1/4 mile at a time if you know what I mean. anyway thanks for the help

Think of the tranny this way, it was designed for a 130hp engine, how much are you throwing at it? How many miles is already on your transmission at that? I'm not saying you'll break the tranny right at first but after a little while I'd think it's going to take it's toll. Someone with more knowledge of our transmissions can/will correct me if I'm wrong.

As far as wheel spin, you don't have to live your life 1/4 mi. at a time to have a problem. If it's raining out, I constantly have to be aware of wheel spin. Granted my front end is lighter than stock and you'll be a little heavier so maybe you won't have as much trouble as I do. It's not unmanagable of course but sometimes it's a real bitch. Come time for snow though.... Spending money on good tires will help too. I'm not running racing tires but they aren't RE92's either. You should also check the drivetrain forum on whether or not your clutch will work, if you haven't already. I can't recall off hand what/if you'll need to do but I do seriously doubt that the stock clutch will hold the power for too long.

Ill be using a Forrester clutch with the 2.5, so long as it works with our tranny. the 2.5 is rated at 165/162 so its not a huge increase really. My tranny has 155k miles on it. To be honest with you im not really worried about, and thats not just me being cocky and thinking I know all this and that. If it does let go on me then ill either be finding a new one or doing a AWD swap at that time. See the thing is there is actually a really good Subaru crew here in my local town. The only reason I ever got into it was becuase my best friend is into Subarus. He works at the local dealership. 1 guy that I know has a 92 leg sedan FWD with 25 dohc and 4.44s and some other stuff like borla header, borla cat back. My best friend has a 98 Impreza 2.5 block 2.2 dual port legacy heads borla header custom done exhuast with no cats, perrin pulley, intake, coil overs and tons of other stuff. Anyway without getting into my life story im not too worried about it.

Yeah it sounds like you should be in good shape. Like I said, I don't think the tranny will die right away but after time I'd think a 25% increase in power would take it's toll. But it would make a good reason to go AWD as you mentioned. There was some talk about the forester clutches/flywheels not too long ago I think, again though I don't recall the full story. Keep us posted.

I dunno why you would wanna use a Phase I EJ25. That engine is the worst headgasket-blower in Subaru's history. 96 Outbacks seem to be the worst; some people have replaced them 3 times on the same car.

If you want to make a hybrid N/A motor with big power, put EJ22 heads on an EJ25. Your compression ratio will then be high enough that you would have to use premium gas, and I'm sure you would be making 170-180hp at the least.

subyluvr2212 wrote:I dunno why you would wanna use a Phase I EJ25. That engine is the worst headgasket-blower in Subaru's history. 96 Outbacks seem to be the worst; some people have replaced them 3 times on the same car.

If you want to make a hybrid N/A motor with big power, put EJ22 heads on an EJ25. Your compression ratio will then be high enough that you would have to use premium gas, and I'm sure you would be making 170-180hp at the least.

I take it you didnt read my first post.

I did read your first post, and according to what you said, swapping heads was one of your ideas, not your definite plan. So logic suggests that you were also considering using a EJ25 Phase I longblock.

actually, I thought about doing a hybrid swap but decided not to becuase of premium gas and possibly reliability as well as other issues. Anyway I am going to stay away from MY96, but it looks like I will be able to get a decent deal on a motor from a RS. Most likely will be a SOHC, but thats ok anyway. There are a bunch of people over on NASIOC that have done STi swaps and have good motors left over for cheap. As well as front brakes, exhuast, etc.

after a little more researched I have found that subyluvr was right about the phase I motors, and the problems with them are even more extensive than he stated. So for anyone else interested you want to get a motor from 99+ Impreza/Forester or 00+ Leggy. As I said before great deals can be found from guys swapping STi stuff into their RS imprezas, just stay away from the 98RS of course. The downside is that the SOHC motor is a bit more work to swap in.

if you use the phase I EJ25 block with phase II EJ22 heads and the new 4 layer headgasket you should be fine, and it will put you at around 10.8:1 CR, so you can run medium grade gas instead of premium, thats my plan at least. a factor that alot of people forget about is the fact that aluminum heads dont get re-tightened after they leave the factory, if you re-torque them after a couple of heat cycles, i dont think your HG problem will be that much of a problem. i mean come on now, if you have to do a headgasket job every 50k, 3 years, big deal. i personally dont give a crap, it seems to me after 50k miles, shouldnt you do something to your motor to keep it running like almost-new?





~Josh~

do yourself a favor and stay away from the Phase I blocks.

tzedek wrote:do yourself a favor and stay away from the Phase I blocks.

What a load of hooey! Do you realize that every guy on this board with a stock engine is running a phase I block? Phase I blocks are not somehow inherently weak, even in the Ej25 version. Yes, phase II Ej25 blocks are stronger, but there is a recall and warranty coverage on the SOHC Ej25's as well because they blew head gaskets just like the DOHC's did. Mine blew, as did many others.

I think you need to follow the old saying," god gave you two ears and one mouth, so you should be doing twice as much listening as talking!" You have flipped around in a circle on your opinions in this thread just based on getting more information. Embrace finding the right answer versus being right!

So, a couple of things to add. You state putting a DOHC EJ25 in versus a SOHC Ej25 is easier. Just not true. The SOHC Ej25 is a very simple swap. You also make it sound like you are making some compromise by getting SOHC versus DOHC heads. These aren't Hondas. There is no truth there. You have one cam per bank of 2 cylinders. As such, each camshaft has half as many lobes on it as a SOHC cam in an inline engine. This makes for savings of valvetrain intertia over a traditional SOHC design as well as over the DOHC Subaru heads that have two sticks per bank of cylinders.

Furthermore, the roller rocker valve actuation of the SOHC Ej25 heads is superior to the DOHC ones. They open and close more quickly, and show virtually no wear. Getting a SOHC EJ25 is in no way a compromise.

Also, as has been mentioned, the CR bump with an Ej25 bottom end w/Ej22 heads is not so extreme as to warrant premium gas. 89 octane, yes, but not 91 or above. I have built a couple of these Ej25/Ej22 hybrids that our members are running, and they were all on phase I blocks. Part of the idea that the phase I blocks were weak came from Mike Shields old article about why he wouldn't build a turbo kit for them. If you are not throwing a ton of boost at them, they are good reliable blocks. I don't know of a single person with a phase I Ej25 who had their bottom end go out in less than 100k mi. While this is not the 200-250k mi many of our Ej22E powered friends have seen, it is not a really low mileage. And many of them have gone the 150-200k mi distance as well...

I think that's all for now...

Matt Monson wrote:

tzedek wrote:do yourself a favor and stay away from the Phase I blocks.

What a load of hooey! Do you realize that every guy on this board with a stock engine is running a phase I block? Phase I blocks are not somehow inherently weak, even in the Ej25 version. Yes, phase II Ej25 blocks are stronger, but there is a recall and warranty coverage on the SOHC Ej25's as well because they blew head gaskets just like the DOHC's did. Mine blew, as did many others.

I think you need to follow the old saying," god gave you two ears and one mouth, so you should be doing twice as much listening as talking!" You have flipped around in a circle on your opinions in this thread just based on getting more information. Embrace finding the right answer versus being right!

So, a couple of things to add. You state putting a DOHC EJ25 in versus a SOHC Ej25 is easier. Just not true. The SOHC Ej25 is a very simple swap. You also make it sound like you are making some compromise by getting SOHC versus DOHC heads. These aren't Hondas. There is no truth there. You have one cam per bank of 2 cylinders. As such, each camshaft has half as many lobes on it as a SOHC cam in an inline engine. This makes for savings of valvetrain intertia over a traditional SOHC design as well as over the DOHC Subaru heads that have two sticks per bank of cylinders.

Furthermore, the roller rocker valve actuation of the SOHC Ej25 heads is superior to the DOHC ones. They open and close more quickly, and show virtually no wear. Getting a SOHC EJ25 is in no way a compromise.

Also, as has been mentioned, the CR bump with an Ej25 bottom end w/Ej22 heads is not so extreme as to warrant premium gas. 89 octane, yes, but not 91 or above. I have built a couple of these Ej25/Ej22 hybrids that our members are running, and they were all on phase I blocks. Part of the idea that the phase I blocks were weak came from Mike Shields old article about why he wouldn't build a turbo kit for them. If you are not throwing a ton of boost at them, they are good reliable blocks. I don't know of a single person with a phase I Ej25 who had their bottom end go out in less than 100k mi. While this is not the 200-250k mi many of our Ej22E powered friends have seen, it is not a really low mileage. And many of them have gone the 150-200k mi distance as well...

I think that's all for now...

I read an article outlining the differences in the Phase I and II blocks and I would not use a p2 block. I cant seem to dig it up, but the phase I blocks are prone to piston slap. I didnt mean to say that the DOHC head is any better than the SOHC head or vise versa, that was an accident. The SOHC swap requires more wiring as well as making a shim for the tb, I would call that more difficult than a drop in swap, maybe not to you as for you thinking I could run mid grade gas on a 2.5/2.2 hybrid, a friend of mine runs a phase 1 2.5 block on phase 2.2 dual port heads with the thin HG and he has to fight deto on 93 octae. I think im all set on that, and listening to people over the internet rather than someone who has done it and has seen real results. and besides it should be easier to find an entire motor and do the swap, rather than source a block, source heads and go from there. thanks

The reason you friend is having detonation issues is because he used the wrong head gasket. You want to use the phase I .060" HG with that swap. That's how you get a CR in the mid tens. He's probably running in the neighborhood of 12+:1 CR. His engine is a time bomb.

As for listening to people on the internet versus real life? You obviously haven't been around much. I have built 3 Ej25/Ej22 hybrids, as well as coached a number of our members through their own builds and installation, with none of the detonation problems your friend suffers. I won't go into how I have been playing with these engines forever. Just go look me up on NASIOC and you might figure out that I know what I am talking about...

I need to clarify my original post I think.

When I read the title of "2.5 DOHC Phase I swap" I figured you were going to swap that engine in your car without touching it. As it is, the early DOHC EJ25's are headgasket-blowers, however that doesn't make their bottom ends weak.

If you're going to be experimenting with head-swapping between different blocks and stuff, our friend Matt here is the man to talk to. I don't know of anyone who has more experience building Subaru engines than he does.