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Thread: Summary of the Phase 1 USDM EJ Series.

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    Default Summary of the Phase 1 USDM EJ Series.

    When it comes to EJ22s, there are 3 Phase 1 variations here in the USA.
    They are also all SOHC as the USA did not get a DOHC version. Ever.
    All have the same bore, stroke, & forged internals (rods, crank) with slight differences.

    1992-1995 EJ18E:
    These engines have open decks, SOHC, & dual exhaust ports per head.
    They are generally reliable & problem free when taken care of.
    ONLY found in Imprezas in the USA.
    No other model used this engine.
    Compression ratio is about 9.6:1
    This engine produces about 110bhp.

    1990-1995 EJ22E:
    These engines have open decks, SOHC, & dual exhaust ports per head.
    Pretty problem free for the most part of they're taken care of.
    They share rods w/Phase 1 EJ20s & EJ18s & generally produce about 130-135bhp.
    Compression ratio is about 9.5:1 max.

    1996-1998 EJ22E:
    The 2.2 engine was further upgraded with higher compression, molybdenum coated pistons.
    They also received valvetrain changes in the cylinder heads to reduce friction & single exhaust ports per head.
    The block is open deck, the same as the first EJ22E.
    The piston crowns in these engines are different than those in the earlier variations.
    The compression ratio in this variation is about 9.7:1 max.
    It produced 135bhp but there were a few dual ports produced in 1996 as Subaru was overstocked w/EJ22s @ the time of mass production.

    1991-1994 EJ22T:
    The only turbocharged variant of USDM Phase 1 EJ22s.
    These have closed decks, piston oil squirters, deeper dish pistons, slightly thicker rods, & their heads are drilled/tapped for turbo.
    The camshaft has a profile that's set up for turbocharging & the valves are smaller than that of the 22E variant.
    These are very strong but like all other things, can & will be destroyed if they are put under too much stress.

    Now onto the EJ25D.
    We got 3 variations of these in the USA (the last variation actually being a cross between Phase 1/Phase 2) & they produce 155-165bhp.
    They have larger bores & higher strokes than the EJ22 along with thinner piston rods that are NOT forged & not nearly as strong.
    As such, they naturally produce more power & tq but are not nearly as reliable due to their habit of blowing head gaskets like its their job.
    The cylinder heads are variations of JDM heads but have lower RPM limits & lesser valvetrains.

    1996 EJ25D:
    These came equipped in 1996 Outbacks, GTs & LS/LSi & were bolted to an automatic only.
    They could not be had any other way.
    The 25D of this year had 9.5:1 compression, domed head chambers which were cut to the bore of the block, & high compression pistons.
    These did blow head gaskets but not nearly as much as their later variations.
    The cylinder heads had hydraulic lifters & larger intake ports than its later variations.
    This engine made peak tq @ 2800rpm, which I personally think is awesome.
    The peak bhp was 155 max.

    1997-1998 EJ25D:
    This engine recieved changes to its valvetrain, Subaru got rid of the hydraulic setup to produce more power at higher rpms but lost the ability to produce peak tq @ low rpms.
    The chambers are cut into clover shapes & are not domed as the earlier variant was.
    The intake ports are larger than that of the 96 DOHC heads.
    The pistons are also deep dish & square cut.
    Rods & crank are the same as the 96 variant.
    These were prone to head gasket leaks, which would lead to compromised & destroyed internals.
    These were now in autos or manual transmission equipped cars.
    Peak bhp is 165 max.

    1999 EJ25D:
    The factory "hybrid."
    It has Phase 1 1997-1999 heads on a Phase 2 block with 1996-1999 internals (pistons) but the crank is Phase 2.
    Came in auto or manual transmission equipped cars.
    This engine produced the same power as the variant before.
    Peak bhp is 165.

    All EJ22s have 52mm rod journals & all EJ25Ds have 48mm rod journals.
    This is the gist of what you're working with when you're dealing w/Phase 1 USDM EJ engines.

    This is all of the general info that I have been able to gather from personal experience as well as others who have worked w/Phase 1 Subaru EJs. Don't let the horizontally opposed architecture of the engine surprise you. It's actually a really simple concept. Just another 4 stroke engine with an extra cylinder head. That is all it is.
    Last edited by EJ22D; 02-28-2013 at 10:07 PM.

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    I've noticed that there are many questions regarding hybrid engines & while I'm not going to go into full detail, I am going to explain the hybrids that I know will work with the stock Phase 1 ECUs that we have here in the United States. If anyone has more info on their hybrid builds, please feel free to chime in. Also, the use of different sized head gaskets will determine the end ratio. I'm just explaining the different types of hybrids on stock head gaskets & head gaskets MUST AT ALL TIMES match the bore of the block. If you have an EJ22 block, the EJ22 head gasket must be used & so on.

    Dual Overhead Cam EJ22:
    Done by installing EJ25D heads on an EJ22 (E or T).
    There is no need to change sensors on the heads of the block since they are the same.
    This hybrid has lowered compression (Es have 9:1 while Ts have 7.5:1) from it's original SOHC variant & is better for turbocharging, since it has pretty deep chambers combined with dished pistons.
    The DOHC 22Es can be used as they produce a little more midrange power than the SOHC 22Es but the 22Ts should not EVER be used without turbocharging.
    The best DOHC heads to use are the 97-99 heads as the chamber is enclosed in the bore of the EJ22's cylinders while the 96 25D chambers are cut to the bore of the 25D & should not be used on any EJ22 block.
    This engine can be safely run on 87 octane.
    Any Phase 1 ECU will run DOHC heads, even the first generation Legacies.

    "Big Valve" EJ22T:
    This is done by bolting EJ22E heads on an EJ22T block.
    The compression ratio doesn't change much but the 22E heads have bigger valves, so this helps out w/tq delivery as a little more air is brought in to be compressed.
    The heads are essentially the same as the turbo heads but they have to be drilled & tapped for turbocharging.
    You must also use the 22T camshafts in this build as they have profiles for the turbocharger.
    The 22T computer will run these heads without an issue.

    Single Overhead Cam EJ25D:
    This is any 25D block w/EJ22 heads on it (the EJ22 heads have small chambers, which contributes to the high compression).
    Again, no need to change sensors.
    However, the compression ratio increases tremendously (approaching 11:1), which necessitates 91+ octane be used at all times to keep detonation at a minimum to zero.
    There are reports of this hybrid produces 180+bhp & nice tow-end tq.
    This would probably be an engine good for rock climbing, mudding, rallying, & "dirty" situations.
    The 97-99 25D block provides a lower compression than the 96 block, which has flat top pistons designed for max compression.
    Using a 96 25D block may cause some issues with compression being TOO high & require more depth of control, like installing a stand alone ECU.

    High Compression DOHC EJ25D:
    This is made by installing 97-99 25D heads on a 96 25D block.
    Compression is about the same as the SOHC 25D variant & it must be run on 91+ octane also.
    The powerband is pretty much an exaggerated version of the 97-99 EJ25D.
    This hybrid can run on the stock ECU.

    Low Compression DOHC EJ25D:
    This is made by installing 96 25D heads on a 97-99 25D block.
    Compression is lowered to about 8.8:1/9:1 & makes this engine good for turbocharging but on the flipside, the heads do not allow very high revs.
    Power produced is more or less that of a 96 25D.
    This engine can run safely on 87 octane & on the stock ECU.

    I only have pictures of my DOHC EJ22E hybrid but I have seen the hybrids I have mentioned (haven't seen a 96 25D SOHC yet) & they all seem to work well but the SOHC 25Ds grant the most power & low-end tq out of all the builds & are easier to maintain, since they have the simplicity of the SOHC design.

    Hope this helps anyone who wants to have general info on EJ hybrids.

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    Alot of great info there, thanks for posting it up!

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    What about the phase 2 EJ22? From 99-01.
    AdidaSubarus

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    Quote Originally Posted by bratman18 View Post
    What about the phase 2 EJ22? From 99-01.
    Phase 2 EJ22s (EJ222) are much more like EJ251s & EJ253s & should be treated as such.
    Externally, they look no different from the SOHC Phase 2 EJ25s.
    They are open deck & extremely tough engines, just like their Phase 1 predecessors.
    What's even better about them is that the blocks are pretty much overbored EJ205 w/higher compression pistons that even have valve reliefs for the fitment of DOHC heads, as if that engine was supposed to be DOHC but at the last minute, someone at the R&D department changed their mind.

    If a builder wanted to (and I really recommend this), they could use the 222 block in place of the 205 block to gain %20 more displacement for any WRX.
    The rods & crank are the same as those used in the 205 & even have the same strength.
    I used this block for the building of my first DOHC EJ22 & it really had a bit of pickup for what it was.
    Hell, we can talk EJ22 all day (I don't think I'd ever choose an EJ25 for anything unless it was a 255/257) but I'm just going to say that whatever EJ22 you get a hold of will be an excellent base to start modding from.

    If you're thinking of using an EJ222 in a 90's car (Phase 1), you will need to get rid of your heads, sensors, & crank gear/sprocket & switch over to those from the Phase 1.
    For example, a DOHC EJ222 would consist of the following:
    97-99 EJ25D heads/cam gears.
    EJ222 block.
    EJ25D wiring & sensors.
    EJ25D or EJ22E crank gear/sprocket.

    If you wanted to make a high compression EJ251/3 (11.5:1), you would take the EJ222 heads, bolt those onto your 251/3 block, & swap the 251/3 cam gears over.
    Your could also swap cams between the heads & see what kind of performance you come up with since the cams have different profiles.

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    ^That's the kind of response I was looking for. Great write up and info. There are a lot of people that don't know this stuff!
    AdidaSubarus

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    Quote Originally Posted by bratman18 View Post
    ^That's the kind of response I was looking for. Great write up and info. There are a lot of people that don't know this stuff!
    Thanks!

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    Another thing I'd like to mention.
    The EJ18E shares it's internals w/EJ20E, EJ20D, & EJ22E, & they have the same strength as those found in the 22T, so there is no need to swap internals. There are people out there boosting them the way that they are because they are apparently very strong little engines.

    The heads of the 18E are very similar to those of the 22T/E to the point where you cannot tell the difference between them externally. Internally, the 18E heads would be suitable for boost if they were drilled & tapped & had 22T cams in them. Other than that, there is no need to change heads, IF your head gasket is thick enough.
    I believe that the 18E heads have a lower cc than that of the 22E/T heads. I'll have to double check on that.

    The REAL question is whether or not one can put DOHC heads on an 18E block, like 25D heads or 20K heads, for example. That would be a great upgrade for 18E blocks, if it were possible.

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    If you're into building EJ22D's, you need to read this closely, because it matters to you, and only 97-99 EJ25D heads will be used in this equation, as the 1996 EJ25D heads have chambers which are too large for the EJ22 bore, and should never be used in this sort of application.

    EJ22D Version 1 - EJ25D heads + EJ22E/1 block (14.5cc pistons) = EJ22D V1: N/A w/ EJ222 headgaskets yields 9.3:1cr, but EJ22T head gasket yields 8:5.1.

    EJ22D Version 2 - EJ25D heads + EJ22E/2 block (12cc pistons) = EJ22D V2: N/A w/EJ222 head gaskets yields 9.6:1cr, but EJ22T head gasket yields 8.8:1.

    EJ22D Version 3 - EJ25D heads + EJ221/2/3 block (3.5cc pistons) = EJ22D V3: N/A w/EJ222 head gasket yields 10.3:1cr, but EJ22T head gasket yields 9.8:1.

    EJ22D Version 4 - EJ25D heads + EJ22T block (28cc pistons) = EJ22D V4: EJ222 head gasket yields 7.8:1cr, but EJ22T head gasket yields 7.4:1cr.

    There are only FOUR EJ22D variants that can be achieved with 97-99 EJ25D heads and all of the EJ22 blocks in combination form. All 97-99 heads have a 46.6cc (rounded up to 47) clover chamber, and all EJ22's have a 97mm bore, 75mm stroke. I repeat, do NOT use 1996 EJ25D heads. Those are identified as having "16 Valve Quad Cam" on their valve covers.

    A long while back, when I first started building these, I originally based my coding off of what Subaru does to its EJ's to keep the identification easy. Example, if you're using EJ20K heads on an EJ22E block, I would call that combo the EJ22K, since the 5th digit identifies the heads in use. Have fun with this knowledge.

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