General Hybrid Info on EJ25D - EJ22E/T

[EJ22D]

EJ22E:
We got 3 variations of these in the 2nd generation Subaru Legacy.
1995-1996, 1997-1998, & 1999 are the years in which the 3 variations were released.
This engine (1995-1998) is pretty much a rinse & repeat from the first #3 main thrust bearing EJ22E produced in 1990-1994.

1990-1995 EJ22E:
These engines are pretty much the same as the 1990-1994 EJ22E enginess except with VERY SLIGHT changes to the sensors & wiring.
These engines have open decks, SOHC, & dual exhaust ports per head.
Pretty problem free for the most part if 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.

1999 EJ221/2/3:
This engine is fundamentally different from the previous variations in that it has flat topped pistons, entirely different cylinder heads, & is a complete Phase 2 engine with the main thrust bearing on position #5.
It produces 145bhp & has the same crank & rods that the EJ205 has.
The cylinder heads & intake are almost the same as those used in the Phase 2 EJ25 SOHC engine but with a few differences, mainly in bore, stroke, & camshaft areas.
The electronics used in this engine are also fundamentally different than the previous EJ22s & it cannot be run on Phase 1 electronics.

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.
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 & hydraulic valvetrains.
The heads on this engine bring in more air than those of the EJ22 so if you have an EJ22 & you put these heads on, you will have a very efficient & capable engine with lots of potential for turbocharging.
Although you'll lower compression to an EJ22 by using these heads, you can make up for the difference, usually by turbocharging that combo.

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, but smaller exhaust 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 received 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 pistons are also deep dish & square cut.
Rods & crank are the same as the 96 variant.
These were prone to internal head gasket leaks, which would lead to compromised & destroyed internals.
Peak bhp is 165 max.

1999 EJ25D:
The factory Subaru "hybrid."
It has Phase 1 1997-1999 heads on a Phase 2 block with 1996-1999 internals (pistons) but the block & internals are of the "Phase 2" type.
This engine produced the same power as the variant before.
Suffered internal head gasket leaks & problems the same as the variation before.
This engine used the Phase 1 electronics until the big switch over to the 3rd generation Subaru Legacy.
Peak bhp is 165 max.

All EJ22s have 52mm rod journals & all EJ25Ds have 48mm rod journals except for the 1999 EJ25D, which has 52mm rod journals.
This is the gist of what you're working with when you're dealing w/Phase 1 2nd Generation Subaru Legacy USDM EJ engines.

(This post should stick around for as long as possible so people who come here know what engines they have & what they're dealing with.)

*Revised*.

[Reason]

This is good info and we can use this to build on. I have a EJ25D from a 97 Legacy and phase one EJ22E heads w/hybrid cometic gaskets.

[EJ22D]

This is good info and we can use this to build on. I have a EJ25D from a 97 Legacy and phase one EJ22E heads w/hybrid cometic gaskets.

The 97-99 blocks are probably better for the SOHC 25D builds since the compression ratio is at a more tolerable level. I have a dual cam 22E that's been running for 4Kmi so far without serious issues. I have Victor Reinz gaskets for a Phase 2 EJ22 & they have held up well. Do you have cams & head work done or is it all stock & put together?

[couchfuzzy]

Id like some more info on the 25 heads on the 22t specifically, I've read that the whole obd1 to obd2 is going to need a standalone em, but what us the deal with the wiring harness? And what kind of gains are to be had?

[Reason]

This is good info and we can use this to build on. I have a EJ25D from a 97 Legacy and phase one EJ22E heads w/hybrid cometic gaskets.

The 97-99 blocks are probably better for the SOHC 25D builds since the compression ratio is at a more tolerable level. I have a dual cam 22E that's been running for 4Kmi so far without serious issues. I have Victor Reinz gaskets for a Phase 2 EJ22 & they have held up well. Do you have cams & head work done or is it all stock & put together?

I have Delta Cams torque grind, and I smoothed out the ports slightly, nothing crazy like a port job.

[Garrison]

Id like some more info on the 25 heads on the 22t specifically, I've read that the whole obd1 to obd2 is going to need a standalone em, but what us the deal with the wiring harness? And what kind of gains are to be had?


Here you go dude:
viewtopic.php?f=59&t=23704 (https://sl-i.net/FORUM/viewtopic.php?f=59&t=23704)

viewtopic.php?f=31&t=25426 (https://sl-i.net/FORUM/viewtopic.php?f=31&t=25426)


The only reason to run standalone on OBD2 is... nothing that I can think of. Unless you're just throwing in some crazy engine swap or something. Piggybacks will suit you fine, and let you decrease timing/add fuel which is really the only things you need be concerned with.

[chuckthefuk]

EJ22D !!!! You are amazing!

Once you are done compiling and fortifying info I would like to format the page and create a sticky. I would also like to compile a turbo ej hybrid thread. Maybe you will have some time in the next few weeks/months to help me out.

-Chuck

[EJ22D]

EJ22D !!!! You are amazing!

Once you are done compiling and fortifying info I would like to format the page and create a sticky. I would also like to compile a turbo ej hybrid thread. Maybe you will have some time in the next few weeks/months to help me out.

-Chuck

Thanks! There is more info than what I have in my notes about the EJ hybrids but what I just posted is pretty much what I have been able to collect from my notes & from other builds. I'll do what I can this coming week. Phase 1 USDM stuff doesn't have much to be tossed around. We only have 3 types of EJ25Ds & 3 types of EJ22s as opposed to about 20+ other EJs that exist in other countries, so I don't know too much about them.


Id like some more info on the 25 heads on the 22t specifically, I've read that the whole obd1 to obd2 is going to need a standalone em, but what us the deal with the wiring harness? And what kind of gains are to be had?

It isn't hard to convert a 22T block to run on OBD2.
If you're putting 97-99 25D heads on the 22T, you must keep your wiring so this will mean keeping the 25D knock sensor (since knock sensors for DOHC & SOHC are different) & retaining the 25D wiring harness.
Cam & crank sensors are all the same & so are the crank gears.
All you have to do is swap over all of your 25D stuff to the 22T & it will run, without throwing a check engine light if you do everything correctly.
Keep the 22T water pump but get an 11mm oil pump to ensure that the heads & crank get oil at all times.
Also, get a piggyback ECU, more aggressive fuel injectors, & better fuel pump to compensate for the extra air pressure from the turbo.

[EJ22D]

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 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 size/thickness 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 head gasket with an EJ22 bore must be used & so on. You may also have to obtain special gaskets specifically designed to mate differing heads & blocks.

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.
The EJ22T head gaskets can be used to successfully mate DOHC EJ20/EJ25D heads to any EJ22 block.

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 away.
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.

All EJ22s have 52mm rod journals & all EJ25Ds have 48mm rod journals.
Hope this helps anyone who wants to have general info on EJ hybrids.
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.

*Revised*

[Outbackid]

For what it's worth, I successfully mated a JDM EJ25D block to USDM EJ251 Heads. You have to use EJ25D gaskets.

[harrymaneuvers]

Not a whole lot of info on Phase 2 EJ22 heads on EJ251 block which is what I am doing.


Any thoughts you could share on reliability, power, pro's, con's ect?

[EJ22D]

For what it's worth, I successfully mated a JDM EJ25D block to USDM EJ251 Heads. You have to use EJ25D gaskets.

The 251 crank gear is all that is required to make it work. You probably had to change the black coolant pipe & dipstick too.


Not a whole lot of info on Phase 2 EJ22 heads on EJ251 block which is what I am doing.


Any thoughts you could share on reliability, power, pro's, con's ect?

You're essentially creating a Phase 2 version of the Phase 1 high compression build but that would require the following:
222 heads with cam gears.
222 crank gear.
222 wiring harness.
251 or 222 manifold (use whichever one suits your needs).
251 camshafts (or you can swap & test cams from 222 to 251 to see which works best).
251 fuel injectors.
91+ octane at ALL times, no exceptions.

Phase 2 SOHC (EJ22s & EJ25s) are VERY close to being like one another.

[harrymaneuvers]

Interesting... why EJ251 injectors???

I was under the impression that everything above the shortblock needed to be whatever the ECU is.


For me, my car was originally an EJ222. So EVERYTHING is EJ222 except for the shortblock.

Why would I put EJ251 camshafts in the EJ222 heads?

[Outbackid]

For what it's worth, I successfully mated a JDM EJ25D block to USDM EJ251 Heads. You have to use EJ25D gaskets.

The 251 crank gear is all that is required to make it work. You probably had to change the black coolant pipe & dipstick too.


What do you mean by crank gear exactly?

[chuckthefuk]

Crank gear =

https://sl-i.net/FORUM/images/imported/2012/03/crank_sprocket_timing-1.jpg
https://sl-i.net/FORUM/images/imported/2013/03/B0u96EWkKGrHqJjIEw5CZoClDBMPJVptLg_35JPG-2.jpg

[Outbackid]

Crank gear =

https://sl-i.net/FORUM/images/imported/2012/03/crank_sprocket_timing-1.jpg
https://sl-i.net/FORUM/images/imported/2013/03/B0u96EWkKGrHqJjIEw5CZoClDBMPJVptLg_35JPG-1.jpg
Well that's bad. I did not swap mine over. How bad is that? I am definitley going to fix that like ASAP now, but how bad is it that I've put a couple thousand miles on it with the EJ25d one?

[EJ22D]

Interesting... why EJ251 injectors???

I was under the impression that everything above the shortblock needed to be whatever the ECU is.


For me, my car was originally an EJ222. So EVERYTHING is EJ222 except for the shortblock.

Why would I put EJ251 camshafts in the EJ222 heads?

1. I have heard that 251/3 injectors are better than the 222 injectors. This is just hearsay as I have not had the opportunity to actually see this in person. However, it won't hurt to keep them.

2. The ECU needs to be the one that is able to identify & run the cam gears & crank gear, both of which run the head & crank. For example, the 25D & 22E have the same exact crank & cam triggers, which is the cause of the 22E & 25D ECUs being able to run both the SOHC & DOHC cylinder heads of Phase 1.

3. The 251 camshaft has different lobes than the 222 cams & since you have both camshaft sets, now would be the perfect time to try them both out to see which set is actually the best for the high compression 22/25 build.


Well that's bad. I did not swap mine over. How bad is that? I am definitley going to fix that like ASAP now, but how bad is it that I've put a couple thousand miles on it with the EJ25d one?

Pause.
How is it that you are able to run a 25D block & retain it's crank gear with 251 heads on it?
From what I understand & what I have seen personally, the 251 & 25D have 2 totally different crank gears & cam/crank triggers.

[Outbackid]

Pause.
How is it that you are able to run a 25D block & retain it's crank gear with 251 heads on it?
From what I understand & what I have seen personally, the 251 & 25D have 2 totally different crank gears & cam/crank triggers.
I looked them over and they had the same amount of teeth. My car ran fine for about 3k miles, but now I'm running into a misfiring issue. I doubt that is related though, since I had a misfire issue just like this before I threw a rod. I stopped driving the car today just to be sure, so as soon as I get a chance I'll pull the timing cover and make sure that the two are the same.

[harrymaneuvers]

3. The 251 camshaft has different lobes than the 222 cams & since you have both camshaft sets, now would be the perfect time to try them both out to see which set is actually the best for the high compression 22/25 build.





Meh... a little too late for that as I already got torque grind Delta cams for the EJ222 heads.

[Outbackid]

My brother did some research and at least for the EJ22E and EJ25D, the crank gear is the same part #. He also said he counted teeth when when we were doing the timing on my hybrid motor and the one for the JDM EJ25D had the same amount of teeth as the EJ251 one.

[EJ22D]

My brother did some research and at least for the EJ22E and EJ25D, the crank gear is the same part #. He also said he counted teeth when when we were doing the timing on my hybrid motor and the one for the JDM EJ25D had the same amount of teeth as the EJ251 one.

What year is the 251?
This is very helpful info as it opens up possibilities for potential head swaps.

[Outbackid]

My brother did some research and at least for the EJ22E and EJ25D, the crank gear is the same part #. He also said he counted teeth when when we were doing the timing on my hybrid motor and the one for the JDM EJ25D had the same amount of teeth as the EJ251 one.

What year is the 251?
This is very helpful info as it opens up possibilities for potential head swaps.
2002 EJ251, unknown year JDM EJ25D and, if it matters, 1997 EJ22E.

[EJ22D]

My brother did some research and at least for the EJ22E and EJ25D, the crank gear is the same part #. He also said he counted teeth when when we were doing the timing on my hybrid motor and the one for the JDM EJ25D had the same amount of teeth as the EJ251 one.

What year is the 251?
This is very helpful info as it opens up possibilities for potential head swaps.
2002 EJ251, unknown year JDM EJ25D and, if it matters, 1997 EJ22E.

Your JDM 25D is most likely the 97-99 variation.
Also, are you absolutely sure that the reluctor teeth (where the timing mark is) are the same number as the 22E/25D reluctor teeth?

[1-3-2-4]

How driveable is a ej22e with ej25d heads without a turbo?

[EJ22D]

How driveable is a ej22e with ej25d heads without a turbo?

Depends on the compression ratio that you use.
8.5:1 will run a bit sluggish compared to SOHC variants but 9.5:1 will have a little more grunt than they do.

[1-3-2-4]

Well it would be a phase I

[EJ22D]

Well it would be a phase I

The power loss won't be intolerable but you'll wish you had that turbo on sooner than later.

[EJ22D]

Update.
Everyone, please keep in mind that when you swap heads, you must also use the dipstick tube & coolant pipes that came factory with those heads! For example, SOHC heads need to be swapped over with the SOHC oil dipstick due to the mounting points being different between SOHC & DOHC.

[legacy22]

Who all has done 1997 ej22e heads on the 1999 dohc ej25d? I am about to do this and have some questions. I know it can be done and boasts high compression. I'm just curious as to what all I take off what motors. I have 2 complete motors (ej25 has a seized cam and ej22 has a rod knock) What would you recommend purchasing and replacing when doing this swap. I am basically looking for a list of things to buy and what to take off each motors as I approach this swap. Maybe I'll even take notes and write up a diy for future reference.

Things I think should be in the list.
OEM 2.5 head gaskets.
OEM valve cover gaskets
OEM 2.2 timing belt.

Any seals I should replace? Idler pulleys? Water pump? Oil pump... etc. Any help is appreciated, links to threads etc.. thanks in advance.

['98Wagon]

Great thread! Thank you!

This answered a lot of questions I had about the 22t/25D hybrid I am working on putting together to take the place of my ej22 in my 98 wagon. Happy boosting here we come! :)

[EJ22D]

Who all has done 1997 ej22e heads on the 1999 dohc ej25d? I am about to do this and have some questions. I know it can be done and boasts high compression. I'm just curious as to what all I take off what motors. I have 2 complete motors (ej25 has a seized cam and ej22 has a rod knock) What would you recommend purchasing and replacing when doing this swap. I am basically looking for a list of things to buy and what to take off each motors as I approach this swap. Maybe I'll even take notes and write up a diy for future reference.

Things I think should be in the list.
OEM 2.5 head gaskets.
OEM valve cover gaskets
OEM 2.2 timing belt.

Any seals I should replace? Idler pulleys? Water pump? Oil pump... etc. Any help is appreciated, links to threads etc.. thanks in advance.

You must perform the following to create a high compression 2.5:

1. Use 22E heads, timing assembly, coolant pipe, & oil pipe.
2. After swapping those over, the engine is to be treated like a full 22E, so buy a full 22E rebuild kit w/seals.
3. Head gaskets are iffy. I would not use the stock 22E head gaskets on the 25D block.

[86bratman]

Head gaskets must match the bore of the block, and being an ej25d must be the thick variety to deal with the pistons coming slightly out of the block. That said most ppeople use OE subaru ej25d head gaskets on the "frankenmotor" plenty of info to be found for this on nasioc and ultimatesubaru.org

[EJ22D]

Head gaskets must match the bore of the block, and being an ej25d must be the thick variety to deal with the pistons coming slightly out of the block. That said most ppeople use OE subaru ej25d head gaskets on the "frankenmotor" plenty of info to be found for this on nasioc and ultimatesubaru.org

Head gaskets must also have the coolant port design of the heads that they are going to have pressed onto them.
In other words, you need to have a 22E gasket custom built with a 25D bore.
Using the OE 25D head gaskets on the 22E/25D hybrid creates a huge risk for head gasket failure.

[r3v_v3ng3]

Pause.
How is it that you are able to run a 25D block & retain it's crank gear with 251 heads on it?
From what I understand & what I have seen personally, the 251 & 25D have 2 totally different crank gears & cam/crank triggers.
I looked them over and they had the same amount of teeth. My car ran fine for about 3k miles, but now I'm running into a misfiring issue. I doubt that is related though, since I had a misfire issue just like this before I threw a rod. I stopped driving the car today just to be sure, so as soon as I get a chance I'll pull the timing cover and make sure that the two are the same.


From my experience, only the phase II 2.2/2.5 that is the california version (emission) that uses a different crank/cam gear. The way you can tell between the cali version and non cali is the IACV is 3 wire instead of the 6? wire, The map sensor is on the throttle body instead of the intake manifold and it doesn't use the air injection.

[EJ22D]

The thread has been lightly updated.

Also, if anyone has any other hybrid builds, here & now would be the perfect place so that the knowledge is preserved for future reference.

[Alucard]

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.

(I am EJ22D, but for some reason, I cannot access my original profile, so I made this one.)