DOHC vs SOHC.

[LegacyRebuild]

I have an EJ22E (I think that's what it is) in a 1997 Subaru Legacy L. Now I have been looking into the possibility into a DOHC conversion. I have heard that the SOHC doesn't flow as well as the DOHC but it has better low end response. However, I've heard that the DOHC has a smoother top-end/midrange response. I'm not looking for +T (Turbo) or anything like that yet. I just want to know what the pros/cons are for converting a EJ22 into DOHC. I know they have a DOHC EJ22 in Japan but that's a completely different motor (closed deck block).
What would I need other than DOHC heads & what would I be expecting if I were to have done the conversion?

[green97gt]

so the 2.2 SOHC had 137 hp NEW, and the 2.5 DOHC had 165 hp NEW thats a difference of 28 hp NEW

probably less if you swap heads and make the 2.2 DOHC...so you do the math, is the dollar / HP ratio worth it?

i personally am looking for a 2.2 SOHC just for the simplicity, or "bullet proofness"

[LegacyRebuild]

so the 2.2 SOHC had 137 hp NEW, and the 2.5 DOHC had 165 hp NEW thats a difference of 28 hp NEW

probably less if you swap heads and make the 2.2 DOHC...so you do the math, is the dollar / HP ratio worth it?

i personally am looking for a 2.2 SOHC just for the simplicity, or "bullet proofness"
I know that the ej22 is bulletproof in pretty much any form. I just want to know what I would need to complete the conversion & what to expect in terms of efficiency & response over a sohc ej22. I believe that despite the ej22e's shortcomings, it is often overlooked. Since I'm not making my legacy turbo, I'd like to properly tune what I have & the ej22 isn't a bad thing to work with.

[98redlgt]

plenty of people have swapped the ej22 heads onto their ej25 blocks to raise their compression so I don't see why you couldn't do the same. You would need to use the EJ22 headgasket and get a DOHC timingbelt. Everything else should bolt right up if I'm not mistaken. I'm pretty sure the intake manifold lines up fine! FYI, the reason people do the EJ22 head swap is due to the DOHC being horrible for blowing their HG's....keep that in mind! You should be able to find the EJ25 heads pretty cheap though and be sure to port them while their out!!!

[impreza_GC8]

I would think you would need a new ECU because your computer would not know what to do with an extra set of cams. I don't think its worth it. You will notice minimal, if any difference.

[LegacyRebuild]

plenty of people have swapped the ej22 heads onto their ej25 blocks to raise their compression so I don't see why you couldn't do the same. You would need to use the EJ22 headgasket and get a DOHC timingbelt. Everything else should bolt right up if I'm not mistaken. I'm pretty sure the intake manifold lines up fine! FYI, the reason people do the EJ22 head swap is due to the DOHC being horrible for blowing their HG's....keep that in mind! You should be able to find the EJ25 heads pretty cheap though and be sure to port them while their out!!!
Is there a way to stop the dohc headgasket drama? What kind flaws do the dohc heads have that cause them to destroy the headgaskets like that? Are there dohc heads that don't have this weakness? I'm really not into getting a 2.5 block since I already have a 2.2.

[Huffer]

It's the gasket. Not the head.

The original HG's had flaws in the design. The revised version is much better, and recommended to switch to if you have not already. Any enging that fails because of a HG leak typically doesn't do too well even after repair because the heads get damaged by the excessive overheating.

[chuckthefuk]

I would think you would need a new ECU because your computer would not know what to do with an extra set of cams. I don't think its worth it. You will notice minimal, if any difference.

BINGO! 100% you need a DOHC ecu (matching year as the heads) and all sensors including cam position sensor from the EJ25D to fire it up with no issues. However I am not 100% sure about the manifold, since EJ22E use MAP sensors and EJ25D use MAF sensors.

These Frankenstein builds are the "easiest" bolt-ons with the least amount of hassle. No messing with emission controls/evap system when swapping full motors from different years.

EJ25D
Pros: Louder more aggressive motor. Always dual-port exhaust. High end pulls well

Cons: Timing belts are a hassle. Head gasket is its Achilles heal. Low end does not pull well.

EJ22E
Pros: Quiet motor, single sometimes dual port exhaust, low end pulls well, almost bullet proof (with every seal gone this motor still fires up with no hesitation)

Cons: Under powered, top end does not pull well, no exhaust system can make this motor sound "rumbly" compared to 2.5 motors (some will argue)

-Chuck (my head hurts... ej this and ej that..)

[jey]

Actually I am pretty sure you will need the intake manifold that goes with the heads - the EJ22 manifold will not line up with the EJ25.

[LegacyRebuild]

I would think you would need a new ECU because your computer would not know what to do with an extra set of cams. I don't think its worth it. You will notice minimal, if any difference.
I have an ECU from a '98 Subaru Legacy Outback, if that helps. Also, Huffer was saying that the early HGs were poorly designed so if I stick with updated EJ22 HGs, I should be in the clear. I just want to know what would be the benefit of having DOHC on an EJ22E. I know that it will make some power (at least more than what it's kicking out in SOHC form). DOHC should make the power delivery more smooth & give the EJ22E a higher rev capacity though I'm just making hypothetical guesses. It's just that I believe the EJ22E deserves more attention than what it has been getting for a motor pretty much the entire population of Earth says is bulletproof. Even if it isn't a turbo, it's still a good motor. I'm just digging into this motor as much as I can before I can justify whether or not I should do a DOHC conversion.

[LegacyRebuild]

Here is what I have gathered from yesterday. DOHC - less reciprocating mass and more rotating mass = smoother response & more midrange/topend response (EJ25). SOHC - less rotating mass & more reciprocating mass = more low end response/some midrange response & poor top end response (EJ22). I think that sums it up personally because the SOHC explanation perfectly describes my current EJ22E motor. I won't really know until I do the conversion but I can safely predict that the EJ22E will retain some of it's low end response (being an H4 & all) while at the same time, delivering similar power to the DOHC EJ25 in terms of midrange response & top end. I've heard that I can use the stock ECU so long as it can read 16 valves & that using the EJ25 ECU might make the fused motor run too rich. Please feel free to correct me if I'm wrong. Also, if I were to use to the older EJ25D DOHC heads, I was also told that I would drop the compression from 9:7.1 to 9:5.1, making this new hybrid a non-interference type motor. Once again, feel free to correct me. I'm just trying to shed some light on this subject.

[rougeben83]

honestly, with all this trouble, I would just get a complete ej25 and drop it in there instead of trying to what is essentially is an excercise in futility. You'd be doing the same, if not less work since you don't have to open up the ej25 like you are planning to with that ej22.

[Reason]

Whoa whoa, there is so much wrong info in this thread, and I only read the first few posts. I'm on my phone and it will be a bitch to go back and forth to correct these.

But here's 2 things...

1. The ej22e doesn't use map sensors, I have a 22e and its MAF
2. The ej22 intake manifold won't line up with the ej25. €he ports are slightly different, the gaskets are not even close to being the same, and the bolts holes MIGHT be different.

[Reason]

I would think you would need a new ECU because your computer would not know what to do with an extra set of cams. I don't think its worth it. You will notice minimal, if any difference.

BINGO! 100% you need a DOHC ecu (matching year as the heads) and all sensors including cam position sensor from the EJ25D to fire it up with no issues. However I am not 100% sure about the manifold, since EJ22E use MAP sensors and EJ25D use MAF sensors.

These Frankenstein builds are the "easiest" bolt-ons with the least amount of hassle. No messing with emission controls/evap system when swapping full motors from different years.

EJ25D
Pros: Louder more aggressive motor. Always dual-port exhaust. High end pulls well

Cons: Timing belts are a hassle. Head gasket is its Achilles heal. Low end does not pull well.

EJ22E
Pros: Quiet motor, single sometimes dual port exhaust, low end pulls well, almost bullet proof (with every seal gone this motor still fires up with no hesitation)

Cons: Under powered, top end does not pull well, no exhaust system can make this motor sound "rumbly" compared to 2.5 motors (some will argue)

-Chuck (my head hurts... ej this and ej that..)

Chuck its the phase 2 ej25 SOHC that is MAP sensor based. And as for you theroy of 2.2ls not having a boxer rumble and no exhaust can help it, you never heard mine then have you? ;-)

[LegacyRebuild]

Well, I'm trying to learn as much as I can, so if anyone has anything to say, please feel free. I have an EJ22E & cannot get an EJ25 @ this time, so I have no choice but to stick with what I have. Also, for a motor as 'bulletproof' as an EJ22E, then it deserves attention. I have heard very much about the HG leaks & overheating from the late EJ25 N/As. I haven't really heard too much about the early EJ25 N/As.

[Reason]

I don't know why people think the 22e's are "bulletproof" - see plenty of subarus with blown 2.2's on craigslist. They may be more durable the the 25, but this bulletproof term is getting thrown around too much. The the 22T is different from the 22E, there's already a thread here that we already established.

[chuckthefuk]

Chuck its the phase 2 ej25 SOHC that is MAP sensor based. And as for you theroy of 2.2ls not having a boxer rumble and no exhaust can help it, you never heard mine then have you? ;-)

My EJ22 outback has a 2.25" exhaust w/ single port UEL headers. Its more inline-4 then flat-4 rumble. Also my friend with a EJ22 Brighton a de-catted forester exhaust.. result .... whisper quiet. Then he swapped a Ej25D with stock exhaust and my god what a difference.



I don't know why people think the 22e's are "bulletproof" - see plenty of subarus with blown 2.2's on craigslist. They may be more durable the the 25, but this bulletproof term is getting thrown around too much. The the 22T is different from the 22E, there's already a thread here that we already established.

Just add oil and drive. Some people forget the first part of that.. :-/
-Chuck

[JoshP]

A 2.5 DOHC is a simple swap to phase 1 2.2 cars. You dont even have to change engine harness over. Only thing is 2 port exhaust vs 1 port on the 2.2, so you will need a 2 port manifold.

[Reason]

Yea my exhaust is a little different, my secret weapon helps out my rumble too, anyone that heard it in person can tell you.

As for a swap a 2.5 into a 2.2 I have been thinking about the past few months is since the 2.2 dont have the EGR I was thinking about swapping in a JDM 2.5. It has no EGR and what not, I doubt I would need the ECU since they both dont have the EGR.

[JoshP]

if you 2.2 doesnt have EGR, then you can block the stuff off on the 2.5. The ecu isnt looking for EGR anyway.

[Legacy89]

Is my EDM 01 BE 2.5 DOHC? How do i check that?

I'm guessing that the BC is a SOHC.

[danci1973]

Is my EDM 01 BE 2.5 DOHC? How do i check that?

I'm guessing that the BC is a SOHC.
BE/BH models have EJ251 SOHC engine. At least over here in Europe.

Spot the difference:

SOHC:

https://sl-i.net/FORUM/images/imported/2009/10/SOHCEJ25-1.jpg

DOHC:

https://sl-i.net/FORUM/images/imported/2009/10/DOHCEJ25-1.jpg

D.

[chuckthefuk]

Is my EDM 01 BE 2.5 DOHC? How do i check that?

I'm guessing that the BC is a SOHC.

Check your strut tower.
http://img194.imageshack.us/img194/1913/vinplate.jpg

-Chuck

[ouch1011]

SOHC vs DOHC doesn't necessarily mean more flow/top end power. Especially since the SOHC EJ engines are still 16V just like the DOHC. That is more due to the port design and cam profile. Aside from the exhaust port design (single port is worse for performance), the intake ports should be almost the same. But, since the DOHC engine was supposed to be a kind of "performance" (not really) engine, I suspect they added a bit more valve lift and duration to move the powerband a bit higher in the RPM range, so more horsepower at the cost of some low end torque.

[parkcityboyx]

i was in this same state of mind with my ej22e and i couldnt make up my mind.

heres my info if it will help you out at all...

viewtopic.php?f=5&t=14637 (https://sl-i.net/FORUM/viewtopic.php?f=5&t=14637)

viewtopic.php?f=6&t=15582 (https://sl-i.net/FORUM/viewtopic.php?f=6&t=15582)

i was going to swap a JDM 2.5 for my 2.2 but i was a little sketch on wether or not i would have to rebuild it anytime soon. i guess it depends on who you buy it from and how confident you are in it. i had alot of people tell me that its kind of crazy to buy a used engine you dont know much about and just put it straight into your car. so i ended up just sticking with my ej22e and spicing it up quite a bit. shes pretty much a brand new engine now, head work, cam work, exhaust and other little stuff, and im pretty confident its going to be a FUN car.

all up to you and your budget.

[Reason]

People have been swapping used engines in there cars for well, as any of us have been alive. I'm pretty sure they will be doing it soon after we are all gone as well. If swapping unknown JDM engines that we dont know the history of was so bad, I doubt that there would be much profit in it. Last time I checked these companies are a dime a dozen.

I would make it a point to rebuild almost and used engine that you get your hands on before it goes in your car. Even if a shady salesman or Joe blow off the streets says the oil has been changed every 2000 miles and he never had any issues with it.

[parkcityboyx]

People have been swapping used engines in there cars for well, as any of us have been alive. I'm pretty sure they will be doing it soon after we are all gone as well. If swapping unknown JDM engines that we dont know the history of was so bad, I doubt that there would be much profit in it. Last time I checked these companies are a dime a dozen.

I would make it a point to rebuild almost and used engine that you get your hands on before it goes in your car. Even if a shady salesman or Joe blow off the streets says the oil has been changed every 2000 miles and he never had any issues with it.


AMEN :grin:

[parkcityboyx]

i wish i would have had the full budget to buy a JDM 2.5 and rebuild it, but i didnt.

[Yamazaki]

The J-spec EJ25D was only rated at 160ps(157.8hp), but the US-spec EJ25D was rated at 165hp. Why is this?
Now, the J-spec EJ254 was rated at 167ps(164.7hp), but I don't know if the US ever had an EJ254.....

Since those are the only two DOHC 2.5L NA engines that came out over here (until the BM/BR), why not just get a US-spec EJ25D?

[evolegacy]

The J-spec EJ25D was only rated at 160ps(157.8hp), but the US-spec EJ25D was rated at 165hp. Why is this?
Now, the J-spec EJ254 was rated at 167ps(164.7hp), but I don't know if the US ever had an EJ254.....

Since those are the only two DOHC 2.5L NA engines that came out over here (until the BM/BR), why not just get a US-spec EJ25D?

thats odd, cuz i feel like my J-spec EJ25D has more spunk to it than my USDM EJ25D (might have been the blown piston :smt005 )

[Yamazaki]

thats odd, cuz i feel like my J-spec EJ25D has more spunk to it than my USDM EJ25D (might have been the blown piston :smt005 )
That is odd, considering that if you're not using 93 Octane, you're using a lower grade of gas intended for the engine. And somebody please correct me if I'm wrong, but doesn't that take away a little from the power output?
It's only conjecture on my part, but I would suspect that any "power gains" from using non-EJ206/8 engines is psychological since they only make very modest power and require 93 Octane to do so. But again, that's conjecture on my part. I have no way of proving it other than reading the engine data in my books.

[evolegacy]

That is odd, considering that if you're not using 93 Octane, you're using a lower grade of gas intended for the engine.

im using 89 octane currently, are you saying that the J-Spec model has a compression ratio that requires the use of 93?

[Huffer]

Keep in mind, the US uses a different octane scale to rate the gasoline vs. Japan vs. New Zealand vs. Australia.

87 octane in USA = 91 octane in New Zealand

[Yamazaki]

That is odd, considering that if you're not using 93 Octane, you're using a lower grade of gas intended for the engine.

im using 89 octane currently, are you saying that the J-Spec model has a compression ratio that requires the use of 93?
I don't know the answer to that. My book says the compression for the J-spec EJ25D is 9.5, and for the EJ254 it's 10.7. I don't know what it is for the US-spec engines. However, it also says unleaded premium gasoline is the fuel for both the EJ25D and the EJ254, and there are only two grades of gas here - regular (US 93 Octane equiv) and premium (US 95.5-ish Octane equiv). However, almost all of the Americans here use regular because it's much cheaper for them (it's the only one offered on the military base), and there must not be anything really bad by putting in a lower grade because nobody cares enough to put in what the owner's manual calls for. Well, that and it's around $3.00 cheaper per gallon to just get regular on the base than premium in the city :cry:.

So there you go - a lot of information but no answer.

[danci1973]

I don't know the answer to that. My book says the compression for the J-spec EJ25D is 9.5, and for the EJ254 it's 10.7. I don't know what it is for the US-spec engines. However, it also says unleaded premium gasoline is the fuel for both the EJ25D and the EJ254, and there are only two grades of gas here - regular (US 93 Octane equiv) and premium (US 95.5-ish Octane equiv). However, almost all of the Americans here use regular because it's much cheaper for them (it's the only one offered on the military base), and there must not be anything really bad by putting in a lower grade because nobody cares enough to put in what the owner's manual calls for. Well, that and it's around $3.00 cheaper per gallon to just get regular on the base than premium in the city :cry:.

So there you go - a lot of information but no answer.
The service manual for my 1998-2003 Subaru Legacy / Liberty (BE/BH) says:

compression ratio: 10.0:1 (2.0 and 2.5 non-turbo), 9.0:1 (2.0 turbo)[/*:m:rkdyu36b]
fuel: non-turbo models 95 RON or more (except Australia- 90 RON or more), turbo model 98 RON or more[/*:m:rkdyu36b]

Now 95 RON would be 91-92 AKI / PON (supposedly this is most commonly used rating in the US) or 85-87 MON.

It's not just compression ratio that defines what octane fuel the engine needs. I have a motorcycle with a compression ratio of 12.3:1 and the book says to run on 95 RON fuel - and it runs fine.

To answer the question you asked earlier - higher octane doesn't mean higher 'quality' (or 'grade'). Generally, lower octane fuels burn faster, thus they produce more power and less emissions - the difference is small, but figure in the lower price and it makes sense to use to lowest octane rating fuel that still won't make your engine knock...

D.

[LegacyRebuild]

EJ25D
Pros: Louder more aggressive motor. Always dual-port exhaust. High end pulls well

EJ22E:
Cons: "no exhaust system can make this motor sound "rumbly" compared to 2.5 motors (some will argue)"

-Chuck (my head hurts... ej this and ej that..)
You are right. My EJ22E sounds almost nothing like an EJ25D (or any EJ25 for that matter). I have an aftermarket exhaust on my car now & it doesn't sound anything like an EJ25 though you can definitely tell it's a Subaru.

Stock:
http://www.youtube.com/watch?v=i4QpnT-dPJc

Aftermarket: (FC Content)
http://www.youtube.com/watch?v=rtfsOD4VB9A

[Reason]

EJ25D
Pros: Louder more aggressive motor. Always dual-port exhaust. High end pulls well

EJ22E:
Cons: "no exhaust system can make this motor sound "rumbly" compared to 2.5 motors (some will argue)"

-Chuck (my head hurts... ej this and ej that..)
You are right. My EJ22E sounds almost nothing like an EJ25D (or any EJ25 for that matter). I have an aftermarket exhaust on my car now & it doesn't sound anything like an EJ25 though you can definitely tell it's a Subaru.

Stock:
http://www.youtube.com/watch?v=i4QpnT-dPJc

Aftermarket: (FC Content)
http://www.youtube.com/watch?v=rtfsOD4VB9A


The first problem is you have the silencer on, second what is your full set up? Stock header and cats?

[LegacyRebuild]

EJ25D
Pros: Louder more aggressive motor. Always dual-port exhaust. High end pulls well

EJ22E:
Cons: "no exhaust system can make this motor sound "rumbly" compared to 2.5 motors (some will argue)"

-Chuck (my head hurts... ej this and ej that..)
You are right. My EJ22E sounds almost nothing like an EJ25D (or any EJ25 for that matter). I have an aftermarket exhaust on my car now & it doesn't sound anything like an EJ25 though you can definitely tell it's a Subaru.

Stock:
http://www.youtube.com/watch?v=i4QpnT-dPJc

Aftermarket: (FC Content)
http://www.youtube.com/watch?v=rtfsOD4VB9A


The first problem is you have the silencer on, second what is your full set up? Stock header and cats?

1)I'm going to take off the silencer & see if it's needed or not.
2)I am indeed running with stock header & cats. (I keep the cats on because i absolutely hate CELs).

[Reason]

Here is my 2.2 (small exhaust leak at the header/cyl head)

https://sl-i.net/FORUM/images/imported/2009/10/th_MOV00374-1.jpg (http://s2.photobucket.com/albums/y16/EJ25Legacy/VIDEOS/?action=view&current=MOV00374.flv)

[LegacyRebuild]

Here is my 2.2 (small exhaust leak at the header/cyl head)
Your car sounds vicious. You're more closer to the EJ25 warble than me.
Here is mine w/the silencer removed:
http://www.youtube.com/watch?v=g37mVkMEArs

Also, here is a comparison between the stock & aftermarket muffler that I have:
http://i578.photobucket.com/albums/ss226/850DegreesF/Picture300.jpg

[Reason]

That is with stock cats too and a borla single port header.

[LegacyRebuild]

That is with stock cats too and a borla single port header.
Borla single port header? Are they the only company that makes those? I have single port exhaust also & I've been looking for a good header for the longest.

[Reason]

That is with stock cats too and a borla single port header.
Borla single port header? Are they the only company that makes those? I have single port exhaust also & I've been looking for a good header for the longest.


They aren't in production anymore, it would be near impossible to find one. The was a guy on RS25.com that had single port headers made and selling them.

[evolegacy]

if you need to compare sound quality between a 2.2 and a 2.5, you can use reason for a 2.2 and this one here of mine for a 2.5, I'll upload another video that i have just waiting for photobucket to transfer it. not the best video since it was done quick but i got up to 5k, never redlined.

setup is OBX Race headers, OBX hi-flo Cat, custom 2.25" plumbing w/universal N1 Exhaust

::Edit::
yes it backfired a couple times and no its not resonated, although it needs to be

http://s25.photobucket.com/albums/c73/evotrance/?action=view&current=video004.flv

[LegacyRebuild]

if you need to compare sound quality between a 2.2 and a 2.5, you can use reason for a 2.2 and this one here of mine for a 2.5, I'll upload another video that i have just waiting for photobucket to transfer it. not the best video since it was done quick but i got up to 5k, never redlined.

setup is OBX Race headers, OBX hi-flo Cat, custom 2.25" plumbing w/universal N1 Exhaust

::Edit::
yes it backfired a couple times and no its not resonated, although it needs to be

http://s25.photobucket.com/albums/c73/evotrance/?action=view&current=video004.flv
Our idles sound different but our revs sound almost exactly alike.

[LegacyRebuild]

That is with stock cats too and a borla single port header.
Borla single port header? Are they the only company that makes those? I have single port exhaust also & I've been looking for a good header for the longest.


They aren't in production anymore, it would be near impossible to find one. The was a guy on RS25.com that had single port headers made and selling them.
Is that guy still there or no?

[Grafton]

check out the headers i had made for me for $70 in my members rides thread

headers : viewtopic.php?p=173762#p173762 (https://sl-i.net/FORUM/viewtopic.php?p=173762#p173762)

sound clip
http://www.youtube.com/watch?v=zT_fHE5f-zA,

btw the place i had these built @ is in fairmont wv

[Reason]

check out the headers i had made for me for $70 in my members rides thread

headers : https://sl-i.net/FORUM/viewtopic.php?p=173762#p173762

sound clip
http://www.youtube.com/watch?v=zT_fHE5f-zA,

btw the place i had these built @ is in fairmont wv


It sounds like a loud stock exhaust, is it just the header that has been changed?

[Grafton]

headers, high-flow cat, and a gutted 02 wrx muffler.

a different muffler would make it sound worlds better, but i am happy where it is for now until i get some other things done

[Bohemian_Funk]

Chuck its the phase 2 ej25 SOHC that is MAP sensor based. And as for you theory (fixed spelling) of 2.2ls not having a boxer rumble and no exhaust can help it, you never heard mine then have you? ;-)

All right wait, something about this isn't quite right methinks. Granted, maybe the phase II EJ25 in my '99 2.5RS has a slightly different setup, but I was just doing some research on the air sensors on the phase II SOHC EJ25 (in fact, that's why I came upon this thread), and according to the NASIOC "98-01 RS differences" sticky thread (found in the N/A powertrain subsection's FAQ/Threads of Note), the phase II design actually uses a MAF sensor. However, you may be able to take that with a grain of salt, as further research suggests that a MAF-based setup also has a MAP sensor, likely for backup in case the MAF sensor fails (read: common problem, especially with CAI/SRI setups due to lack of Hemholtz resonator aka snorkus, among other parts). Realize of course that this is all based on information found on the internet, and as such may not necessarily be trustworthy.

Other than that, so long as your EJ22 has an unequal length header, you will have the so-called "boxer rumble". An equal length header will still make a bit of a rumble (S**t, it's still a Subaru after all), it just isn't as prominent. If you're REALLY worried about having that boxer rumble, you have two options (assuming you don't all ready have a UEL header): get an OE (Original Equipment, not Old English) N/A Subaru UEL header, or weld up your own damned header (I can come up with a good source of steel tubing if you PM me; my best friend is a welder by trade, and as such has a company he can go through for metal. Anyone can use this company, btw). Either way, unless you have an aftermarket exhaust, you're not going to get that boxer rumble anyway :smt023.

My 2 cents,
~ Scott :smt028

[Edit: Sorry Huffer, I was in the middle of an Engineering Graphics class when I posted this. Won't/shouldn't happen again. :smt023.]

[danci1973]

All right wait, something about this isn't quite right methinks. Granted, maybe the phase II EJ25 in my '99 2.5RS has a slightly different setup, but I was just doing some research on the air sensors on the phase II SOHC EJ25 (in fact, that's why I came upon this thread), and according to the NASIOC "98-01 RS differences" sticky thread (found in the N/A powertrain subsection's FAQ/Threads of Note), the phase II design actually uses a MAF sensor. However, you may be able to take that with a grain of salt, as further research suggests that a MAF-based setup also has a MAP sensor, likely for backup in case the MAF sensor fails (read: common problem, especially with CAI/SRI setups due to lack of Hemholtz resonator aka snorkus, among other parts). Realize of course that this is all based on information found on the internet, and as such may not necessarily be trustworthy.
According to the 1999-2003 Liberty/Legacy Service Manual there is no MAF in EJ251 (phase II SOHC 2.5) engine. Just MAP.

This model also gets a 2.0 TURBO engine - that one has a MAF. But no 'bAckup' MAP.

D.

[Bohemian_Funk]

Hmm... Strange. I shall have to take a nice, close look at my intake system when I take delivery of said 2.5RS this Saturday. I shall dearly hope that I'm wrong, and that it indeed has a MAP setup, as that car desperately needs an intake (the previous owner had a custom exhaust made, but the intake is entirely stock), and I just want a nice, simple fender CAI.

Also, ah shoot I accidentally erased most of that post, and accidentally typed your username instead of Reason's. I'll edit that right after I submit this post.

~ Scott :smt028

[Huffer]

Ok, here's some clearing up for you:

Impreza RS 98-99 = MAF = 2.5L DOHC
Impreza RS 99-01 = MAP = 2.5L SOHC

Legacy 95-99 = MAF = DOHC if 2.5L
*some* Legacy 99 usually 30th ann = MAP
Legacy 00-04 = MAP = SOHC

[MDLP412]

i have a 1997 2.5 DOHC in my dads garage apart for headgaskets if you would be interested in maybe swapping heads and nessacary parts. where you located? PM me if your interested.

[danci1973]

Legacy 00-04 = MAP = SOHC
Don't know about other Subarus, but Legacy BE/BH are 1999-2003 in Europe and probably Australia...

D.

[Bohemian_Funk]

Ok, here's some clearing up for you:

Impreza RS 98-99 = MAF = 2.5L DOHC
Impreza RS 99-01 = MAP = 2.5L SOHC

Legacy 95-99 = MAF = DOHC if 2.5L
*some* Legacy 99 usually 30th ann = MAP
Legacy 00-04 = MAP = SOHC

Huffer, how certain are you on this information? Everywhere I've looked has listed the 99 Impreza RS as being when they introduced the Phase II SOHC engine. Granted, maybe they were talking about the build date, and not the model year. On top of that, everywhere I've looked has also listed the newer models of Subarus having MAF sensors, while the older ones had MAP sensors. Regardless, there should really be a sticky in either NASIOC or here, or at least SOMEWHERE in which there is a list of Subaru engines by year/model listing information such as port configuration, cam configuration, bore x stroke, displacement in cc, air sensor type, and stock head information such as cfm. I'm tired of looking through pages and pages of arguments and "he says she says" bull crap just to find some information that could potentially not even be right. Lord knows wikipedia's the same way, too.

~ Scott :smt028

[evolegacy]

I can vouch for huffer's info on the 98 Legacies having the 2.5L w/MAF, i bought mine stock and it was equipped with this.

[Bohemian_Funk]

I can vouch for huffer's info on the 98 Legacies having the 2.5L w/MAF, i bought mine stock and it was equipped with this.

That's good, though seeing as how I've got a 99 Impreza RS that I've only gotten a fairly brief look at under the hood (as previously stated, I will be signing a check/receiving a title on Saturday, and as such do not actually own/have the car yet), I'm actually far more interested specifically in the 1999 model, which I thought I saw was an SOHC. However, I will admit that I was far more interested in how much oil it had than what cam configuration it was. My last car leaked like a sieve. Lost an engine to that issue, in fact. Stupid Jiffy Lube destroying the oil filter receiver threads, I'm never letting somebody else change my oil again :smt011. Regardless, I have no doubt that Huffer could very well be correct, it's not like he hasn't been in the past :smt023.

~ Scott

[4n70n1n0]

The Impreza's are confusing. They got the EJ25D for 98, 99 got a mix, and the 00 to 01 got the EJ253.

That's that info I have in my head.

Now for the OP dude, ur better off doing a HCF - High Compression Franken

Take both EJ25 and EJ22 and make one engine that is 10.8:1 compression by using the EJ22 heads on the EJ25 block, but that's just me :D I don't think there is ANY pro to swapping the EJ25D heads on the EJ22E motor. It lowers ur compression, but at that point u might as well take advantage of that and turbo the thing.

[Huffer]

Ok, here's some clearing up for you:

Impreza RS 98-99 = MAF = 2.5L DOHC
Impreza RS 99-01 = MAP = 2.5L SOHC

Legacy 95-99 = MAF = DOHC if 2.5L
*some* Legacy 99 usually 30th ann = MAP
Legacy 00-04 = MAP = SOHC

Huffer, how certain are you on this information? Everywhere I've looked has listed the 99 Impreza RS as being when they introduced the Phase II SOHC engine. Granted, maybe they were talking about the build date, and not the model year. On top of that, everywhere I've looked has also listed the newer models of Subarus having MAF sensors, while the older ones had MAP sensors. Regardless, there should really be a sticky in either NASIOC or here, or at least SOMEWHERE in which there is a list of Subaru engines by year/model listing information such as port configuration, cam configuration, bore x stroke, displacement in cc, air sensor type, and stock head information such as cfm. I'm tired of looking through pages and pages of arguments and "he says she says" bull crap just to find some information that could potentially not even be right. Lord knows wikipedia's the same way, too.

~ Scott :smt028

Here's the issue - it VARIES by model year, chassis year AND place of delivery.

JDM vehicles are typically the following: 94-98 = BD/BG, 99-03 = BE/BH
USDM vehicle are: 94 = BC/BJ, 95-99 = BD/BG, etc

I am 100% certain that my list is correct for USDM vehicles, providing the intake sensor is stock.

[Bohemian_Funk]

Yeah, I knew the year splits for Legacy chassis', I was just wondering about Impreza's (my Legacy got totaled last month or so, and I'm replacing it with a '99 Impreza RS), as there doesn't really seem to be any widely known, clear distinction as to what engine the RS models got on which year, or at least there isn't for the 99 model; this is quite possibly because of what 4n70n1n0 (who's name confuses me as to what it means, I'm guessing "Antonino") mentioned earlier about 99 getting a mix, which probably means that there's basically a USDM "MY99.5" model where they went for the SOHC phase II engine. Either way, I guess we'll see what I end up with, but I have a sneaking suspicion that you may quite possibly be right, in which case I'll be saving up for some cometic headgaskets and arp head studs :smt005.

Oh yeah, I'll have a members ride II thread up about as soon as I get the new car btw. I'd have had a members ride I thread up for the Legacy, but it wasn't in any shape to be taking pictures of it or anything like that by the time I found this place, i.e. - my friends had put about a million dents in it, the main one of which encompassed essentially the entire left corner of the front bumper. It was a stock white Legacy L wagon anyway, nothing really special about it other than being a Legacy (of which you see one almost every block or so here in the Pacific NW).

~ Scott :smt028

[Huffer]

ALL vehicle years are split. Ever wonder why they start selling the 2010 vehicles in September? That's because they rolled off production in August 2009.

So technically a 2010 model was manufactured mid-2009.

Don't get hung up on the year to year changes. This is a 3 page thread that really is way offtopic.

DOHC vs. SOHC? Easy. 4 cams instead of 2, heavier vs. lighter, more moving parts vs less.

[Bohemian_Funk]

Yeah I agree, sorry for getting us off-topic, though it was still along the lines of a DOHC vs. SOHC issue.

Also, +1 ^, it is a quite easy decision provided you know what you want. If you want a little bit more low end torque/smoothness (I only say smoothness out of educated guessing. I've not yet driven a DOHC Subaru that I know of, but the idea that an engine that doesn't have to turn double the amount of cams would probably be a bit smoother at particularly low engine speeds isn't really a hard one to wrap your head around) due to less rotational mass, but less power potential up top, go SOHC. If you're willing to give up a tiny bit of drivability at low rpm's, but better high rpm power/control (in a tuning sense, not a driving sense), go DOHC. Personally, I think it's a no-brainer for anyone who can drive a manual, and not even a question for somebody that knows how to/is willing to rev-match/heel and toe/do various other foot techniques whilst driving. Otherwise, ask the wife/girlfriend/effeminate life partner of your choice.

~ Scott

[Huffer]

I've had both, and I prefer the quieter, smoother running SOHC found in the RS. Problem is, I like the Legacy GT body. So unless I build a franken motor with the SOHC shortblock and the DOHC heads, I'm outta luck. :smt006

[4n70n1n0]

in before lock

SOHC has better torque and its easier to change spark plugs :grin: I hate changin spark plugs on the EJ25D :smt022

[Bohemian_Funk]

Meh, I must admit, I'm getting somewhat tired of running out of puff after 5000 rpm or so. Personally, I can't wait to be able to afford a set of EJ25D heads, an EJ20 crank, and a custom set of rods/0.5mm overbore pistons to do a nice 11.5:1 CR n/a build with Cosworth double valvesprings and oversized valves. Gonna be sweet. Sure, I'll lose a good 150cc of displacement or so, but it'll probably be worth it, methinks. :cool:. Heh, call it the "2.4RS" :lol:.

~ Scott :smt028

[4n70n1n0]

If you want power, why not just swap in a EJ20 from a USDM 02 WRX

Best bang for your buck, but if u are a N/A lower like I and are stuborn like me, then u won't listen to me and do it anyways

U want N/A DOHC power, 04 Sti block, EJ253 crank, high comp pistons, Port and Polished JDM EJ20 DOHC heads, custom cometic head gasket, Delta cams, LW pulleys, full exhaust, + a tune

I might be wrong somewhere there, but that's the cocktail I've had in mind for a while, but just don't have the funds for it :D

Good luck

Rog, sorry for goin OT.... again

[Reason]

If you want power, why not just swap in a EJ20 from a USDM 02 WRX

Best bang for your buck, but if u are a N/A lower like I and are stuborn like me, then u won't listen to me and do it anyways

U want N/A DOHC power, 04 Sti block, EJ253 crank, high comp pistons, Port and Polished JDM EJ20 DOHC heads, custom cometic head gasket, Delta cams, LW pulleys, full exhaust, + a tune

I might be wrong somewhere there, but that's the cocktail I've had in mind for a while, but just don't have the funds for it :D

Good luck

Rog, sorry for goin OT.... again

I swear Ant me and you think alike sometimes. I had plans to do a slightly different build but very close, same block atleast ;-) I have the whole build on paper since my GT days. Sigh...... I doubt the L will see this build either.

[Bohemian_Funk]

If you want power, why not just swap in a EJ20 from a USDM 02 WRX

Best bang for your buck, but if u are a N/A lower like I and are stuborn like me, then u won't listen to me and do it anyways

U want N/A DOHC power, 04 Sti block, EJ253 crank, high comp pistons, Port and Polished JDM EJ20 DOHC heads, custom cometic head gasket, Delta cams, LW pulleys, full exhaust, + a tune

I might be wrong somewhere there, but that's the cocktail I've had in mind for a while, but just don't have the funds for it :D

Good luck

Rog, sorry for goin OT.... again

Yeah, that's essentially the kind of setup that I was thinking about, with a few exceptions such as using a nitrided EJ207 crank, since you can get them brand new for fairly cheap. Certainly not as cheap as an EJ253 crank, but I think it'd probably be worth it depending on how fast you want the crank to spin (nitrided crank + 75mm stroke + new forging = better than used 79mm stroke crank for extended high rpm use). Also, as I mentioned earlier, Cosworth has a set of MLS headgaskets made specifically for high-compression applications (or, if you really wanted to do some trick s@#$, you could have matching "hill/valley" grooves machined into the head and block, and forego the gaskets all together. I can't remember who exactly uses such a technique, but I think it's either NASCAR or F1. Certainly a good way to stop headgaskets from blowing :smt005.). You may be able to find them for cheaper than a custom set from Cometic, simply because they're all ready in production.

And of course I'd go with Delta cams :twisted:. Why pay shipping when I can get a good set made AND pick them up myself? :grin: (For those somehow not in the know, Delta Cams is located in Tacoma, WA)
~ Scott

[Sarra]

If you're going to stay NA, and 'go all out' on a build, forget EJ. Go EG33, high compression pistons, do a little headwork, and voila, your transmission now needs to be replaced! Seriously, a totally stock 1995 SVX, heavy as hell (4,000 lbs), with the really shitty automatics Subaru put in them, is faster than a stock 2002-2003 WRX. High CR, make the heads flow better, and stick it in a Legacy, pair it up with a WRX gearbox, or even better, a regeared 6MT, and holy hell, it's NA, and very fast.

It also had a 7,000 RPM redline stock. If I could find a 1997 SVX engine, computer, and everything to make it a 'legal OBDII swap', I'd do it. Problem is, most of them are 1991-1995, and not OBDII.

As for EJ25D vs EJ251/EJ252... Well, I've owned an EJ25D, an EJ251, and an EJ252.

My EJ251 experience was jaded, seeing how that engine was paired up with a 3.9 final drive. It was slower, dumber, and less mod friendly than my EJ25D. The EJ25D with the 4.11 final drive was a blast to drive, and kept up with a lot of other vehicles, and embarrassed a few diesels and other 'fast' cars. The EJ252 is in a heavy assed Outback with a 4EAT, and that's about all I can say, other than it sounds like it might have a little rod knock with only 70k on the motor (my mom's car).

I modded both of the Legacies I had. The EJ25D got an intake and an exhaust manifold. God what a pain it was, that TWE EL manifold weighed like 35 lbs. It was worth it, though. It pulled very hard up top, and was easily able to match the low end of an SOHC Legacy. The only good thing about the SOHC was... I submerged the engine in water, water came up to the bottom of the windshield, and I didn't hydrolock the motor. Somehow.

If I were to build one... It would be an EJ25D. Better heads, funner cams. The only SOHC motor I'd even consider is the EJ253, but that would be too much work getting the AVCS working, and for nearly no 'real gain' over the DOHC phase 1 motor.

[4n70n1n0]

If you want power, why not just swap in a EJ20 from a USDM 02 WRX

Best bang for your buck, but if u are a N/A lower like I and are stuborn like me, then u won't listen to me and do it anyways

U want N/A DOHC power, 04 Sti block, EJ253 crank, high comp pistons, Port and Polished JDM EJ20 DOHC heads, custom cometic head gasket, Delta cams, LW pulleys, full exhaust, + a tune

I might be wrong somewhere there, but that's the cocktail I've had in mind for a while, but just don't have the funds for it :D

Good luck

Rog, sorry for goin OT.... again

I swear Ant me and you think alike sometimes. I had plans to do a slightly different build but very close, same block atleast ;-) I have the whole build on paper since my GT days. Sigh...... I doubt the L will see this build either.


With that said when are you going to give me that title I asked you for some time back eh?

Just take ur time, like I am. You dont need this motor built for tomorrow. Just do what you do best, stock pile parts :smt005 and once u have everything put it all together and YAM! you got it done :smt023

[Reason]

I don't remember what I ate for breakfast yesterday man lol