Need specs on SOHC swap to Australian DOHC heads

[Nitemare1]

So recently acquired a 1991 SS car with the original SOHC heads on it. The car came with a pair of ej22t Australian heads that I would like to swap on the engine. I have read so many threads that I am cross eyed at this point. The gentleman that I bought the car from they would need to be machined for compression reasons. I thought less compression = more boost you can run???? Also im assuming all of the coolant passages should line up? coolant lines line up? I keep reading and reading and I see a lot of guys going back and forth and I cant just rely on hear say. Has anyone machined these and if so do you have any good specs that I can give to my machinist ?(thousandths/CC's) I have seen all of the threads with ej20 and ej25 swaps but not these Australian heads.... He said that these heads are extremely rare?????

[wtdash]

HI and Welcome,

Are you familiar w/the 22B model that Subaru made in about '98? It is the only Subaru model to have a 2.2 liter AND the DOHC heads that I've heard of....Yes, it's rare - like 400 ever made. ONLY 5 went to Australia!

According to the link above, 22B was based on the EJ20G engine in the WRX/STi of that time frame and was a closed-deck block. I believe the EJ22T in the USDM turbo cars is an original engine - not a bored out 2.0.

And if you read Japenese this LINK may have some info.

I'd measure the heads to verify their size.

If you truly have that set of heads, I'd probably sell 'em to buy an STi! - Probably not worth THAT much, but they are likely the most rare set of heads Subaru made for a production car, IMHO.

To answer your CR question, I don't know. Stock EJ22T is 8.0:1 CR; Stock EJ20G has been shown as "wrx were mainly 8:1, while sti 20Gs were mainly 8.5:1" from a NASIOC post.

Plus, you have to consider the head gasket thickness.

Yes, lower compression = more boost, from what I've read. Usually, the car is a slug off the line though.

I'd 'guess' that the EJ22T block and EJ22 DOHC heads are very similar in their passages, and many people have installed both the EJ20G and EJ25D DOHC heads on the stock EJ22T block, and just used the stock EJ22T head gasket (which worked fine on my build).

The smart people will add their input and NASIOC likely has more info....just watch out for the 'know-it-alls' over there.

IF you still have his contact, ask the PO where he got the heads and where the rest of the car is....Hard to believe they'd actually part one of those rare beasts out!

And please post some pics of the heads.

Td

[PhyrraM]

If your heads are Legacy EJ20G heads (2 bolts holding each coil) then your CR ends up pretty low, IIRC in the 7:1 range.

If your heads are WRX EJ20G or EJ20K heads (one bolt holding each coil) then your CR ends up a bit higher, maybe about 7.5:1.

Both are considered low for a street car, but folks opinions differ as to how it effects driving. I, personally, have never run these combos.


For the record...the 22B heads were basically EJ20K STI heads on a closed deck, phase 2, 2.2 block, with forged pistons to give the desired compression ratio.

[mike-tracy]

Click on the "sticky" at the top of the engine section, and look for the DOHC "unspoken details" thread. Contains lots of details about dohc swaps in general, and this one in particular.

Also, search for "thoughts on compression ratios," a member on here did the math to find all the ratios to the common hybrid builds.

[Nitemare1]

HI and Welcome,

Are you familiar w/the 22B model that Subaru made in about '98? It is the only Subaru model to have a 2.2 liter AND the DOHC heads that I've heard of....Yes, it's rare - like 400 ever made. ONLY 5 went to Australia!

According to the link above, 22B was based on the EJ20G engine in the WRX/STi of that time frame and was a closed-deck block. I believe the EJ22T in the USDM turbo cars is an original engine - not a bored out 2.0.

And if you read Japenese this LINK may have some info.

I'd measure the heads to verify their size.

If you truly have that set of heads, I'd probably sell 'em to buy an STi! - Probably not worth THAT much, but they are likely the most rare set of heads Subaru made for a production car, IMHO.

To answer your CR question, I don't know. Stock EJ22T is 8.0:1 CR; Stock EJ20G has been shown as "wrx were mainly 8:1, while sti 20Gs were mainly 8.5:1" from a NASIOC post.

Plus, you have to consider the head gasket thickness.

Yes, lower compression = more boost, from what I've read. Usually, the car is a slug off the line though.

I'd 'guess' that the EJ22T block and EJ22 DOHC heads are very similar in their passages, and many people have installed both the EJ20G and EJ25D DOHC heads on the stock EJ22T block, and just used the stock EJ22T head gasket (which worked fine on my build).

The smart people will add their input and NASIOC likely has more info....just watch out for the 'know-it-alls' over there.

IF you still have his contact, ask the PO where he got the heads and where the rest of the car is....Hard to believe they'd actually part one of those rare beasts out!

And please post some pics of the heads.

Td

Thanks for the info, Yeah he actually got them off of a guy in Australia of one of their legacy forums.... the car also came with a tone of other rare/hard to find parts.....

The car is actually listed in the Car lot thread under "the real deal 1991 SS"

I will take some pics of the heads asap.

[Nitemare1]

Click on the "sticky" at the top of the engine section, and look for the DOHC "unspoken details" thread. Contains lots of details about dohc swaps in general, and this one in particular.

Also, search for "thoughts on compression ratios," a member on here did the math to find all the ratios to the common hybrid builds.

Yeah I checked it out already.... a lot of info. Still trying to decipher a lot of it..... I didn't see the swap for the 2.2, just the 20 and 25, Ill look again....

[Nitemare1]

I guess I really need to talk to someone who has done this exact swap and see what #'s were as far as machine work and any issues that will need to be swapped/modified /address.....

[Nitemare1]

here are some pics of these heads...... For what its worth there are some "six star" head gaskets in the box with them and the valve covers have been re sealed. May be just leaking? may be has some wild cams?!?!?
I wouldn't be so luck lol

[Nitemare1]

http://s1367.photobucket.com/user/nitem ... sort=3&o=0

http://s1367.photobucket.com/user/nitem ... sort=3&o=1

http://s1367.photobucket.com/user/nitem ... sort=3&o=2

http://s1367.photobucket.com/user/nitem ... sort=3&o=3

[Nitemare1]

I wouldn't be so luck lol

You're kidding, right?

Idk Do they not have cam sets for these? im guessing no? lol Im a new school STi guy. I stumble upon this car locally and thought it would be cool to do a complete restoration.....

I have virtually no ej22 experience and I am reading and reading and reading trying to learn as much as I can so be patient with me!!!! lol

[PhyrraM]

Those are '89-'93 first gen Legacy EJ20G heads.

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[mike-tracy]

Rebuilt at some point

[Nitemare1]

Those are '89-'93 first gen Legacy EJ20G heads.

Sent from my MB860 using Tapatalk 2

Ok, so I guess that's good? lol I guess it should be a straight forward swap then? Well I guess he thought they were Australian..... So at this point I can just re read the head swap thread again.

[Legacy777]

I would tend to agree with PhyrraM. Those look just like standard EJ20G heads.

As previously mentioned, North America was the only country to get the EJ22t.

[mike-tracy]

Yeah the "audm" heads should be the same thing as "JDM" 2.0 turbo legacy heads.

[wtdash]

I wouldn't be so luck lol

You're kidding, right?

Idk Do they not have cam sets for these? im guessing no? lol Im a new school STi guy. I stumble upon this car locally and thought it would be cool to do a complete restoration.....

I have virtually no ej22 experience and I am reading and reading and reading trying to learn as much as I can so be patient with me!!!! lol

I'm just giving you grief because you might have had the rare EJ22B Heads AND you're stating it could have 'wild cams'. Just having the heads would've put in a league of your own - not to mention cams, too!

Delta cams can get you different grinds for the cams. The EJ20G cams are turbo specific (I don't know the specs), where as the EJ25D cams are NA-based, but seem to work fine on the EJ22T. Supposedly, both breathe @ least 20% better than the stock SOHC heads.

And you'll find this is the BEST Subie forum for info on the '89-94 Legacy- turbo and NA. Also, the ultimatesubaru.org/forum is good resource, if you need more late-night reading.



Also, I see on the heads what looks like a over-heat sensor, which means they were @ a wrecking/salvage yard sometime in their life>>EDIT - also means they may have been installed installed by an engine importer (more likely in this case).
Sensors are designed to 'pop' if engine is over-heated and void any warranty they would have had from the yard - over-heating is ALWAYS the owner's fault in that case.

Like mentioned above, they may be rebuilt...that's likely good news. You could have them pressure tested, checked for flatness and basically bolt them on.

BTW, you'll need to source a DOHC intake manifold (IM) from an EJ20G or (I think) an EJ25D. If you want to run the EJ22T stock pink side-feed injectors, you'll need the EJ20G rails for both IMs. The EJ22 from '89 -98 are considered Phase 1 (minor tweaks in '97 incl. engine became interference design, but still Phase 1), and the SOHC and DOHC IM's are not interchangeable. The '99+ Phase 2 IM's are NOT compatible w/the Phase 1 series. More details HERE.

Since you're used to STi power levels, you may want to check into the Rob tune, as well. But best to just get it running properly 'stock' before modding.....that way you have a good baseline to work from.


GL,
TD

[Legacy777]

Also, I see on the heads what looks like a over-heat sensor, which means they were @ a wrecking/salvage yard sometime in their life (sensors are designed to 'pop' if engine is over-heated and void any warranty they would have had from the yard - over-heating is ALWAYS the owner's fault in that case.)

Todd,

Where do you see an over-heat sensor in the heads? Which picture?

[wtdash]

Todd,

Where do you see an over-heat sensor in the heads? Which picture?

In the 3rd pic above - Circled here - or am I seeing things?:

[Nitemare1]

wtdash,

Im gonna pop out in the garage right quick and have a look at that. I noticed it but didn't take a close look.....

[Nitemare1]

ok, Deff some sort of quality control measure, it states "void if removed" obviously for warranty proposes

[PhyrraM]

That just means it was sold by an engine importer at one time. They put them on there to verify it wasn't overheated in case the customer makes a warranty claim.

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[wtdash]

That just means it was sold by an engine importer at one time. They put them on there to verify it wasn't overheated in case the customer makes a warranty claim.

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^This...way more likely than my scenario of a Yard, considering the US never had the EJ20G.

[cj91legss]

The gentleman that I bought the car from they would need to be machined for compression reasons. I thought less compression = more boost you can run????

Could he have possibly said that in case there might be a vent valve? That could be the compression issue the gentleman was speaking of.

[Nitemare1]

The gentleman that I bought the car from they would need to be machined for compression reasons. I thought less compression = more boost you can run????

Could he have possibly said that in case there might be a vent valve? That could be the compression issue the gentleman was speaking of.

I have no clue. he said from what he had read from this forum that swapping the ej20t DOHC heads to this ej22t engine would cause a drop in compression..... there fore I would need to have the heads machine to bump the compression back up to normal however he didn't know the CC's or how much to take off. I think he just bought them

Me, personally and just trying to find the machining specs required if any to have these heads prepped and ready...

[PhyrraM]

The compression will drop because the heads have larger chamber. If you machine the heads more than the Subaru recommended maximum, you will adversely effect the cam timing because the cam sprockets will now be closer to the crank pulley, but the timing belt is the same length.

The only proper way to raise compression is to use custom pistons. I would run it as is and decide for yourself if the compression is really too low.

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